308-07A-1 DIAGNOSIS AND TESTING Electronic Shift Refer to Wiring Diagrams Cell 34, Four-Wheel Drive Systems for schematic and connector information. Special Tool(s) 308-07A-1 Vacuum Test Tool, Knuckle Seal 205-826 Special Tool(s) 73III Automotive Meter 105-R0057 or equivalent Vacuum Test Plug, ABS Sensor 205-796 Worldwide Diagnostic System (WDS) Vehicle Communication Module (VCM) with appropriate adapters, or equivalent diagnostic tool Vacuum Pump 014-R1054 or equivalent General Equipment Pressure Vacuum Module 105-R0099 or equivalent Material Item Premium Long-Life Grease XG-1-C or XG-1-K (Canada CXG-1-C) Specification ESA-M1C75-B Principles of Operation Electronic Shift on the Fly (ESOF) System The electronic shift on the fly (ESOF) system is an Test Tool, Vacuum Hub electronic shift system that allows the operator to 205-827 choose between 2 different 4x4 modes as well as 2-wheel drive. The operator can switch between 2H and 4H mode at speeds up to 88 km/h (55 mph). To engage or disengage 4L, the 4x4 generic electronic module (GEM) requires that the vehicle speed be less than 5 km/h (3 mph), the brake pedal Vacuum Test Stand, Hublock pressed and the transmission in NEUTRAL (or 205-829 clutch pedal applied on manual transmission vehicles). This system contains pulse vacuum hublocks (PVH). The selector on the hublock, when turned fully counterclockwise to the AUTO position, engages/disengages the hub depending on the driver-selected 4x4 mode of operation. The hublocks Vacuum Test Stand, Hub also contain a manual override. When the selector Bearing is rotated fully clockwise to the LOCK position, the 205-828 4x4 vacuum and electronic system used for coupling the front axle to the wheels is bypassed. Copyright 2003, Ford Motor Company Last updated: 3/5/2008
308-07A-2 The transfer case is equipped with a dual-cone synchronous clutch. This clutch is used to synchronize the front driveline to the rear. All other internals operate in the same manner as the manual shift system. When the mode select switch (MSS) on the instrument panel is turned, the 4x4 module powers the transfer case shift motor, which activates a shift fork and engages the clutch. When the shift motor reaches the desired position, as determined by the encoder position inputs to the 4x4 module, power to the shift motor is removed. When the transfer case front and rear output shafts are synchronized, the lockup collar mechanically engages the mainshaft hub to the drive sprocket. At this point, the front axle PVHs are engaged. Instrument cluster 4x4 and Low Range indicator operation is controlled via hardwired outputs from the 4x4 module. Electronic Shift Transfer Case The New Venture Gear NV 273 electronic shift transfer case is a 3-piece aluminium design. The unit transfers engine power from the transmission to the front and rear axles. Under normal driving conditions the unit is in 2-wheel drive high (2H), but when desired, the operator may shift into 4-wheel drive high (4H) or 4-wheel drive low (4L). The transfer case is shifted electronically. The unit is lubricated by a positive displacement fluid pump that channels fluid flow through holes in the mainshaft. The encoder assembly used for mode indication is of a Hall-effect type. The system uses a total of 4 independent transistors for mode recognition. Each transistor is associated with a specific range of motor movement. When the circuit to each transistor is closed, a ground path to any of the A, B, C or D encoder pins is accomplished. When the circuit to each transistor is open, the connection to any of the A, B, C or D encoder pins is pulled to voltage. Mode indication is decoded by the 4x4 module based on the varying combinations of signals coming from the transistors. Pulse Vacuum Hublocks The electronic shift-on-the-fly (ESOF) system has a feature which allows the driver to override the vacuum-operated hublocks. When the front hublock dials are manually turned to the LOCK position, the hublocks are locked through the dial at all times, regardless of the position of the instrument panel mode select switch (MSS). 308-07A-2 When the front hublock dials are manually turned to the AUTO position, the hublocks use an internal spring-locking mechanism that is vacuum-operated by the ESOF system, and are locked with the MSS in the 4H or 4L position and unlocked with the MSS in 2H position. Refer to Hublock in this section for additional AUTO hublock system operation. Hublock Operation With the hublocks in the AUTO position, the 4x4 ESOF system uses timed vacuum sequences to lock and unlock the wheel ends when switching the instrument panel MSS between 2WD and 4x4 modes. A high vacuum level (222 mm [8.75 in] Hg and greater) is applied to the hublocks to lock the internal spring mechanism that engages (locks) the hublocks for 4x4 mode, and a lower vacuum level (114 to 184 mm [5.9 to 7.1 in] Hg) is applied to unlock the spring mechanism that disengages (unlocks) the hublocks for 2WD mode. The vacuum signals are supplied to the hublocks by system components, including the 4WD control module or GEM, wiring harness, solenoid, vacuum harness and vacuum seals. As a first step in service, eliminate obvious items such as loose wiring connections, loose vacuum connections or damaged vacuum lines. Hublock Engagement/Disengagement Time With the hublock dials in the AUTO position, switching the instrument panel MSS to 4x4 HIGH or 4x4 LOW results in the high vacuum level being applied to the hublocks, which lasts for at least 51 seconds (including a venting cycle). The hublocks should engage during this time through the spring mechanism. Switching the MSS to 4x2 less than 51 seconds after the MSS has been switched to 4x4 HIGH or 4x4 LOW will not interrupt the high vacuum level; instead, the lower vacuum level will be applied after the high vacuum level cycle is completed.
308-07A-3 With the hublock dials in the AUTO position, switching the MSS to 2WD results in the lower vacuum level being applied to the hublocks, which lasts for about 15 seconds. However, the actual time required for the hublocks to disengage by spring force can vary considerably due to the effects of driveline wind-up. Road bumps, vehicle speed, acceleration cycles or momentary reversal of direction can assist this process. Switching the MSS to 4x4 HIGH or 4x4 LOW always overrides the lower vacuum level cycle and results in an immediate high vacuum level and in locking of the hublocks. Electronic Shift On-the-Fly (ESOF) Automatic Hublock Operation Manual Override 308-07A-3 The AUTO hublocks have a manual override selector dial, which, when turned to the LOCK position, will keep the hublocks locked (through the dial) at all times, regardless of the position of the instrument panel MSS. (Always set both hublock dials to the same position.) If the hublock dials are manually turned from the AUTO to the LOCK position, and the high vacuum level is applied to the hublocks (by switching the MSS from 2WD to 4x4 HIGH or 4x4 LOW), the hublocks will be locked through the dial as well as through the internal spring mechanism. In this case, turning the hublock dials back to the AUTO position will leave the hublocks in (spring) locked mode until the lower vacuum level is applied to the hublocks (by switching the MSS from 4x4 or 4x4 LOW to the 4x2). (This is not an issue if the hublock dials have been in the AUTO position and the MSS has been switched from 4x4 HIGH or 4x4 LOW to 2WD at least once.) Alternatively, the hublock mechanism can be reset to free mode at any time by turning the hublock dial from AUTO to LOCK to AUTO at least 2 times. Hublock Operational State Locked position - Manual Override Free Mode (for Troubleshooting or Recreational Towing) Automatic Operation via ESOF Automatic Vacuum Control with MSS in 4x4 HIGH or 4x4 LOW Automatic Vacuum Control with MSS in 2WD Hublock Dial Switching Procedure Switch to the hublock dial to LOCK Switch the hublock dial from AUTO to LOCK and back to AUTO to least 2 times Switch the hublock dial to AUTO NOTE: This cycle will always be completed and cannot be interrupted by switching the MSS to 2WD. If vehicle speed goes below 5 MPH during the 45-second cycle and the MSS remains in 4x4 HIGH or 4x4 LOW, the locking cycle will repeat. Switch the hublock dial to AUTO PVH solenoid activated for 45 seconds/vacuum at knuckle is 216 mm (8.5 in) Hg or more. PVH solenoid vents for 6 seconds. NOTE: Switching the MSS to 4x4 HIGH or 4x4 LOW will interrupt this cycle. Switch the hublock dial to AUTO PVH solenoid activated for 15 seconds/vacuum at knuckle is 150 to 180 mm (5.9 to 7.1 in) Hg.
308-07A-4 Hublock Replacement Left- and right-side hublocks are not connected, other than by the common vacuum supply line. If a malfunction in either hublock is diagnosed, it should be installed as an individual unit; there is no need to balance an axle with new hublocks on both sides. It is highly unlikely that both hublocks are malfunctioning at the same time on a vehicle. If both sides appear to be malfunctioning, be sure to verify upstream integrity before installing new hublocks on both sides. Many system components are involved in the correct operation of the ESOF hubs. Before diagnosing the hublocks themselves as the cause of 4WD concerns, be sure to verify all related system components. 308-07A-4 After removing the hublock retaining ring, be sure not to use tools other than hands or grip gloves to remove the hublock. Damage may occur to either the paint or the function of the hublock. Pliers or locking Channel-Locks should be considered as a last resort, and will usually damage the hublock, making it necessary to install a new hublock. Carefully shake the U-joint while attempting to remove the hublock; this should reduce hublock-to-axle shaft spline friction and ease removal.
308-07A-5 Electronic Shift Vacuum Schematic 308-07A-5 Feature Inputs: Mode select switch (MSS) Vehicle speed (hardwired to 4x4 module via ABS) Encoder position inputs A, B, C or D Transmission neutral position (automatic transmission) Clutch apply signal (manual transmission) Brake ON/OFF (BOO - hardwired from brake pedal switch) Feature Outputs: Transfer case dual-cone synchronization clutch Transfer case shift motor and Hall-effect encoder assembly Transfer case shift motor relays Pulse vacuum hublock (PVH) solenoid assembly
308-07A-6 PVH vacuum pump (certain diesel applications only) Cluster indicators (hardwired to instrument cluster via 4x4 module) During 4x4 Initialization at Startup: The 4x4 module will verify the MSS position If the transfer case is not in the desired mode, the 4x4 module will attempt to perform a range shift. If input conditions for 4L are not present, then the module will either shift to or remain in 4H Once the transfer case is engaged, or is already in the correct mode, the PVH lock/unlock and/or lock solenoids will be energized If the MSS position is 2H, the PVH lock/unlock solenoid will be commanded to energize ONLY at speeds below 8 km/h (5 mph). Once this speed threshold is met, the solenoid will be de-energized. This procedure is to prevent ratcheting induced by an attempt to unlock an already unlocked hub For a Shift Attempt From 2H to 4H or 4L, the Following Sequence Occurs: 308-07A-6 After the 40 seconds have expired, the motor will make 10 more attempts to complete the shift. The motor will continue to repeat this sequence a total of 6 times (60 shift attempts) before ceasing operation. further shift attempts will be made, nor will any further MSS commands be recognized. The vehicle must be restarted for 4x4 function to be restored. If this occurs, DTC C1728 (for 2H to 4H attempts) or DTC C1729 (for 4H to 4L shift attempts) will be stored in memory If the vehicle is driven above 5 km/h (3 mph) during a 40-second rest period, the module will reattempt the shift strategy outlined previously. Generally, the transfer case will engage as the probability of gear teeth blockage is greatly reduced while rolling If no gear teeth blockage is present, the transfer case synchronizers bring the front driveshaft to same speed as rear driveshaft Shift fork completes movement and the 4x4 and (if 4L) Low Range lamp will illuminate. This ONLY occurs when the driveshafts are synchronized. If they are not, then the 4x4 lamp will not illuminate MSS is switched from 2H to 4H or 4L Once the 4x4 lamp is illuminated, the PVH lock For shift attempts into 4L: and lock/unlock solenoids are energized for 45 seconds, with approximately 62 kpa (9 psi) of the brake must be applied. vacuum or more at the hubs. The PVH lock transmission must be in NEUTRAL (or clutch sequence cannot be overridden at any time (a pedal applied). mode shift change back to 2H) vehicle speed must be below 8 km/h (5 mph). After 45 seconds have elapsed, the solenoids Shift motor moves range fork in transfer case, undergo a 6-second vent period, whereby no which engages dual-cone synchronizers commands to either the lock or lock/unlock If a blocked shift condition occurs, the shift motor solenoids are allowed, regardless of MSS position will perform 10 shift attempts (2H to 4H or 4H to If the vehicle is driven above 8 km/h (5 mph) the 4L) totaling 5 clockwise movements and 5 PVH lock and lock/unlock solenoids are counterclockwise movements with an approximate re-energized in the same manner, regardless of 1-second delay between each motor movement whether the hubs are engaged or the original attempt 45-second engagement timer has expired If, after 10 attempts, a shift is not completed, then the module will command a shift motor rest time of 40 seconds, before it attempts any further shifts For a Shift Attempt from 4L to 4H to 2H, the Following Sequence Occurs: 4x4 mode select switch is placed from 4H or 4L to 2H For shift attempts out of 4L: the brake must be applied. transmission must be in NEUTRAL (or clutch pedal applied). vehicle speed must be below 8 km/h (5 mph).
308-07A-7 Shift motor moves range fork in transfer case, Visual Inspection Chart which disengages dual-cone synchronizers Mechanical Electrical 308-07A-7 If a blocked shift condition occurs, the shift motor Front axle assembly Battery junction box will perform 10 shift attempts from 4H or 4L to Pulse vacuum hublocks (BJB) fuse 3 (30A) 2H to 4H or 4L to 2H totaling 5 clockwise (PVH) Central junction box movements and 5 counterclockwise movements Shift motor (CJB) fuse: Synchronization clutch 19 (10A) with an approximate 1-second delay between each Driveshaft and universal 27 (15A) motor movement attempt joints 33 (15A) If, after 10 attempts, a shift is not completed, then Vacuum leaks 45 (10A) the module will command a shift motor rest time Fluid leaks Wiring harness Matching tire sizes 4WD control module of 40 seconds, before it attempts any further shifts Transfer case (GEM) After the 40 seconds have expired, the motor will Shift relays make 10 more attempts to complete the shift. The Shift motor encoder assembly motor will continue to repeat this sequence a total Mode select switch of 6 times (60 shift attempts) before ceasing (MSS) operation. further shift attempts will be made, Connector(s) nor will any further MSS commands be PVH solenoid assembly recognized. The vehicle must be restarted for 4x4 Vacuum solenoid (diesel function to be restored. If this occurs, DTC 5728 only) Circuitry (for attempts between 2H and 4H) or DTC 5729 (for attempts between 4H and 4L) will be stored in memory. 3. If an obvious cause for an observed or reported If the vehicle is driven above 3 mph (5 km/h) concern is found, correct the cause (if possible) during a 40-second rest period, the module will before proceeding to the next step. reattempt a shift (4H to 2H only). Generally, the 4. If the cause is not visually evident, connect the transfer case will disengage as the probability of diagnostic tool to the data link connector and torque trapping is lower while rolling select the vehicle to be tested from the If no torque trapping is present, the transfer case diagnostic tool menu. If the diagnostic tool does synchronizers decouple the front driveshaft not communicate with the vehicle: Shift fork completes movement and de-energizes check that the program card is correctly 4x4, and if 4L, Low Range lamps. Once installed (if using NGS+). the 4x4 lamp is de-energized, the PVH check the connections to the vehicle. lock/unlock solenoid is energized for 15 seconds, check the ignition switch position. pulling approximately 41 kpa (6 psi) of vacuum at the hubs 5. If the diagnostic tool still does not communicate with the vehicle, refer to the diagnostic tool The PVH unlock sequence can be overridden at operating manual. any time such as a mode shift change back to 4H or 4L, relocking the hubs 6. Carry out the data link diagnostics test. If the diagnostic tool responds with: After 15 seconds, the solenoids undergo a 6-second vent period; the vent period can be SCP+, SCP-, UBP, CAN or ISO circuits overridden at any time by a shift attempt to 4H or fault; all electronic control units no 4L response/not equipped, refer to Section 418-00. Inspection and Verification response/not equipped for powertrain 1. Verify the customer concern. control module (PCM). Refer to Section 2. Visually inspect for obvious signs of 418-00 to diagnose module communication mechanical or electrical damage. problems. response/not equipped for 4WD control module, GO to Pinpoint Test G.
308-07A-8 308-07A-8 System passed, retrieve and record the 8. If no DTCs related to the concern are retrieved, continuous diagnostic trouble codes (DTCs), GO to the Symptom Chart. erase the continuous DTCs and carry out the self-test diagnostics for the 4WD control Four-Wheel Drive (4WD) Diagnostic Trouble module. Code (DTC) Index 7. If the DTCs retrieved are related to the concern, NOTICE: After repairing the cause of the 4WD go to the Four-Wheel Drive (4WD) Diagnostic system faults, the engine must be started in order Trouble Code (DTC) Index to continue to clear the 4WD control module DTCs. diagnostics. Four-Wheel Drive (4WD) Control Module Diagnostic Trouble Code (DTC) Index DTC Description Source Action B1317 Battery Voltage High 4WD Control REFER to Section 414-00. Module B1318 Battery Voltage Low 4WD Control REFER to Section 414-00. Module B1342 ECU is Defective 4WD Control CLEAR DTCs. REPEAT the self-test. If Module DTC B1342 is retrieved, INSTALL a new 4WD control module. REFER to Four Wheel Drive (4WD) Control Module in this section. CLEAR the DTCs. REPEAT the self-test. B1355 Ignition RUN Circuit Failure 4WD Control CHECK CJB fuse 45 (10A) for an open. Module If the fuse is blown, GO to Pinpoint Test J. If missing, INSTALL a new fuse. TEST the system for normal operation. B1359 Ignition RUN/ACC Circuit Failure 4WD Control CHECK CJB fuse 33 (15A) for an open. Module If the fuse is blown, GO to Pinpoint Test J. If missing, INSTALL a new fuse. TEST the system for normal operation. B1366 Ignition START Circuit Short to Ground 4WD Control REFER to Section 211-05. Module B1483 Brake Pedal Input Circuit Failure 4WD Control GO to Pinpoint Test L. Module B1485 Brake Pedal Input Circuit Short to 4WD Control GO to Pinpoint Test L. Battery Module B2477 Module Configuration Failure 4WD Control REFER to Section 418-01. (Unconfigured, Incorrect or Rejected) Module C1728 Transfer Case Unable to Transition 4WD Control GO to Pinpoint Test J. Between 2H and 4H Module C1729 Transfer Case Unable to Transition 4WD Control GO to Pinpoint Test L. Between 4H and 4L Module P0500 Vehicle Speed Sensor (VSS) Malfunction 4WD Control GO to Pinpoint Test L. Module P1804 Transmission 4-Wheel Drive High 4WD Control GO to Pinpoint Test H. Indicator Circuit Failure Module P1806 Transmission 4-Wheel Drive High 4WD Control GO to Pinpoint Test H. Indicator Short Circuit to Battery Module P1808 Transmission 4-Wheel Drive Low 4WD Control GO to Pinpoint Test H. Indicator Circuit Failure Module
308-07A-9 Four-Wheel Drive (4WD) Control Module Diagnostic Trouble Code (DTC) Index DTC Description Source Action P1810 Transmission 4-Wheel Drive Low 4WD Control GO to Pinpoint Test H. Indicator Short Circuit to Battery Module P1812 Transmission 4-Wheel Drive Mode Select 4WD Control GO to Pinpoint Test Q. Switch Circuit Open Module P1815 Transmission 4-Wheel Drive Mode Select 4WD Control GO to Pinpoint Test Q. Switch Short Circuit to Ground Module P1819 Transmission Neutral Safety Switch Short 4WD Control GO to Pinpoint Test L. Circuit to Ground Module P1820 Transmission Transfer Case Clockwise 4WD Control GO to Pinpoint Test K. Shift Relay Coil Circuit Failure Module P1822 Transmission Transfer Case Clockwise 4WD Control GO to Pinpoint Test K. Shift Relay Coil Short Circuit to Battery Module P1828 Transmission Transfer Case 4WD Control GO to Pinpoint Test K. Counterclockwise Shift Relay Coil Module Circuit Failure P1830 Transmission Transfer Case 4WD Control GO to Pinpoint Test K. Counterclockwise Shift Relay Coil Short Module Circuit to Battery 308-07A-9 P1832 Transmission Transfer Case Differential 4WD Control CHECK CJB fuse 27 (15A) for an open. Lock-Up Solenoid Circuit Failure Module If the fuse is OK, GO to Pinpoint Test I. If missing, INSTALL a new fuse. TEST the system for normal operation. P1834 Transmission Transfer Case Differential 4WD Control GO to Pinpoint Test I. Lock-Up Solenoid Short Circuit to Module Battery P1865 Transmission Transfer Case Contact Plate 4WD Control GO to Pinpoint Test J. Power Short to Ground Module P1866 Transmission Transfer Case System 4WD Control GO to Pinpoint Test J. Concern Servicing Required Module P1867 Transmission Transfer Case Contact Plate 4WD Control GO to Pinpoint Test J. General Fault Module P1876 Transmission Transfer Case 2-Wheel 4WD Control CHECK CJB fuse 27 (15A) for an open. Drive Solenoid Circuit Failure Module If the fuse is blown, GO to Pinpoint Test I. If missing, INSTALL a new fuse. TEST the system for normal operation. P1877 Transmission Transfer Case 2-Wheel 4WD Control GO to Pinpoint Test I. Drive Solenoid Circuit Short to Battery Module
308-07A-10 Symptom Chart 308-07A-10 Symptom Chart Electronic Shift Condition Possible Sources Action communication with the Diagnostic tool GO to Pinpoint Test G. 4WD control module Data link connector (DLC) 4WD control module Circuitry The instrument cluster 4x4 Instrument cluster GO to Pinpoint Test H. and Low Range indicators do Circuitry not operate correctly/do not 4WD control module operate The vehicle does not shift Mode select switch (MSS) GO to Pinpoint Test J. between 2H and 4H modes Transfer case correctly Transfer case clutch Pulse vacuum hublocks (PVH) 4WD control module Circuitry The vehicle does not shift Transfer case GO to Pinpoint Test L. between 4H and 4L modes Mode select switch correctly 4WD control module Transmission drag 4WD does not engage at Transfer case synchronizer GO to Pinpoint Test M. speed correctly 4WD control module Pulse vacuum hublocks (PVH) The front axle does not Pulse vacuum hublocks GO to Pinpoint Test I. engage/disengage correctly (PVH) PVH solenoid assembly Circuitry Vacuum leaks 4WD control module Front axle assembly The 4x4 system jumps out of Transfer case GO to Pinpoint Test N. gear PVH system Mode select switch Straightline driveline wind-up Tire inflation pressure GO to Pinpoint Test O. Tire and wheel size Tire wear Axle ratio Clunking noise during 4WD Vehicle speed GO to Pinpoint Test M engagement, especially at Torque to the front axle high speeds
308-07A-11 Symptom Chart Electronic Shift 308-07A-11 Condition Possible Sources Action The transfer case makes noise Tire inflation pressure MAKE SURE that all tires Tire and wheel size and wheels are the same size and that the inflation pressures are correct. Tire tread wear CHECK tire tread wear to see if there is more than 0.15 mm (0.06 in) difference in tread wear between front and rear. INTERCHANGE one front wheel and one rear wheel. ROAD TEST again. Internal components OPERATE the vehicle in all transmission gears. If there is noise in the transmission in NEUTRAL, or in some gears and not in others, REMOVE and REPAIR the transmission. REFER to Section 307-01B. If there is noise in all gears, DISASSEMBLE the transfer case. REFER to Section 308-07B. CHECK the planetary gears, the bearings, the upper and lower drive sprockets and drive chain for damage. INSTALL new parts as necessary. Fluid level FILL with automatic transmission fluid. REFER to Section 308-07B. Unable to duplicate customer 4x4 system and/or related Carry out the Electronic Shift concern components on the Fly (ESOF) Functional Test. GO to Pinpoint Test P.
308-07A-12 4x4 Module (GEM) C281a 308-07A-12 Pin Number(s) Circuit Designation/Description rmal Condition/Measurement 1 4x4 module (GEM) power circuit 1306 Main power connection to the 4x4 module (PK/WH) (GEM), shared with pin. 2. Hot at all times, 9 volts or greater between 4x4 module (GEM) and ground. 10,000 ohms or greater between the 4x4 module (GEM) and ground with the 4x4 module (GEM) disconnected. 2 4x4 module (GEM) power circuit 1306 Main power connection to the 4x4 module (PK/WH) (GEM), shared with pin. 1. Hot at all times, 9 volts or greater between 4x4 module (GEM)) and ground. 10,000 ohms or greater between the 4x4 module (GEM) and ground with the 4x4 module (GEM) disconnected. 3 4x4 module (GEM) ground circuit 57 (BK) Main ground connection to the 4x4 module (GEM). 1 volt or less between the 4x4 module (GEM) and ground. 5 ohms or less between the 4x4 module (GEM) and ground with the 4x4 module (GEM) disconnected. 4 Brake on/off input (BOO) circuit 810 Circuit required for shifting to low range (RD/LG) (4L). 9 volts or greater when brake pedal is depressed. <1 volt when brake is not applied. 10,000 ohms or greater between the 4x4 module (GEM) and ground with the 4x4 module (GEM) disconnected. 5 ohms or less between the 4x4 module (GEM) and brake ON/OFF (BOO) switch. 5 Ignition RUN/START circuit 640 (RD/YE) Hot when in RUN/START. 9 volts or greater between the 4x4 module (GEM) and ground with the 4x4 module (GEM) disconnected. 10,000 ohms or greater between the 4x4 module (GEM) and ground with the 4x4 module (GEM) disconnected. 6 Ignition RUN/ACC circuit 1002 (BK/PK) Hot when in RUN/ACC. 9 volts or greater between the 4x4 module (GEM) and ground with the 4x4 module (GEM) disconnected. 10,000 ohms or greater between the 4x4 module (GEM) and ground with the 4x4 module (GEM) disconnected.
308-07A-13 Pin Number(s) Circuit Designation/Description rmal Condition/Measurement 308-07A-13 7 Transfer case shift motor encoder power Provides power to shift motor encoder from circuit 976 (OG) 4x4 module (GEM). 9 volts or greater between the 4x4 module (GEM) and ground with the 4x4 module (GEM) connected. 10,000 ohms or greater between the 4x4 module (GEM) and ground with the 4x4 module (GEM) disconnected. 5 ohms or less between the 4x4 module (GEM) and shift motor encoder. 8 Transfer case shift motor encoder return 4x4 module-provided main ground return (ground) circuit 3659 (BK/PK) path to the shift motor encoder. 10,000 ohms or greater between the 4x4 module (GEM) and ground with the 4x4 module (GEM) and the transfer case encoder disconnected. 5 ohms or less between the 4x4 module (GEM) and ground with the 4x4 module (GEM) and transfer case encoder connected. 5 ohms or less between the 4x4 module (GEM) and the transfer case encoder. 9 Transfer case shift motor encoder signal One of 4 channels which provide transfer position A 771 (VT/YE) case shift motor position. 0 volts between transfer case and ground when in 2H with the 4x4 module (GEM) and the transfer case encoder connected. 9 volts or greater between the transfer case and ground when in 4H or 4L with the 4x4 module (GEM) and transfer case encoder connected. 10,000 ohms or greater between the 4x4 module (GEM) and ground with the 4x4 module (GEM) and the transfer case disconnected. 5 ohms or less between the 4x4 module (GEM) and the transfer case. 10 Transfer case shift motor encoder signal One of 4 channels which provide transfer position B 764 (BN/WH) case shift motor position. 0 volts between transfer case and ground when in 2H with the 4x4 module (GEM) and the transfer case encoder connected. 9 volts or greater between the transfer case and ground when in 4L with the 4x4 module (GEM) and transfer case encoder connected. 10,000 ohms or greater between the 4x4 module (GEM) and ground with the 4x4 module (GEM) and the transfer case disconnected. 5 ohms or less between the 4x4 module (GEM) and the transfer case.
308-07A-14 Pin Number(s) Circuit Designation/Description rmal Condition/Measurement 308-07A-14 11 Transfer case shift motor encoder signal One of 4 channels which provide transfer position C 770 (WH) case shift motor position. 9 volts or greater between transfer case and ground when in 2H with the 4x4 module (GEM) and the transfer case encoder connected. 0 volts between the transfer case and ground when in 4L with the 4x4 module (GEM) and transfer case encoder connected. 10,000 ohms or greater between the 4x4 module (GEM) and ground with the 4x4 module (GEM) and the transfer case disconnected. 5 ohms or less between the 4x4 module (GEM) and the transfer case. 12 Transfer case shift motor encoder signal One of 4 channels which provide transfer position D 763 (OG/WH) case shift motor position. 0 volts between transfer case and ground when in 2H, 4H or 4L with the 4x4 module (GEM) and the transfer case encoder connected. 10,000 ohms or greater between the 4x4 module (GEM) and ground with the 4x4 module (GEM) and the transfer case disconnected. 5 ohms or less between the 4x4 module (GEM) and the transfer case.
308-07A-15 4x4 Module (GEM) C281b 308-07A-15 Pin Number(s) Circuit Designation/Description rmal Condition/Measurement 1 Pulse vacuum hublock (PVH) LOCK 4x4 module-provided ground path for LOCK solenoid control circuit 145 (GY/BK) coil in PVH solenoid when vehicle is placed from 2H to 4H/4L. Ground path provided for approximately 45 seconds after a 2H to 4H/4L shift is required by the driver. 10,000 ohms or greater between the 4x4 module (GEM) and ground with the 4x4 module (GEM) and PVH solenoid disconnected. 5 ohms or less between the 4x4 module (GEM) and the PVH LOCK Solenoid. 2 4x4 mode select switch (MSS) power circuit Hot in run, 9 volts or greater between 4x4 780 (DB) module (GEM) and ground with 4x4 module (GEM) C281b connected and MSS C284 disconnected. Approximately 7.5V between the 4x4 module (GEM) and ground with the 4x4 module (GEM) connected and MSS in 2H. Approximately 5.5 volts between the 4x4 module (GEM) and ground with the 4x4 module (GEM) connected and MSS in 4H. Approximately 3.7 volts between the 4x4 module (GEM) and ground with the 4x4 module (GEM) and MSS connected and MSS in 4L. 10,000 ohms or greater between the 4x4 module (GEM) and ground with the 4x4 module (GEM) and MSS disconnected. 5 ohms or less between the 4x4 module (GEM) and MSS. 3 Vehicle speed signal (VSS) from ABS Circuit required for shifting to low range module 679 (GY/BK) (4L). Speed-dependent square wave input. Approximately 0 volts between 4x4 module (GEM) and ground at 0 kph. Voltage increases as vehicle speed increases. VSS must be 5kph or less for shifts to low range (4L). 10,000 ohms or greater between the 4x4 module (GEM) and ground with the 4x4 module (GEM) and ABS module disconnected. 5 ohms or less between the 4x4 module (GEM) and the ABS module.
308-07A-16 Pin Number(s) Circuit Designation/Description rmal Condition/Measurement 308-07A-16 4 Transmission neutral signal (or clutch apply Circuit required for shifting to low range signal) 463 (RD/WH) from PCM (4L). 10,000 ohms or greater between the 4x4 module (GEM) and ground with the 4x4 module (GEM) disconnected and transmission NOT in NEUTRAL (or clutch pedal NOT applied). 5 ohms or less between the 4x4 module (GEM) and ground with the 4x4 module (GEM) disconnected and transmission in NEUTRAL (or clutch pedal applied). 5 ohms or less between the 4x4 module (GEM) and the PCM. 5 Transfer case shift motor clockwise rotation Circuit provides the module-switched ground (CW) relay control circuit 782 (BN/WH) path for the clockwise rotation relay. 10,000 ohms or greater between the 4x4 module (GEM) and ground with the 4x4 module (GEM) disconnected. 5 ohms or less between the 4x4 module (GEM) and ground when the 4x4 module is connected and the transfer case is shifted from 2H to 4H to 4L. 5 ohms or less between the 4x4 module (GEM) and clockwise rotation relay. 6 Transfer case shift motor counterclockwise Circuit provides the module-switched ground rotation relay control circuit 781 (OG/LB) path for the counterclockwise rotation relay. 10,000 ohms or greater between the 4x4 module (GEM) and ground with the 4x4 module (GEM) disconnected. 5 ohms or less between the 4x4 module (GEM) and ground when the 4x4 module (GEM) is connected and the transfer case is shifted from 4L to 4H to 2H. 5 ohms or less between the 4x4 module (GEM) and counterclockwise rotation relay. 7 Pulse vacuum hublock (PVH) Circuit provides the module-switch ground LOCK/UNLOCK solenoid control circuit 605 path for the LOCK/UNLOCK coil in the (RD) PVH solenoid when vehicle is placed from 2H to 4H/4L to 2H. Ground path provided for approximately 45 seconds after a 2H to 4H/4L shift is requested by the drive. Ground path is provided for approximately 15 seconds after a 4H/4L to 2H shift is requested. 10,000 ohms or greater between the 4x4 module (GEM) and ground with the 4x4 module (GEM) and the PVH solenoid disconnected. 5 ohms or less between the 4x4 module (GEM) and the PVH Solenoid. 8 t Used 9 4x4 mode select switch (MSS) signal return 4x4 module-provided ground return path for circuit 465 (WH/LB) MSS signal. 10,000 ohms or greater between the 4x4 module (GEM) and ground with the 4x4 module (GEM) and MSS disconnected. 5 ohms or less between the 4x4 module and ground with the 4x4 module (GEM) and MSS connected. 5 ohms or less between the 4x4 module (GEM) and MSS.
308-07A-17 Pin Number(s) Circuit Designation/Description rmal Condition/Measurement 308-07A-17 10 Diagnostic data link connector circuit 70 10,000 ohms or greater between the 4x4 (LB/WH) module (GEM) and ground with the 4x4 module (GEM) disconnected and the NGS/WDS unplugged from the DLC. 5 ohms or less between the 4x4 module (GEM) and the DLC. 11 Instrument cluster Low Range (4L) lamp 4x4 module-provided ground path for LOW control circuit 975 (BN/YE) RANGE lamp in instrument cluster when transfer case is shifted to 4L. 10,000 ohms or greater between the 4x4 module (GEM) and ground with the 4x4 module (GEM) disconnected. 5 ohms or less between the 4x4 module (GEM) and ground when transfer case is placed in 4L with the 4x4 module (GEM) and instrument cluster connected. 5 ohms or less between the 4x4 module (GEM) and the instrument cluster. 12 Instrument cluster 4x4 (4H) lamp control Module-provided ground path for 4x4 circuit 210 (LB) lamp in instrument cluster when transfer case is shifted to 4H OR 4L. 10,000 ohms or greater between the 4x4 module (GEM) and ground with the 4x4 module (GEM) disconnected. 5 ohms or less between the 4x4 module (GEM) and ground when transfer case is placed in 4H OR 4L with the 4x4 module (GEM) and instrument cluster connected. 5 ohms or less between the 4x4 module (GEM) and the instrument cluster. Mode Select Switch (MSS) C284 Pin Number(s) Circuit Designation/Description rmal Condition/Measurement 1 Nighttime illumination ground circuit 57 (BK) 2 4WD Mode select switch (MSS) signal Provides ground return path for MSS signal. return circuit 465 (WH/LB) 10,000 ohms or greater between the 4.4 module (GEM) and ground with the MSS disconnected and the 4x4 module (GEM) connected. 5 ohms or less between the 4x4 module (GEM) and MSS.
308-07A-18 Pin Number(s) Circuit Designation/Description rmal Condition/Measurement 308-07A-18 3 4WD Mode select switch (MSS) signal Hot in RUN. 9 volts or greater between the circuit 780 (DB) MSS and ground with the MSS disconnected. Approx 7.5V between the MSS and ground with the MSS connected and in 2H. Approximately 5.5 volts between the MSS and ground with the MSS connected and in 4H. Approx 3.7 volts between the MSS and ground with the MSS connected and in 4L. 10,000 ohms or greater between the 4x4 module (GEM) and ground with the 4.4 module (GEM) and MSS disconnected. 5 ohms or less between the 4x4 module (GEM) and MSS. 4 Nighttime illumination power circuit 19 (LB/RD) Transfer Case Encoder C350a Pin Number(s) Circuit Designation/Description rmal Condition/Measurement 1 Transfer case encoder signal position D 763 One of 4 channels which provide transfer (OG/WH) case shift motor position. 0 volts between transfer case and ground when in 2H, 4H or 4L with the 4x4 module (GEM) and the transfer case encoder connected. 10,000 ohms or greater between the transfer case encoder and ground with the 4x4 module (GEM) and the transfer case encoder disconnected. 5 ohms or less between the 4x4 module (GEM) and the transfer case encoder. 2 Transfer case encoder power supply circuit Hot at all times. 9 volts or greater between 976 (OG) the transfer case encoder and ground with the transfer case encoder disconnected. 10,000 ohms or greater between the transfer case and ground with the transfer case encoder and the 4x4 module (GEM) disconnected. 5 ohms or less between the 4x4 module (GEM) and transfer case encoder.
308-07A-19 Pin Number(s) Circuit Designation/Description rmal Condition/Measurement 308-07A-19 3 Transfer case encoder signal position B 764 One of 4 channels which provide transfer (BN/WH) case shift motor position. 0 volts between transfer case and ground when in 2H or 4H with the 4x4 module (GEM) and the transfer case encoder connected. 9 volts or greater between the transfer case encoder and ground when in 4L with the 4x4 module (GEM) and transfer case encoder connected. 10,000 ohms or greater between the 4x4 module (GEM) and ground with the 4x4 module (GEM) and the transfer case disconnected. 5 ohms or less between the 4x4 module (GEM) and the transfer case. 4 Transfer case encoder signal return 3659 10,000 ohms or greater between the 4x4 (BK/PK) module (GEM) and ground with the 4x4 module (GEM) and the transfer case disconnected. 5 ohms or less between the 4x4 module (GEM) and the transfer case. 5 Transfer case encoder signal position A 771 One of 4 channels which provide transfer (VT/YE) case shift motor position. 0 volts between transfer case encoder and ground when in 2H with the 4x4 module (GEM) and the transfer case encoder connected. 9 volts or greater between the transfer case and ground when in 4H or 4L with the 4x4 module (GEM) and transfer case encoder connected. 10,000 ohms or greater between the transfer case encoder and ground with the 4x4 module (GEM) and the transfer case disconnected. 5 ohms or less between the 4x4 module (GEM) and the transfer case. 6 Transfer case encoder signal position C 770 One of 4 channels which provide transfer (WH) case shift motor position. 9 volts or greater between transfer case and ground when in 2H or 4H with the 4x4 module (GEM) and the transfer case encoder connected. 0 volts between the transfer case and ground when in 4L with the 4x4 module (GEM) and transfer case encoder connected. 10,000 ohms or greater between the transfer case encoder and ground with the 4x4 module (GEM) and the transfer case disconnected. 5 ohms or less between the 4x4 module (GEM) and the transfer case. Transfer Case Shift Motor C350b
308-07A-20 Pin Number(s) Circuit Designation/Description rmal Condition/Measurement 308-07A-20 1 Transfer case counterclockwise rotation 9 volts or greater between the shift motor power supply circuit 778 (OG) and ground when a counterclockwise range shift is performed. 10,000 ohms or greater between the counterclockwise rotation relay and ground with the counterclockwise relay and transfer case disconnected. 5 ohms or less between the shift motor and the counterclockwise relay when a clockwise range shift is performed. 5 ohms or less between the counterclockwise relay and the transfer case. 0.1 20 ohms between shift motor pin. 1 and. 2. 2 Transfer case shift motor clockwise rotation 9 volts or greater between the shift motor power supply circuit 777 (YE) and ground when a clockwise range shift is performed. 10,000 ohms or greater between the clockwise rotation relay and ground with the clockwise relay and transfer case disconnected. 5 ohms or less between the shift motor and the clockwise relay when a counterclockwise range shift is performed. 5 ohms or less between the clockwise relay and the transfer case. 0.1 20 ohms between shift motor pin. 1 and. 2.
308-07A-21 Pulse Vacuum Hublock (PVH) Solenoid C1247 308-07A-21 Pin Number(s) Circuit Designation/Description rmal Condition/Measurement 1 PVH LOCK solenoid control circuit 145 4x4 module-controlled ground path to the (GY/BK) LOCK solenoid. Ground path is enabled for approximately 45 seconds after a mode switch change is made from 2H to 4H/4L. 10,000 ohms or greater between the PVH solenoid and ground with the PVH solenoid and the 4x4 module (GEM) disconnected. 5 ohms or less between the PVH solenoid and the 4x4 module (GEM). 2 PVH solenoid power supply circuit 295 Hot when in RUN. 9 volts or greater (LB/PK) between the PVH solenoid and ground. 10,000 ohms or greater between the PVH solenoid and ground with the PVH solenoid disconnected. 10,000 ohms or greater between the PVH solenoid and ground with the PVH solenoid and the 4x4 module (GEM) disconnected. 3 PVH LOCK/UNLOCK solenoid control Provides a module-controlled ground path to circuit 605 (RD) the LOCK/UNLOCK solenoid. Ground path is enabled for approximately 15 seconds after a mode switch change is made from 4L/4H to 2H. Ground path is enabled for approximately 45 seconds after a mode switch change is made from 2H to 4H/4L. 10,000 ohms or greater between the PVH solenoid and ground with the PVH solenoid and the 4x4 module (GEM) disconnected. 5 ohms or less between the PVH solenoid and the 4x4 module (GEM). Shift Motor Clockwise Rotation Relay (Low-to-High) C1129
308-07A-22 Pin Number(s) Circuit Designation/Description rmal Condition/Measurement 308-07A-22 85 Transfer case shift motor clockwise rotation 4x4 module-controlled ground path to the relay control circuit 782 (BN/WH) clockwise shift relay. This ground path is only provided during a range shift attempt. 10,000 ohms or greater between the clockwise relay and ground with the CW relay and the 4x4 module (GEM) disconnected. 5 ohms or less between the clockwise relay and the 4x4 module (GEM). 86 Transfer case shift motor clockwise rotation Provides power to the clockwise rotation relay power supply circuit 704 (DG/LG) relay. Hot at all times. 9 volts or greater between the clockwise relay and ground. 10,000 ohms or greater between the clockwise relay and ground with the clockwise relay disconnected. 87 Transfer case shift motor clockwise rotation Provides power to the clockwise shift relay relay coil power supply circuit 704 (DG/LG) coil. Hot at all times. 9 volts or greater between the clockwise relay and ground. 10,000 ohms or greater between the clockwise rotation relay and ground with the clockwise relay disconnected. 87A Transfer case shift motor clockwise rotation Provides permanent chassis ground return relay ground input circuit 57 (BK) path for shift motor during a counterclockwise shift. 5 ohms or less between clockwise relay and ground at all times. 30 Transfer case shift motor clockwise rotation Provides power to the shift motor during relay power/ground output circuit 777 (YE) clockwise motor movement. Provides ground to shift motor during counterclockwise motor movement. 9 volts or greater between the clockwise relay and ground during a range shift attempt. 5 ohms or less between the clockwise relay and ground with the clockwise relay disconnected. 5 ohms or less between the clockwise relay and the transfer case.
308-07A-23 Shift Motor Counterclockwise Rotation Relay (High-to-Low) C1173 308-07A-23 Pin Number(s) Circuit Designation/Description rmal Condition/Measurement 85 Transfer case shift motor counterclockwise Provides a module-controlled ground path to rotation relay control circuit 781 (OG/LB) the counterclockwise shift relay. This ground path is only provided during a range shift attempt. 10,000 ohms or greater between the counterclockwise relay and ground with the counterclockwise relay and the 4x4 module (GEM) disconnected. 5 ohms or less between the counterclockwise relay and the 4x4 module (GEM). 86 Transfer case shift motor counterclockwise Provides power to the counterclockwise rotation relay power supply circuit 704 rotation relay. Hot at all times. 9 volts or (DG/LG) greater between the counterclockwise relay and ground. 10,000 ohms or greater between the clockwise relay and ground with the clockwise relay disconnected. 87 Transfer case shift motor counterclockwise Provides power to the counterclockwise shift rotation relay coil power supply circuit 704 relay coil. Hot at all times. 9 volts or greater (DG/LG) between the counterclockwise relay and ground. 10,000 ohms or greater between the counterclockwise rotation relay and ground with the counterclockwise relay disconnected. 87A Transfer case shift motor counterclockwise Provides permanent chassis ground return rotation relay ground input circuit 57 (BK) path for shift motor during a clockwise shift. 5 ohms or less between counterclockwise relay and ground at all times. 30 Transfer case shift motor counterclockwise Provides power to the shift motor during rotation relay power/ground output circuit counterclockwise motor movement. Provides 778 (OG) ground to shift motor during clockwise motor movement. 9 volts or greater between the counterclockwise relay and ground during a range shift attempt. 10,000 ohms or greater between the counterclockwise relay and ground with the counterclockwise relay disconnected. 5 ohms or less between the counterclockwise relay and the transfer case. Pinpoint Tests Pinpoint Test G: Communication With the 4x4 Module (GEM) Refer to Wiring Diagrams Cell 34 for schematic and connector information. rmal Operation In order for the 4WD control module (GEM) to communicate with the diagnostic tool, the operating voltage required to supply the 4WD control module is in a range between 9 and 16 volts.
308-07A-24 Possible Causes Central junction box (CJB) fuses: Power supply circuits: 19 (10A) 1306a (PK/WH) 45 (10A) 1306c (PK/WH) 33 (15A) Ignition circuits: Charging system 295 (LB/PK) Battery 640 (RD/YE) 1002 (BK/PK) 308-07A-24 G1 G2 PINPOINT TEST G: NO COMMUNICATION WITH THE 4X4 MODULE NOTICE: Use the Flex Probe Kit for all test connections to prevent damage to the wiring terminals. Do not use standard multimeter probes. CHECK FOR DIAGNOSTIC TOOL COMMUNICATION WITH THE 4X4 MODULE Verify diagnostic tool communication with the vehicle 4WD control module. If using the WDS, follow the directions and carry out the network test. If using NGS+, verify that the vehicle and engine selection information is correct. REFER to the appropriate diagnostic tool WDS: Does the network test pass for the 4WD control manual for further diagnosis. module? NGS+ : Are the vehicle and engine selections correct? GO to G2. CHECK IGNITION SWITCH STATUS PID Key in ON position. Monitor the ignition switch status PID. G3 Ignition Switch Position PID Expected Value OFF IGN O/L OFF ACCESSORY IGN ACC ACCY GO to G3. RUN IGN R RUN START IGN S START CHECK the ignition switch. REFER to Section 303-06A for gasoline engines or Section 303-06B for diesel engines. After Do the ignition switch PIDs match the ignition switch the fault is repaired, CLEAR the DTC. positions? REPEAT the self-test. CHECK FOR VOLTAGE INPUT TO THE 4X4 MODULE (GEM) Disconnect: 4WD Control Module C281a. Key in ON position. Measure the voltage between 4WD control module C281a and ground as follows: C281a Pin Circuit 1 1306 (PK/WH) 2 1306 (PK/WH) 5 640 (RD/YE) 6 1002 (BK/PK)
308-07A-25 G3 PINPOINT TEST G: NO COMMUNICATION WITH THE 4X4 MODULE CHECK FOR VOLTAGE INPUT TO THE 4X4 MODULE (GEM) 308-07A-25 G4 G5 G6 G7 GO to G7. Are the voltages at each pin greater than 9 volts? GO to G4. CHECK THE CENTRAL JUNCTION BOX (CJB) MINI-FUSES Check CJB mini-fuses: 19 (10A). GO to G5. 45 (10A). 33 (15A). INSTALL new fuses. REPAIR the circuits Are the fuses okay? as necessary. REPEAT the self-test. CHECK FOR BATTERY VOLTAGE AT THE BJB AND CJB POWER INPUT FUSE CAVITIES Key in ON position. Measure the voltage between CJB input side fuse cavities and ground: 19 (10A). 45 (10A). GO to G7. 33 (15A). Are the voltages greater than 9 volts? GO to G6. CHECK THE BATTERY VOLTAGE WITH THE ENGINE RUNNING Start the engine. Measure the battery voltage at the positive battery terminal. GO to G7. Is the voltage greater than 9 volts? CHECK the charging system. REFER to Section 414-00. CHECK THE GROUND CIRCUIT FOR AN OPEN Disconnect the battery ground cable. Refer to section Section 414-00 Disconnect: 4WD control module (GEM) C281a. Measure the resistance between C281a-3, circuit 57 (BK) and ground. GO to G8. Is the resistance less than 5 ohms? REPAIR the circuit. REPEAT the self-test.
308-07A-26 G8 PINPOINT TEST G: NO COMMUNICATION WITH THE 4X4 MODULE CHECK FOR A FLOATING GROUND Measure the voltage between C281a-3, circuit 57 (BK) and ground. 308-07A-26 G9 REPAIR the circuit. REPEAT the self-test. Is voltage (greater than 1V) present? GO to G9. CHECK THE 4X4 MODULE CONNECTOR Disconnect the 4WD control module (GEM) connectors C281a and C281b. REPAIR or CLEAN the connector(s) as CHECK for corrosion and/or pushed out pins. necessary. Reconnect and REPEAT the Is the connector corroded and/or damaged? self-test. INSTALL a new 4WD control module (GEM). REFER to Four Wheel Drive (4WD) Control Module. TEST the system for normal operation. Pinpoint Test H: The Instrument Cluster 4x4 And Low Range Indicators Do t Operate Correctly/Do t Operate rmal Operation The 4x4 and Low Range indicator status is transmitted to the instrument cluster via independent hardwired ground paths from the 4x4 module through circuits 975 (BN/YE) and 210 (LB). A steady indicator is displayed whether the vehicle is in 4H or 4L, according to the driver selection. Indicators do not flash under any circumstances. When the vehicle is in 4L, the 4x4 and Low Range indicator circuits are displayed. When the 4x4 system is in 4H, only the 4x4 indicator circuit is displayed. indicators are displayed when the transfer case is in 2H or NEUTRAL mode. Possible Causes 4x4 system fault 4x4 indicator circuit: 4L 975 (BN/YE) 4H 210 (LB (at connector 281a), 210 (TN/RD) (at connector C220b) 4WD control module Instrument cluster H1 PINPOINT TEST H: THE INSTRUMENT CLUSTER 4X4 AND LOW RANGE INDICATORS DO NOT OPERATE CORRECTLY/DO NOT OPERATE CHECK THE 4X4 AND LOW RANGE INDICATOR PROVE-OUT Key in ON position. Do the 4x4 indicators prove-out correctly? GO to H2. CHECK the instrument cluster for faults. Refer to Section 413-01.