DIAGNOSIS AND TESTING

2000 Lincoln Town Car - Steering > Steering System Service > DIAGNOSIS AND TES... Page 1 of 40 2000 Lincoln Town Car : Steering > Steering System Service > DIAGNOSIS AND TESTING DIAGNOSIS AND TESTING SECTION 211-00: Steering System General Information 2000 Town Car Workshop Manual DIAGNOSIS AND TESTING Procedure revision date: 11/12/2003 STEERING SYSTEM Special Tool(s) Dial Thermometer 0-220 F 023-R0007 or equivalent 73III Automotive Meter 105-R0057 or equivalent Power Steering Analyzer 211-F001 (014-00207) or equivalent Gauge, Spring Tension 211-034 (T74P-3504-Y)

2000 Lincoln Town Car - Steering > Steering System Service > DIAGNOSIS AND TES... Page 2 of 40 DIS/EDIS Tach Adapter 418-F102 (007-00061) or equivalent Tie Rod End Remover 211-001 (TOOL -3290-D) or equivalent Worldwide Diagnostic System (WDS) 418-F224, New Generation STAR (NGS) Tester 418-F052, or equivalent diagnostic tool with appropriate adapter cable Material Item Mercon Multi-Purpose (ATF) Transmission Fluid XT-2-QDX Specification - Inspection and Verification Verify the customer concern. 2. Visually inspect for obvious signs of mechanical and electrical damage. Visual Inspection Chart Mechanical Electrical Fluid level Open fuses: Tire pressure Fuse 8 (10A) in the fuse junction panel Tires Drive belt Drive belt tensioner Steering column alignment Fuse 17 (10A) in the power distribution box Circuitry, connections open, grounding or shorting

2000 Lincoln Town Car - Steering > Steering System Service > DIAGNOSIS AND TES... Page 3 of 40 Mechanical Tie rod ends components Steering column shaft U-joints Intermediate shaft bolts Power steering reservoir baffle Power steering reservoir filter Power steering pressure lines, fittings or O-rings Power steering return hoses and clamps Steering gear Power steering pump Electrical Steering wheel rotation sensor Power steering pump actuator valve Rear air suspension control module Data link connector 3. If the fault is not visually evident, connect the diagnostic tool to the data link connector (DLC) located beneath the instrument panel and select the vehicle to be tested from the diagnostic tool menu. If the diagnostic tool does not communicate with the vehicle: check that the program card is correctly installed. check the connections to the vehicle. check the ignition switch position. 4. If the diagnostic tool still does not communicate with the vehicle, refer to the diagnostic tool manual. 5. Carry out the DATA LINK DIAGNOSTIC TEST. If the diagnostic tool responds with: CKT914, CKT915, or CKT70 = ALL ECUS NO RESP/NOT EQUIP, refer to Module Communications Network. NO RESP/NOT EQUIP for air suspension control module, Go To Pinpoint Test A. SYSTEM PASSED, retrieve and record the continuous diagnostic trouble codes (DTCs), erase the continuous DTCs and carry out self-test diagnostics for the air suspension control module. 6. If the DTCs retrieved are related to the concern, go to Diagnostic Trouble Code (DTC) Index to continue diagnostics. 7. If no DTCs related to the concern are retrieved, proceed to the next step to continue diagnostics. 8. NOTE: The 3 areas that should be inspected for possible contamination are the power steering reservoir filter, flow control and pressure relief valve in the pump and check valve in the inlet port on the power steering gear (if equipped). Inspect the power steering fluid for the following conditions: Aerated or foamy: Purge the power steering system. Refer to Power Steering System Purging in this section. Overheating or contamination: Flush the power steering system. Refer to Power Steering System Filling in this section.

2000 Lincoln Town Car - Steering > Steering System Service > DIAGNOSIS AND TES... Page 4 of 40 9. Check the power steering system for fluid leaks. Check the power steering fluid level. NOTE: It may be necessary to add power steering fluid to achieve the correct level. With the ignition OFF: Wipe off the power steering pump, power steering pressure hose, power steering return hose, power steering fluid cooler, hose assembly and steering gear. CAUTION CAUTION: Do not hold the steering wheel at the stops for an extended amount of time. Damage to the power steering pump can occur. Start the engine and turn the steering wheel from stop-to-stop several times and check for leaks. 10. Inspect the power steering pressure and return hoses, fittings and O-rings for leaks. If a leak is detected at a power steering pressure or return hose, install a new hose. Refer to Power Steering. If a leak is detected between a fitting nut, seal the fitting nut using Teflon joint seal. If a leak is detected at a fitting, tighten to specification. If leak is still evident, visually inspect the fittings, O-rings, and Teflon seals. Install new as necessary. Refer to Power Steering. If a leak is detected at the power steering reservoir, install a new reservoir. Refer to Power Steering. If a leak is detected at a constant tension spring clamp, verify that the hose is fully installed on the fitting and that the hose clamp is correctly positioned. If the leak remains, install a new screw clamp. If a leak is detected at a screw clamp joint, tighten the screw clamp. If the leak remains, inspect the tube end and install a new hose. Refer to Power Steering. If a leak is detected at the power steering pump, install a new power steering pump. Refer to Power Steering. 1 Inspect the power steering gear for leaks. If a leak is detected at the power steering gear, install a new power steering gear. Refer to Power Steering. External Leak Check Potential Power Steering Gear Box Leak Points

2000 Lincoln Town Car - Steering > Steering System Service > DIAGNOSIS AND TES... Page 5 of 40 Click to Enlarge 12. If an obvious cause for an observed or reported concern is found, correct the cause (if possible) before proceeding to the next step. 13. If the cause is not visually evident, verify the symptom and GO to Symptom Chart. Steering System Symptom Definitions Drift/Pull Pull is desribed as a tugging sensation, felt by the hands on the steering wheel, that must be overcome to keep the vehicle going straight. Drift describes what a vehicle with this condition does with the hands off the steering wheel. A vehicle-related drift/pull, on a flat road, can cause a consistent deviation from the straight-ahead path and require constant steering input in the opposite direction to counteract the effect. Drift/pull can be induced by conditions external to the vehicle (i.e., wind, road camber). Excessive Steering Wheel Play Excessive steering wheel play is a condition in which there is too much steering wheel movement before the wheels move. A small amount of steering wheel free play is considered normal. Feedback Feedback is a roughness felt in the steering wheel when the vehicle is driven over rough pavement. Hard Steering or Lack of Assist Hard steering or lack of assist is experienced when the steering wheel effort exceeds specifications. Hard steering can remain constant through the full turn or occur near the end of a turn. It is important to know the difference between hard steering/lack of assist and binding.

2000 Lincoln Town Car - Steering > Steering System Service > DIAGNOSIS AND TES... Page 6 of 40 Hard steering or lack of assist can result from either hydraulic or mechanical conditions. It is extremely important to know if this concern occurs during driving or during high-effort parking maneuvers. Nibble Sometimes confused with shimmy, nibble is a condition resulting from tire interaction with various road surfaces and observed by the driver as small rotational oscillations of the steering wheel. Poor Returnability/Sticky Steering Poor returnability and sticky steering is used to describe the poor return of the steering wheel to center after a turn, or the steering correction, is completed. Shimmy Shimmy, as observed by the driver, is large, consistent, rotational oscillations of the steering wheel resulting from large, sideto-side (lateral) tire/wheel movements. Shimmy is usually experienced near 64 km/h (40 mph), and can begin or be amplified when the tire contacts pot holes or irregularities in the road surface. Wander Wander is the tendency of the vehicle to require frequent, random left and right steering wheel corrections to maintain a straight path down a level road. Diagnostic Trouble Code (DTC) Index NOTE: If rear air suspension control module C251 is disconnected before rear air suspension control module C250, DTCs B1830, C1770, C1790, and C1795 will be retrieved and must be cleared before an accurate list of continuous DTCs can be retrieved. The DTCs C1441 and C1442 will only be retrieved when running the VAPS functional test on the scan tool. The DTC C1897 will only be retrieved once per ignition switch cycle. Diagnostic Trouble Code (DTC) Index DTCs DTC Caused By B1317 B1318 B1342 C1441 C1442 C1722 C1723 C1760 C1763 C1765 Description Battery Voltage High Battery Voltage Low ECU Is Defective Steering Sensor Channel A Circuit Failure Steering Sensor Channel B Circuit Failure Air Height Sensor Power Circuit Short to Power Air Height Sensor Power Circuit Short to Ground Air Rear Height Sensor High Signal Circuit Failure Air Rear Height Sensor High Signal Circuit Short to Ground Action REFER to Vehicle Dynamic. REFER to Vehicle Dynamic. REPLACE the rear air suspension control module. REFER to Vehicle Dynamic. TEST the system for normal operation. Go To Pinpoint Test B. Go To Pinpoint Test B. REFER to Vehicle Dynamic. REFER to Vehicle Dynamic. REFER to Vehicle Dynamic. REFER to Vehicle Dynamic. REFER to Vehicle Dynamic.

2000 Lincoln Town Car - Steering > Steering System Service > DIAGNOSIS AND TES... Page 7 of 40 DTCs DTC Caused By C1768 C1770 C1773 C1790 C1793 C1795 C1798 C1813 C1818 C1830 C1832 C1840 C1842 C1897 U1041 ABS Description Air Rear Height Sensor Low Signal Circuit Failure Air Rear Height Sensor Low Signal Circuit Short to Ground Air Vent Solenoid Output Circuit Failure Air Vent Solenoid Output Circuit Short to Ground Air LR Air Spring Solenoid Output Circuit Failure Air LR Air Spring Solenoid Output Circuit Short to Ground Air RR Air Spring Solenoid Output Circuit Failure Air RR Air Spring Solenoid Output Circuit Short to Ground Air Vent Request Exceeded Maximum Timing Air Air Compressor Request Exceeded Maximum Timing Air Compressor Relay Circuit Failure Air Compressor Relay Circuit Short to Power Air Switch Circuit Failure Air Circuit Short to Power Steering VAPS Circuit Loop Failure SPC Invalid Or Missing Data for Vehicle Speed Action REFER to Vehicle Dynamic. REFER to Vehicle Dynamic. REFER to Vehicle Dynamic. REFER to Vehicle Dynamic. REFER to Vehicle Dynamic. REFER to Vehicle Dynamic. REFER to Vehicle Dynamic. REFER to Vehicle Dynamic. REFER to Vehicle Dynamic. REFER to Vehicle Dynamic. REFER to Vehicle Dynamic. REFER to Vehicle Dynamic. REFER to Vehicle Dynamic. Go To Pinpoint Test C. PERFORM the ABS Self-Test. Parameter Identification (PID) Index Parameter Identification (PID) Index PID Description Expected Values AS_COMP Air Compressor Status

2000 Lincoln Town Car - Steering > Steering System Service > DIAGNOSIS AND TES... Page 8 of 40 PID Description Expected Values OFF---, OFFO--, OFF-B-, OFF--G, OFFO-G, OFFOB-, OFF- BG, OFFOBG, ON---, ONO--, ON-B-, ON--G, ONO-G, ONOB-, ON-BG, ONOBG AS_TRIM Air Accurate Trim TRIM, not TRIM AS_VENT Air Vent Solenoid Status AS_WARN Air Warning Indicator OFF---, OFFO--, OFF-B-, OFF--G, OFFO-G, OFFOB-, OFF- BG, OFFOBG, ON---, ONO--, ON-B-, ON--G, ONO-G, ONOB-, ON-BG, ONOBG ON, OFF ASR_HGT Rear Digital Height Sensor TRIM, HIGH, LOW, HGND, LGND,H_LGND, L_HGND CCNTRAS D_DRRAS Number of Continuous DTCs in Control Module Driver's Door Input to # OF DTCs AJAR, CLOSED FUEL_DR Fuel Door Ajar AJAR, CLOSED IGN_RAS LR_SOL P_DRRAS RR_SOL Ignition RUN/START Input to Rear Air Air LR Air Spring Solenoid Status Passenger Door Ajar Input to Rear Air Air LR Air Spring Solenoid Status ACCY, RUN, START, OFF OFF---, OFFO--, OFF-B-, OFF--G, OFFO-G, OFFOB-, OFF- BG, OFFOBG, ON---, ONO--, ON-B-, ON--G, ONO-G, ONOB-, ON-BG, ONOBG AJAR, CLOSED OFF---, OFFO--, OFF-B-, OFF--O, OFFO-G, OFFOB-, OFF- BG, OFFOBG, ON---, ONO--, ON-B-, ON--G, ONO-G, ONOB-, ON-BG, ONOBG VAPS_IN VAPSII Input Current Loop 100/255 VAPSDRV VAPSII Driver Output State OFF---, OFFO--, OFF-B-, OFF--O, OFFO-G, OFFOB-, OFF- BG, OFFOBG, ON---, ONO--, ON-B-, ON--G, ONO-G, ONOB-, ON-BG, ONOBG VAPSOUT VAPSII Output Current Set Point 100/255 VBATRAS VSS_RAS Battery Voltage Value to Vehicle Speed Input to Active Command Index Active Command Index UDR 0V, OVR 5V, #####volts 1/128 Active Command Display Action Module Sleep COMPRESSR ON, OFF VENT ON, OFF LR SOL ON, OFF RR SOL ON, OFF HGT POWER ON, OFF VAPSII Output Pulse Control VAPSIIOUT 0-100% Symptom Chart Symptom Chart

2000 Lincoln Town Car - Steering > Steering System Service > DIAGNOSIS AND TES... Page 9 of 40 Condition Possible Sources Action No communication with the module rear air suspension control module Fuse. Circuitry. Rear ait suspension control module. Go To Pinpoint Test A. Steering does not vary with vehicle speed Circuitry. Rear air suspension control module. Go To Pinpoint Test D. Low fluid level. Fluid aeration. Steering gear. Power steering pump. Loose or damaged steering linkage. Steering system noise Loose or damaged suspension component (s). Go To Pinpoint Test E. Steering column. Steering column boot bearing. Intermediate shaft. Loose dash boot seal. Steering is very difficult/very easy Seized intermediate shaft U-joints. Damaged, fractured steering column bearing (s). Steering gear. Power steering pump. Power steering hoses. Binding dash boot seal. Go To Pinpoint Test F. Excessive steering wheel play Steering gear. Steering column. Go To Pinpoint Test G. Steering column intermediate shaft. Steering linkage. Ball joints.

Page 10 of 40 Condition Possible Sources Action Strut bearing plate (if applicable). Tire pressure. Wheel alignment. Steering system drift/pull/wander Steering gear. Unevenly loaded vehicle. Steering column intermediate shaft. Go To Pinpoint Test H. Frame alignment. Feedback Loose, worn or damaged tie-rod. GO to Component Tests, Tie-Rod Articulation Torque in this section. Loose, worn or damaged tie-rod ends. GO to Component Tests, Steering Linkage in this section. Loose or damaged steering gear insulators or bolts. INSTALL new steering gear insulators or bolts if necessary, or TIGHTEN the bolts as needed. Loose lower steering column shaft U-joint bolts. INSTALL new bolts or TIGHTEN the bolts. REFER to Steering Column. Loose suspension bushings, fasteners,ball joints, or strut bearing plate (if applicable). INSTALL new components as necessary. REFER to Front. Worn or damaged steering column bearing (s). INSTALL new steering column bearings(s). REFER to Wheels and Tires. Poor returnability/sticky steering Binding lower steering column shaft U-joints. INSTALL a new lower steering column shaft.

Page 11 of 40 Condition Possible Sources Action REFER to Steering Column. Loose, worn or damaged front wheel knuckle tierod. GO to Component Tests, Tie-Rod Articulation Torque in this section. Loose, worn or damaged tie-rod ends. GO to Component Tests, Steering Linkage in this section. components. REFER to System General Information for the suspension diagnoses and testing. Binding steering column bearing(s). Binding dash boot seal. INSTALL new steering column bearings(s). REFER to Steering Column. Shimmy Loose, worn or damaged tie-rod end. GO to Component Tests, Steering Linkage in this section. Loose, worn or damaged tie-rod. GO to Component Tests, Tie-Rod Articulation Torque in this section. components. REFER to System General Information for the suspension diagnosis and testing. Pinpoint Tests PINPOINT TEST A: NO COMMUNICATION WITH THE MODULE REAR AIR SUSPENSION CONTROL MODULE

Page 12 of 40 A1 CHECK THE FUSES Fuse Junction Panel Fuse 8 (10A) 2. Power Distribution Box Fuse 17 (10A) Are fuse junction panel fuse 8 (10A) and power distribution box fuse 17 (10A) OK? GO to A2. REPLACE the fuse in question. TEST the system for normal operation. If the fuse fails again, CHECK for short to ground. REPAIR as necessary. TEST the system for normal operation. A2 CHECK CIRCUIT 296 (W/P) FOR AN OPEN 2. C250

Page 13 of 40 3. 4. 4. Measure the voltage between rear air suspension control module C250-16, circuit 296 (W/P), and ground. Is the voltage greater than 10 volts? GO to A3. REPAIR circuit 296 (W/P). TEST the system for normal operation. A3 CHECK CIRCUIT 418 (DG/Y) FOR AN OPEN Measure the voltage between rear air suspension control module C250-1, circuit 418 (DG/Y), and ground. Is the voltage greater than 10 volts? GO to A4.

Page 14 of 40 REPAIR circuit 418 (DG/Y). TEST the system for normal operation. A4 CHECK CIRCUIT 57 (BK) FOR AN OPEN 2. 2. Measure the resistance between rear air suspension control module C250-6, circuit 57 (BK), and ground. Is the resistance less than 5 ohms? REFER to Module Communications Network. REPAIR circuit 57 (BK). TEST the system for normal operation. PINPOINT TEST B: DTC C1441, C1442 STEERING SENSOR CIRCUIT FAILURE B1 CHECK FUSE JUNCTION PANEL FUSE 8 (10A) 2.

Page 15 of 40 Fuse Junction Panel Fuse 8 (10A) Is the fuse OK? GO to B2. REPLACE the fuse. TEST the system for normal operation. If the fuse fails again, CHECK for short to ground. REPAIR as necessary. TEST the system for normal operation. B2 CHECK STEERING WHEEL ROTATION SENSOR SIGNAL CIRCUIT 633 (R) AT THE REAR AIR SUSPENSION CONTROL MODULE C250 2. 3. Place the 73III Automotive Meter in the diode check position. 4. 4. NOTE: Touch 73III Automotive Meter leads together to be sure the audio (beep) function is operational. NOTE: The 73III Automotive Meter should beep several times while rotating the steering wheel. Connect 73III Automotive Meter leads between rear air suspension control module C250-18, circuit 633 (R), and ground, and listen for an audible beep while turning the steering wheel one quarter turn in each direction.

Page 16 of 40 Does 73III Automotive Meter beep multiple times in both directions? GO to B3. GO to B4. B3 CHECK STEERING WHEEL ROTATION SENSOR SIGNAL CIRCUIT 644 (BR) AT THE REAR AIR SUSPENSION CONTROL MODULE With 73III Automotive Meter in the diode check position, connect 73III Automotive Meter leads between rear air suspension control module C250-19, circuit 634 (BR), and ground, and listen for an audible beep while turning the steering wheel one quarter turn in each direction. Does 73III Automotive Meter beep multiple times in both directions? REPLACE the rear air suspension control module. REFER to Vehicle Dynamic. TEST the system for normal operation. GO to B9. B4 CHECK STEERING WHEEL ROTATION SENSOR C184 FOR POWER AND GROUND

Page 17 of 40 2. Steering Wheel Rotation Sensor C2001 3. 4. 4. Measure the voltage between steering wheel rotation sensor C2001-1, circuit 57 (BK), and steering wheel rotation sensor C2001-4, circuit 296 (W/P). Is the voltage greater than 10 volts? GO to B6. GO to B5. B5 CHECK FOR POWER TO THE STEERING WHEEL ROTATION SENSOR Measure the voltage between steering wheel rotation sensor C2001-4, circuit 296 (R), and ground.

Page 18 of 40 Is the voltage greater than 10 volts? REPAIR circuit 57 (BK). TEST the system for normal operation. REPAIR circuit 296 (W/P). TEST the system for normal operation. B6 CHECK CIRCUIT 633 (R) FOR SHORT TO POWER Measure the voltage between steering wheel rotation sensor C2001-3, circuit 633 ( R), and ground. Is voltage present? REPAIR circuit 633 ( R). TEST the system for normal operation. GO to B7. B7 CHECK CIRCUIT 633 (R) FOR SHORT TO GROUND Measure the resistance between steering wheel rotation sensor C2001-3, circuit 633 ( R), and ground.

Page 19 of 40 Is the resistance greater than 10,000 ohms? GO to B8. REPAIR circuit 633 (R). TEST the system for normal operation. B8 CHECK CIRCUIT 633 (R) FOR OPEN Measure the resistance between rear air suspension control module C250-18, circuit 633 (R), and steering wheel rotation sensor C2001-3, circuit 633 (R). Is the resistance less than 5 ohms? REPLACE the steering wheel rotation sensor. REFER to Power Steering. TEST the system for normal operation. REPAIR circuit 633 (R). TEST the system for normal operation. B9 CHECK CIRCUIT 634 (BR) FOR SHORT TO POWER

Page 20 of 40 Measure the voltage between steering wheel rotation sensor C2001-2, circuit 634 (BR), and ground. Is voltage present? REPAIR circuit 634 (BR). TEST the system for normal operation. GO to B10. B10 CHECK CIRCUIT 634 (BR) FOR SHORT TO GROUND Measure the resistance between steering wheel rotation sensor C2001-2, circuit 634 ( BR), and ground. Is the resistance greater than 10,000 ohms? GO to B1 REPAIR circuit 634 (BR). TEST the system for normal operation. B11 CHECK CIRCUIT 634 (BR) FOR OPEN Measure the resistance between rear air suspension control module C250-19, circuit 634 (BR), and steering wheel rotation sensor C2001-2, circuit 634 (BR).

Page 21 of 40 Is the resistance less than 5 ohms? REPLACE the steering wheel rotation sensor. REFER to Power Steering. TEST the system for normal operation. REPAIR circuit 634 (BR). TEST the system for normal operation. PINPOINT TEST C: DTC C1897 STEERING VAPS II CIRCUIT LOOP FAILURE C1 CHECK THE POWER STEERING CONTROL VALVE ACTUATOR 2. Power Steering Control Valve Actuator C184 3. Check the power steering control valve actuator C184 for damaged pigtail, bent pins, dirt, or corrosion. Are the connector and pigtail OK?

Page 22 of 40 GO to C2. REPAIR as necessary. TEST the system for normal operation. C2 CHECK THE POWER STEERING CONTROL VALVE ACTUATOR FOR SHORT TO GROUND Measure the resistance between power steering control valve actuator terminal (component side), and ground. Is the resistance greater than 10,000 ohms? GO to C3. REPLACE the power steering control valve actuator. REFER to Power Steering. TEST the system for normal operation. C3 CHECK THE POWER STEERING CONTROL VALVE ACTUATOR RESISTANCE Measure the resistance between power steering control valve actuator terminals. Is the resistance between 4-8 ohms?

Page 23 of 40 GO to C4. REPLACE the power steering control valve actuator. REFER to Power Steering.TEST the system for normal operation. C4 CHECK CIRCUIT 87 (T/Y) FOR SHORT TO BATTERY 2. C251 3. 3. Measure the voltage between power steering control valve actuator C184, circuit 87 (T/Y), and ground. Is voltage present? REPAIR circuit 87 (T/Y). REPLACE the air suspension module. REFER to Vehicle Dynamic. TEST the system for normal operation. GO to C5. C5 CHECK CIRCUIT 86 (GY/O) FOR SHORT TO BATTERY

Page 24 of 40 Measure the voltage between power steering control valve actuator C184, circuit 86 (GY/O), and ground. Is voltage present? REPAIR circuit 86 (GY/O). TEST the system for normal operation. GO to C6. C6 CHECK CIRCUIT 87 (T/Y) FOR SHORT TO GROUND Measure the resistance between power steering control valve actuator C184, circuit 87 (T/Y), and ground. Is the resistance greater than 10,000 ohms? GO to C7. REPAIR circuit 87 (T/Y). TEST the system for normal operation. C7 CHECK CIRCUIT 86 (GY/O) FOR SHORT TO GROUND

Page 25 of 40 Measure the resistance between power steering control valve actuator C184, circuit 86 (GY/O), and ground. Is the resistance greater than 10,000 ohms? GO to C8. REPAIR circuit 86 (GY/O). TEST the system for normal operation. C8 CHECK CIRCUIT 87 (T/Y) FOR AN OPEN Measure the resistance between power steering control valve actuator C184, circuit 87 (T/Y), and rear air suspension control module C251-26, circuit 87 (T/Y). Is the resistance less than 5 ohms? GO to C9. REPAIR circuit 87 (T/Y). TEST the system for normal operation. C9 CHECK CIRCUIT 86 (GY/O) FOR AN OPEN Measure the resistance between power steering control valve actuator C184, circuit 86 (GY/O), and rear air suspension control module C251-14, circuit 86 (GY/O).

Page 26 of 40 Is the resistance less than 5 ohms? REPLACE the rear air suspension control module. REFER to Vehicle Dynamic. TEST the system for normal operation. REPAIR circuit 86 (GY/O). TEST the system for normal operation. PINPOINT TEST D: STEERING DOES NOT VARY WITH VEHICLE SPEED D1 CHECK THE SPEEDOMETER 2. Check the speedometer by driving the vehicle and observing the speedometer operation. Does the speedometer operate properly? GO to D2. REFER to Instrument Cluster. D2 CHECK FOR DTC U1041

Page 27 of 40 2. Scan Tool 3. 4. 4. Retrieve and document DTCs. Is DTC U1041 retrieved? REFER to Anti-Lock Control Traction Control. If any DTCs are retrieved, GO to the Diagnostic Trouble Code (DTC) Index. If no DTCs are retrieved, REPLACE the rear air suspension control module. REFER to Vehicle Dynamic. TEST the system for normal operation. PINPOINT TEST E: STEERING SYSTEM NOISE E1 CHECK FOR MECHANICAL NOISE Test drive the vehicle to verify the steering system noise. Does the steering system make a clunk noise?

Page 28 of 40 CHECK for loose, worn or damaged tie rod ends. REFER to Component Tests, Steering Linkage in this section. CHECK for loose or worn steering gear isolators (if applicable). INSTALL new isolators if necessary. REFER to Power Steering. If the noise is from the steering column, CHECK the steering column intermediate shaft for grounding through the body and repair as necessary. If the noise is from the steering column boot bearing, INSTALL a new steering column boot bearing. REFER to Steering Column. If the noise is from the suspension components, INSTALL new suspension components as necessary. REFER to Front. If the noise is from loose, worn or damaged intermediate shaft U-joint(s), INSTALL a new lower steering column shaft. REFER to Steering Column. If a squeak is present in the steering column, REPAIR the steering column mountings or align the steering column as necessary. REFER to Steering Column. For all other concerns, GO to E2. E2 VERIFY THE CONCERN NOTE: Make sure that the vehicle is on a flat dry surface, the transmission is in PARK, and that the windows are rolled up. NOTE: Some power steering noise is expected. If in doubt of the acceptability of the noise level, evaluate another vehicle of the same model and powertrain. 2. Turn the steering wheel one-half turn off-center to the right then one-half turn offcenter to the left. Is the power steering noisy? If a grunt noise is present, verify the steering column boot is OK and the exhaust system is not grounding out. If a moan is present, verify that the tie rod ends and ball joints are OK. GO to E3. If a squeal is present, INSPECT and INSTALL a new engine drive belt or belt tensioner as necessary. REFER to Engine System General Information. If the steering system noise is a hiss or whistle, INSPECT the steering column boot at the dash panel. REPAIR or INSTALL a new boot as necessary. REFER to Steering Column. INSPECT the steering gear input shaft and valve for wear or damage. REFER to Power Steering.

Page 29 of 40 INSPECT the power steering gear, intermediate shaft and power steering lines and hoses for grounding to the body and repair as necessary. INSPECT for openings or missing plugs in the instrument panel cowl and repair as necessary. If there are no missing plugs or openings in the cowl, grounded power steering gear, intermediate shaft or power steering lines or hoses, GO to E6. E3 CHECK FOR COLD START NOISE NOTE: Some noise during an extremely cold start -25.5 C (-14 F) is normal and should improve as the steering system warms up (usually within 60 seconds). 2. Verify the noise condition. Is the noise present only during cold start up? CHECK for contamination in the power steering reservoir screen. FLUSH the power steering system as necessary. REFER to Power Steering System Flushing in this section. TEST the system for normal operation. GO to E4. E4 INSPECT THE POWER STEERING FLUID 2. With the engine OFF, inspect the power steering fluid for aeration. Is the power steering fluid foamy or aerated? GO to E5. PURGE the power steering system. REFER to Power Steering System Purging in this section. If a whine or a moan is still present, INSTALL a new power steering pump. REFER to Power Steering.

Page 30 of 40 If a grunt is still present, INSTALL a new power steering gear. REFER to Power Steering. E5 CHECK THE POWER STEERING FLUID LEVEL WITH THE ENGINE ON AND OFF NOTE: Record the vacuum level when the pump noise occurs with no steering input. Vacuum level should be greater than 10 inches of mercury with CII pump and 15 inches of mercury on the CIII pump. 2. With the engine running, inspect the power steering fluid level. 3. 4. With the engine off, inspect the power steering fluid level. Does the power steering fluid level change with the engine off? PURGE the power steering system. REFER to Power Steering System Purging in this section. GO to E6. E6 CHECK THE POWER STEERING PUMP NOTE: Do not turn the steering wheel to either the right or left stop. Power steering relief noise will occur and is normal at the stop positions. 2. With the engine running, rotate the steering wheel 90 degrees to the left then to the right.

Page 31 of 40 Does the frequency of the hiss change between the left and right positions? INSTALL a new power steering gear. REFER to Power Steering. INSTALL a new power steering pump. REFER to Power Steering. PINPOINT TEST F: STEERING IS VERY DIFFICULT/VERY EASY F1 CHECK THE STEERING COLUMN BEARINGS AND THE INTERMEDIATE SHAFT NOTE: Be sure to keep the clockspring centered when disconnecting the intermediate shaft. Refer to Supplemental Restraint System. Check the steering column and intermediate shaft for grounding. 2. Disconnect the steering column intermediate shaft at the steering column. 3. Verify that the intermediate shaft universal joints do not bind and move freely and that the steering column bearing rotates freely. Are the steering column bearing and intermediate shaft universal joints OK? GO to F2. If the steering column or the intermediate shaft are grounding, repair as necessary. If the steering column bearings or the intermediate shaft are binding. INSTALL a new intermediate shaft or steering column. REFER to Steering Column. F2 CHECK THE FRONT BALL JOINTS Check that the front ball joints move freely and are not binding or sticking. Refer to System General Information. Are the front ball joints OK? GO to F3. INSTALL new ball joints as necessary. REFER to Front. F3 MONITOR ENGINE rpm CHANGES NOTE: Make sure that the vehicle is on a flat dry surface.

Page 32 of 40 2. CAUTION CAUTION: Do not hold the steering wheel at the stops for an extended amount of time. Damage to the power steering pump can occur. Turn the steering wheel once to the left stop position and then to the right stop position. 3. Note the engine rpm during the turns. Does the engine rpm change when turning the steering wheel? If no power steering assist is present and the engine rpm changes, INSTALL a new steering gear. REFER to Power Steering. If left-to-right variation is present, INSTALL a new steering gear. REFER to Power Steering. If no power steering assist is present and the engine rpm does not change, INSTALL a new power steering pump. REFER to Power Steering. If excessive effort is required in one or both directions, INSTALL a new power steering pump. REFER to Power Steering. CARRY OUT the Pump Flow and Pressure Test. REFER to Component Tests in this section. PINPOINT TEST G: EXCESSIVE STEERING WHEEL PLAY G1 CHECK THE STEERING COLUMN BEARING Inspect the steering column mounting fasteners and bearing for looseness. Are the fasteners and bearing OK? GO to G2. TIGHTEN the steering column mounting fasteners or INSTALL a new steering column. REFER to Steering Column. G2 CHECK THE STEERING LINKAGE FOR LOOSENESS

Page 33 of 40 Carry out the Steering Linkage component test. Refer to Component Tests in this section. Is the steering linkage OK? REFER to System General Information to diagnose the suspension components. INSTALL new steering linkage as necessary. REFER to Steering Linkage. PINPOINT TEST H: STEERING SYSTEM DRIFT/PULL/WANDER H1 CHECK FOR TIRE PULL Rotate the front wheel and tire assemblies side-to-side. Refer to Wheels and Tires. 2. Carry out a road test on a smooth, flat road. Does the vehicle drift/pull? If vehicle pulls in the opposite direction, GO to H2. If vehicle pulls in original direction, GO to H3. Concern has been corrected. H2 ROTATE THE WHEEL AND TIRE ASSEMBLIES FRONT TO REAR Rotate the front wheel and tire assemblies front to rear. Refer to Wheels and Tires. 2. Carry out a road test on a smooth, flat road. Does the vehicle drift/pull? GO to H3. Concern has been corrected. H3 CHECK THE STEERING COLUMN INTERMEDIATE SHAFT NOTE: Be sure to keep the clockspring centered when disconnecting the intermediate shaft. Refer to Supplemental Restraint System. Check the steering column and intermediate shaft for grounding.

Page 34 of 40 2. Disconnect the steering column intermediate shaft at the steering column. 3. Inspect the steering column intermediate shaft U-joints for looseness or wear. Are the steering column intermediate shaft universal joints OK? GO to H4. INSTALL a new steering column intermediate shaft. REFER to Steering Column. H4 CHECK THE STEERING GEAR MOUNTING Check the steering gear mounts for looseness or wear. Are the steering gear mounts OK? GO to H5. INSTALL new steering gear mounts. REFER to Power Steering. H5 CHECK THE STEERING GEAR Carry out the Steering Gear Valve component test in this section. Is the steering gear valve OK? GO to H6. REPAIR or INSTALL a new steering gear. REFER to Power Steering. H6 CHECK THE SUSPENSION COMPONENTS CHECK for loose or worn suspension components. REFER to Front or Rear. Are the suspension components OK? GO to H7. INSTALL new suspension components. REFER to Front or Rear. H7 CHECK THE WHEEL ALIGNMENT NOTE: The vehicle will tend to pull toward the side with the least positive caster and the most positive camber.

Page 35 of 40 Using a suitable alignment system, measure the wheel alignment settings. Refer to System General Information. Are the alignment settings within specifications? CHECK for correct frame alignments. REFER to Front End Body Panels. ADJUST the alignment angles to specifications. DO NOT exceed specifications. TEST the system for normal operation. Component Tests Steering Linkage NOTE: Excessive vertical motion of the studs relative to the sockets may indicate excessive wear. With the vehicle on the ground and the parking brake applied, start the vehicle and carry out the following: Have an assistant rotate the steering wheel back and forth 360 degrees and watch for relative motion of the studs in the steering linkage ball sockets. Watch for loose steering gear mounting. 2. An additional check is with the KOEO and the front wheels raised off the ground, grasp the wheel at the front and rear and watch for excessive play or binding in the joints while trying to steer the wheels. 3. NOTE: Improper separation of the tapered stud from its seat will cause premature failure of the ball socket. Steel greaseable joints can be checked for excessive wear by measuring the torque it takes to turn the stud. Separate the tapered stud from its seat and thread the attaching nut back onto the stud. Turn the stud with an inch-pound torque wrench and note the torque required to turn the stud. Torque Required to Turn Stud in Socket Nm Lb-In New steel joints 2.0-5.3 17.8-47.3 Used steel joints 0.5-3.0 5.0-26.5 Steel joints with excessive play 0.0-0.5 0.0-5.0 NOTE: Some joint turning torques will be as little as 0.5 Nm (5.0 lb-in) within the first 1,600 km (1,000 miles) and will remain there for the life of the joint. Only replace a joint that requires less than 0.5 Nm (5.0 lb-in) of turning torque. 4. Install new components if necessary. Tighten any worn, damaged, or loose components.

Page 36 of 40 Turning Effort Test NOTE: Make sure that the front wheels are correctly aligned and the tire pressure is correct before checking the steering effort. Park the vehicle on dry concrete and set the parking brake. 2. Insert a thermometer into the power steering oil reservoir. 3. CAUTION CAUTION: Do not hold the steering wheel against the stops for more than 3 to 5 seconds at a time. Damage to the power steering pump can occur. Idle the engine for 2 to 3 minutes. Turn the steering wheel from stopto-stop several times to warm the fluid to 50-60 C (122-140 F). 4. With the engine running, attach the spring scale to the rim of the steering wheel. 5. Measure the pull required to turn the steering wheel one complete revolution in each direction. Refer to Steering Wheel Turning Effort under General Specifications in this section. Sector Shaft Arm Inspection Backlash WARNING WARNING: The electrical power to the air suspension must be shut off prior to hoisting jacking or towing an air suspension vehicle. This can be accomplished by turning off the air suspension switch located in the luggage compartment. Failure to do so can result in unexpected inflation or deflation of the air springs, which can result in the shifting of the vehicle during these operations. Raise and support the vehicle. For additional information, refer to Jacking and Lifting. 2. Inspect the sector shaft air dust boot for cuts or tears. If it is cut or torn, install a new sector shaft arm. For additional information, refer to Front.

Page 37 of 40 3. Pull downward on the sector shaft arm drag link. 4. Using digital calipers, measure the distance from the top of the sector shaft arm forging to the bottom of the drag link. 5. Using a C-clamp, fully compress the sector shaft arm ball stud.

Page 38 of 40 6. Measure the distance from the top of the sector shaft arm forging to the bottom of the drag link. 7. Substract the second measurement from the first measurement. If the movement measure is greater than 0.11 in., install a new sector shaft arm. For additional information, refer to Power Steering. Pump Flow and Pressure Test WARNING WARNING: Do not touch the flowmeter during the test procedure, or severe burns and serious injury can occur. Failure to follow these instructions may result in personal injury. CAUTION CAUTION: Make sure that the connection point will not interfere with any of the engine accessory drive components or drive belts. Install the power steering analyzer at the high pressure port of the power steering pump. Make sure the power steering analyzer gate valve is fully open. 2. Place a dial thermometer in the power steering pump reservoir. 3. Check the power steering fluid level. If necessary, add specified power steering fluid. 4. Install a digital tachometer. 5. CAUTION CAUTION: Do not hold the steering wheel against the stops for more than 3 to 5 seconds at a time. Damage to the power steering pump can occur. Start the engine. Place the transmission in NEUTRAL. Set the parking brake. Raise the power steering fluid temperature to 74-80 C (165-175 F) by rotating the steering wheel fully to the left and right several times. 6. With the steering wheel in the straight-ahead position, set the engine speed to 2,100 rpm. Record the flow rate and pressure readings. If the flow rate is below the flow rate specification, continue with the test procedure. If the pressure reading is above the maximum pressure specification, check the power steering hoses for kinks and restrictions. 7. Partially close the gate valve to obtain 750 psi. Set the engine speed at idle. Record the flow rate.

Page 39 of 40 8. If the flow is less than the specified flow rate, install a new power steering pump. CAUTION CAUTION: Do not allow the gate valve to remain closed for more than 5 seconds. Completely close and partially open the gate valve 3 times. Record the pressure relief valve actuation pressure reading. If the pressure does not meet the relief pressure specification, then install a new power steering pump. 9. Set engine speed to 2,100 rpm. Record the flow rate. 10. If the flow rate varies more than 3.785 liters/minute (1 gallon/minute) from the initial flow rate reading, install a new power steering pump. CAUTION CAUTION: Do not hold the steering wheel against the stops for more than 3 to 5 seconds at a time. Damage to the power steering pump can occur. Set the engine speed at idle. Turn (or have an assistant turn) the steering wheel to the left and right stops. Record flow rate and pressure readings at the stops. The pressure reading at both stops should be nearly the same as the maximum pump relief pressure. The flow rate should drop below 9 liters/minute (0.5 gallons/minute). If the pressure does not reach the maximum pump relief pressure or the flow rate does not drop below the specified value, excessive internal leakage is occurring. Install a new steering gear as necessary. Refer to Power Steering. 1 Turn (or have an assistant turn) the steering wheel slightly in both directions and release quickly while watching the pressure gauge. The pressure reading should move from the normal back pressure reading and snap back as the steering wheel is released. If the pressure returns slowly or sticks, the rotary valve in the steering gear is sticking or the steering column is binding. Check the steering column and linkages before repairing the steering gear. Tie-Rod Articulation Torque NOTE: This check may be done with the steering gear on or off the vehicle. Disconnect the tie-rod-end from the front wheel knuckle. Refer to Power Steering. 2. Move the front wheel knuckle tie-rod back and forth three times.

Page 40 of 40 3. Hook a spring scale over the tie-rod end, or the threaded portion of the front wheel knuckle tie-rod, and measure the force required to move the front wheel knuckle tie-rod. Refer to General Specifications, Tie-Rod Articulation Torque in this section. 4. If the force required to move the front wheel knuckle tie-rod does not meet the specifications, install a new front wheel knuckle tie-rod. Refer to Power Steering. Steering Gear Valve With the vehicle in motion, place the transmission in NEUTRAL and turn the engine OFF. If the vehicle does not pull with the engine OFF, repair or install a new steering gear. Refer to Power Steering. 2. If the vehicle pulls with the engine OFF, switch the right side front wheel to the left side of the vehicle and the left side front wheel to the right side of the vehicle. 3. If the vehicle pulls to the opposite side, switch the front wheels with the rear wheels keeping them on the same side of the vehicle. 4. If the vehicle pull direction does not change, check the front suspension components, wheel alignment and frame alignment. Refer to System General Information or an appropriate frame dimensions manual.