2006 Expedition/Navigator Workshop Manual

Transcription

1 Page 1 of 19 SECTION : Vehicle Dynamic Suspension DIAGNOSIS AND TESTING Procedure revision date: 10/06/2009 Vehicle Dynamic Suspension 4-Wheel Air Suspension Printable View (214 KB) Refer to Wiring Diagrams Cell 41, Programmable Ride Control for schematic and connector information. Special Tool(s) Worldwide Diagnostic System (WDS) Vehicle Communication Module (VCM) with appropriate adapters, or equivalent diagnostic tool Vacuum Tester or equivalent 014-R Digital Multimeter or equivalent 105-R0051 Flex Probe Kit 418-F090 (105-R025B) Principles of Operation The air suspension (vehicle dynamics) module (VDM) commands changes in vehicle height that are necessary for both the load leveling and the vertical height adjustment features. The load leveling feature automatically makes adjustments in vehicle height so that the vehicle is always at target height and that constant front-to-rear vehicle attitudes are maintained over the load range of the vehicle. Adjustments in height that are necessary to correct height differences between the vehicle left and right sides for the system are restricted to what can be reliably achieved with 3 height sensors. The height adjustment feature has 3 vehicle target heights within a 51 mm (2 in) span: Kneel height improves the ease of entering and exiting by lowering the vehicle 25 mm (0.98 in) below the trim height in the front and rear when the vehicle ignition is in the OFF or LOCK positions and the vehicle is stationary and all doors, liftgate and liftgate glass are CLOSED. Trim height normal vehicle ride position; vehicle adjusts to trim position when the ignition is ON, when the transmission is initially shifted to DRIVE or REVERSE mode, when all doors and the liftgate are CLOSED or when speed of more than 24 km/h (15 mph) is detected. Off-road height improves ground clearance by raising the vehicle 25 mm (0.98 in) above trim height in the front and rear when the vehicle is at 4x4 low modes and the vehicle speed is less than 30 km/h (19 mph). The VDM uses the controller area network (CAN) communications network for sending and receiving various information. For additional information about CAN, refer to Section The 4-wheel air suspension (4WAS) system holds vehicle height when any door or rear liftgate is opened. The system stores front and rear vehicle height the moment any door is detected OPEN. The system then maintains this height regardless of the addition or removal of a load. The system returns to its commanded height when all doors are CLOSED or vehicle speed exceeds 24 km/h (15 mph). The system will remain active for 40 minutes after the ignition is turned OFF to make limited height adjustments as necessary. Vehicle Height Modes Ignition State Transfer Case Mode Speed or Speed Range Resulting Vehicle Height OFF 4x2, A4WD, 4x4 HI N/A Kneel (TRIM - 25 mm) ON and RUN 4x2, A4WD, 4x4 HI All speeds TRIM ON and RUN 4x4 Low Below 30 km/h (19 mph) Off-Road (TRIM + 25 mm) ON and RUN 4x4 Low Above 40 km/h (25 mph) TRIM OFF 4x4 Low N/A Stays at current position (prior to ignition transition) Air Suspension Service Switch The air suspension service switch signal is needed to turn on the VDM. Without the VDM receiving this signal, the 4WAS system is inoperative at speeds below 24 km/h (15 mph) and will not react when the vehicle is raised or lowered. At speeds above 24 km/h (15 mph), the system will vent as if the air suspension service switch is in the ON position. Vehicles Without Message Center When the air suspension service switch is in the OFF position and the ignition switch is in the RUN position, CHECK SUSP will appear in the RH corner of the instrument cluster. Vehicles With Message Center When the air suspension service switch is in the OFF position and the ignition switch is in the RUN position, the message center will display SUSPENSION SWITCHED OFF.

2 Page 2 of 19 Air Compressor The air compressor: consists of the compressor and vent solenoid; neither are serviced as individual items. is a single cylinder electric motor driven unit that provides pressurized air as required. is powered by an electromechanical relay, which is controlled by the VDM. passes pressurized air through the compressor air drier that contains silica gel (a drying agent). Moisture is then removed from the compressor air drier when vented air passes out of the system during vent operation. has a single port drier that can be serviced separately. The vent solenoid: allows air to escape from the system during venting actions. is part of the air compressor cylinder head. shares a common electrical connector with the air compressor motor. is enclosed in the cylinder head casting, which forms an integral valve housing that allows the valve tip to enter the pressurized side of the system. has an O-ring seal that prevents air leakage past the valve tip. opens when the VDM determines that lowering is required. provides an escape route for pressurized air when system pressures exceed safe operating levels. has a 1,034 kpa (150 psi) internal relief valve. is installed with the air compressor as a unit. Air Spring The 4WAS system has front and rear air springs. The air springs provide a varying spring rate proportional to the system's air pressure and volume. The air suspension system regulates the air pressure in each air spring by compressing and venting the system's air. Increasing air pressure (compressing) raises the vehicle; decreasing air pressure (venting) lowers the vehicle. Vehicle height is maintained by the addition and removal of air in each air spring through an air spring solenoid installed in the upper spring cap and energized through the VDM module. Air Lines and Fittings NOTE: Apply a soapy water solution to the air lines to verify the location of air leaks. If the air lines are cut, ruptured or leaking, a service repair kit is available. Nylon air lines with quick connect fittings connect to the air compressor and air spring solenoids. The compressor assembly output line is divided by the use of a fitting to supply the front and rear air springs. Fittings are also used to divide the air supply to the RH and LH air spring solenoids. Air Suspension Height Sensors There are 2 sensors used for the front suspension and 1 sensor used for the rear suspension. The sensors send a voltage signal to the VDM. The output ranges from approximately 4.5 volts at minimum height (when the vehicle is low or in full jounce) to 0.5 volt at maximum height (when the vehicle is high or in full rebound). The sensors have a usable range of ± 45 degrees compared to total suspension travel of 196 mm (7.84 in) at the front wheels and 240 mm (9.6 in) at the rear wheels. Therefore, the sensors are mounted to the suspension at a point where full suspension travel at the wheel is relative to the travel at the height sensor. The front height sensors are mounted to the frame and the links are attached to the upper arm ball studs. The left and right sensors have opposite polarity and are not interchangeable. The rear height sensor is mounted to the frame and the link is attached to the rear lower arm ball stud. When the height sensor indicates that the vehicle is lower than trim under normal driving conditions, the air compressor will turn ON and pump compressed air to the system. When the sensor indicates that the vehicle is raised above trim under normal driving conditions, this will cause the air to be vented from the system to lower the vehicle to its trim height level. Compressor Relay An electromechanical relay is used in the air suspension system for compressor control. The relay switches high current loads in response to low power signals and is controlled by the logic of the VDM. The compressor relay is energized by the VDM to have high current flow from the battery to the compressor motor. Vehicle Dynamic Module (VDM) NOTE: The VDM must receive a ride height adjustment calibration and must pass a pneumatic test when it is installed new or swapped. The vehicle dynamic module (VDM) controls the air compressor motor through an electromechanical relay, all air spring solenoids and provides power to front and rear height sensors. The VDM also controls vehicle height adjustments by monitoring the 3 height sensors and other CAN messages. The VDM conducts all fail-safe and diagnostic strategies and contains self-test and communication software for testing the vehicle and related components. The VDM monitors and controls the air suspension system through a 26-pin, 2-way connector. The VDM is keyed so that it cannot be plugged into an incorrect harness. There are 2 harness electrical connectors and each is uniquely colored and keyed to prevent reversed connections. Air Spring Solenoid WARNING: Never rotate an air spring solenoid valve to the release slot in the end cap fitting until all pressurized air has escaped from the spring to prevent damage or injury. The air spring solenoid: allows air to enter and exit the air spring during leveling operations. is electrically operated and controlled by the VDM. is serviced separately from the air spring. Inspection and Verification 1. Verify the customer concern. 2. NOTE: If the door ajar indicator is illuminated when all doors, the liftgate and the liftgate glass are closed, the air suspension will not work correctly. Repair the door ajar indicator. Refer to Section Visually inspect for obvious signs of mechanical and electrical damage.

3 Page 3 of 19 Visual Inspection Chart Mechanical Restricted suspension movement Excessive vehicle load Damaged air line(s) Unmounted height sensor(s) Damaged front air spring(s) Damaged rear air spring(s) Damaged solenoid valve(s)/height sensor(s) Electrical Central junction box (CJB) fuses: 30 (25A) 27 (5A) 111 (50A) Circuitry Loose, corroded or disconnected electrical connectors Air suspension service switch is in the OFF position 3. If an obvious cause for an observed or reported concern is found, correct the cause (if possible) before proceeding to the next step. 4. NOTE: The VDM is also referred to as the 4-wheel air suspension (4WAS) module. If the cause is not visually evident, connect the diagnostic tool to the data link connector (DLC) to retrieve continuous diagnostic trouble codes (DTCs) and to execute On-Demand Self Test diagnostics for the VDM. If the On-Demand Self Test is passed and no DTCs are retrieved, GO to Symptom Chart to continue diagnostics. If DTCs are retrieved, GO to the VDM Diagnostic Trouble Code (DTC) Index in this section. If the VDM cannot be accessed by the diagnostic tool, GO to Pinpoint Test A. Pneumatic Test This test verifies that the air lines are connected and that they are not restricted. It also verifies that the air compressor, air compressor vent solenoid and air spring solenoid valves are functioning correctly. Verify that the following conditions are met before running the Pneumatic Test. All doors, the liftgate and the liftgate glass must be CLOSED. Vehicle in PARK. The vehicle speed is less the 10 km/h (6 mph). The air suspension service switch must be in the ON position. Test is used to clear DTCs C1990 and C1991. Trim Height Test (or Accurate Trim Test) NOTE: The trim height test is used to verify trim height only. If trim height needs to be adjusted, refer to Ride Height Adjustments in this section. The trim height test is used to make the vehicle level to within 2 mm (0.08 in) of the calibrated trim height. Accurate trim test should be run before setting vehicle alignment. The following conditions must be met for the trim height test to run: All doors, the liftgate and the liftgate glass must be CLOSED. The transmission is in PARK. The vehicle speed is less than 10 km/h (6 mph). The ignition switch is in the ON position. The air suspension service switch is in the ON position. Battery voltage is greater than 11 volts for the duration of the test. 1. Fulfill the pre-conditions. 2. Install a battery charger for the Trim Height Test to prevent battery drain. 3. Using the diagnostic tool, run the Trim Height Test. Self-Test Verify that the following conditions are met before running the On-Demand Self Test. All doors, the liftgate and the liftgate glass must be CLOSED. The transmission is in PARK. The vehicle speed is less than 10 km/h (6 mph). The ignition switch is in the ON position. The vehicle is not in 4L mode. 1. Fulfill the pre-conditions. 2. Install a battery charger for the On-Demand Self Test to prevent battery drain. 3. Run the air suspension On-Demand Self Test. 4. Record all listed DTCs. 5. Retrieve stored DTCs. 6. Troubleshoot any On-Demand Self Test DTCs first. 7. Repeat the On-Demand Self Test and clear DTCs after repairs are completed. Vehicle Dynamic Module (VDM) Diagnostic Trouble Code (DTC) Index Vehicle Dynamic Module (VDM) Diagnostic Trouble Code (DTC) Index NOTE: Repair all other DTCs before C1725 and C1726. Repair DTCs C1990 and C1991 last. DTCs Description Source Action B1317 Battery voltage high VDM GO to Pinpoint Test C. B1318 Battery voltage low VDM GO to Pinpoint Test C.

4 Page 4 of 19 B1342 ECU is defective VDM INSTALL a new VDM. REFER to Air Suspension Module in this section. SET the ride height. REFER to Ride Height Adjustments in this section. CARRY OUT the pneumatic test. TEST the system for normal operation. B2477 VAPS II steering assist curve not complete VDM REFER to Section C1445 Vehicle speed signal circuit failure VDM GO to Symptom Chart. C1724 Air suspension height sensor power circuit failure VDM GO to Pinpoint Test D. C1725 Air suspension front pneumatic failure VDM GO to Pinpoint Test E. C1726 Air suspension rear pneumatic failure VDM GO to Pinpoint Test E. C1760 Air suspension rear height sensor signal circuit failure C1770 Air suspension vent solenoid output circuit failure C1790 Air suspension LR air spring/shock solenoid output circuit failure C1795 Air suspension RR air spring/shock solenoid output circuit failure C1830 Air suspension compressor relay circuit failure VDM GO to Pinpoint Test F. VDM GO to Pinpoint Test G. VDM GO to Pinpoint Test H. VDM GO to Pinpoint Test H. VDM GO to Pinpoint Test N. C1840 Air suspension disable switch circuit failure VDM GO to Pinpoint Test I. C1873 Air suspension RF air spring solenoid output circuit failure C1877 Air suspension LF air spring solenoid output circuit failure C1881 Air suspension RF height sensor circuit failure C1889 Air suspension LF height sensor circuit failure VDM GO to Pinpoint Test H. VDM GO to Pinpoint Test H. VDM GO to Pinpoint Test F. VDM GO to Pinpoint Test F. C1897 Steering VAPS circuit loop failure VDM REFER to Section C1964 Air suspension compressor actual run time exceeded allowed run time C1990 New control module initialization (requires ride height calibration and pneumatic test pass) C1991 Plant ride height setting and/or tests incomplete U1900 Missing CAN message(s) VDM GO to Pinpoint Test N. VDM VDM Door(s) ajar, PRNDL, 4x4, instrument cluster (IC), running boards, vehicle speed REFER to "Clearing DTC C1990 or C1991". REFER to "Clearing DTC C1990 or C1991". REFER to Section U2051 One or more calibration files missing/corrupt VDM CARRY OUT the programmable module installation (PMI) when the original module is not available for the VDM. Refer to Section U2023 Invalid CAN message(s) Door(s) ajar, PRNDL, 4x4, instrument cluster (IC), running boards, vehicle speed REFER to Section Clearing DTC C1990 or C1991 NOTE: Before proceeding with the following steps, make sure that the 4WAS system is fully functional. The vehicle must pass the pneumatic test and have all 3 ride height sensors calibrated for these codes to clear. 1. Either start the vehicle or put vehicle on a battery charger to make sure of sufficient battery voltage. 2. Vent the vehicle down to the kneel position. (Having the key OFF, transmission in PARK, air suspension switch ON and all doors, the liftgate and the liftgate glass CLOSED will make the vehicle kneel.) NOTE: Do not enter the vehicle during this process. The vehicle may not kneel or may kneel very little if the height of the vehicle is near the kneel position. 3. Pump the vehicle to the current calibrated trim height by turning the key to RUN, shifting to DRIVE, and then returning to PARK and closing all vehicle openings. Message center should show no openings ajar. Vehicle will then pump to the currently calibrated trim height. 4. Connect the diagnostic tool to the vehicle. 5. Run the pneumatic test. The tester will indicate if the vehicle has passed the test. NOTE: Passing the pneumatic test does not eliminate the possibility of malfunctioning solenoid valves. 6. After passing the pneumatic test, use the diagnostic tool to retrieve any DTCs. If C1990 or C1991 is present, go to Step 7 and calibrate the ride heights. Otherwise, go to Step NOTE: Manual send mode on the NGS works better than the auto send mode. Using the diagnostic tool, manually raise and lower the vehicle to the correct ride height on an alignment machine and calibrate the ride heights. For additional information, refer to Ride Height Adjustments in this section. 8. Using the diagnostic tool, retrieve the DTCs and verify that all DTCs have been cleared. 9. Drive the vehicle and verify the repair. Verify that the "Check Suspension" message is not present. Make the system vent to kneel position and pump to trim height position several times while verifying system function. Symptom Chart Symptom Chart Condition Possible Sources Action

5 Page 5 of 19 communication with the VDM NOTE: Be sure that the ignition switch is in the ON position and the air suspension service switch is in the ON position before determining that the VDM will not enter the self-test. Fuse(s). Circuitry.. Air suspension service switch.. GO to Pinpoint Test A. GO to Pinpoint Test B. Unable to enter self-test Vehicle raises and/or lowers too slowly Uneven vehicle height The air compressor runs continuously with the ignition switch in the OFF position and no DTC is set Front/rear pneumatic failure. Height sensor. Air compressor assembly. Circuitry. Solenoid. Air line. Front/rear pneumatic failure. Height sensor. Solenoid. Air compressor assembly. Air line. Circuitry. Circuitry. Air suspension relay.. GO to Pinpoint Test E. GO to Pinpoint Test E. GO to Pinpoint Test J. The air suspension system is inoperative without DTCs and vehicle at rest CAN network communication fault. GO to Pinpoint Test K. Air suspension system operates with air suspension service switch in the OFF position Excessive air compressor noise The air compressor is inoperative NOTE: Vehicle speed signal is sent through the CAN communication (secondary) network and it is transmitted by hardwire (primary). DTC C1445: Vehicle Speed Signal Circuit Failure Circuitry. Air suspension switch.. Bracket isolator(s). Mounting bracket. Air compressor assembly. Air compressor assembly in contact with other components. Fuse(s). Air compressor assembly. Circuitry. Air suspension relay. Circuitry. PCM. CAN communication network. GO to Pinpoint Test L. GO to Pinpoint Test M. GO to Pinpoint Test N. REFER to Section Pinpoint Tests Pinpoint Test A: Communication With The Vdm The vehicle dynamic module (VDM) is supplied fused battery voltage through central junction box (CJB) fuse 30 (25A) along circuit 1524 (DB) and fused ignition circuit through CJB fuse 27 (5A) along circuit 1003 (GY/YE). A ground path is provided along circuit 875 (BK/LB). The VDM communicates with the other modules along the CAN communication network. Fuse(s) Circuit open PINPOINT TEST A: NO COMMUNICATION WITH THE VDM NOTICE: The Flex Probe Kit must be used for all test connections. Use of standard multimeter probes may damage wiring terminals. A1 CHECK CIRCUIT 1524 (DB) FOR VOLTAGE Disconnect: VDM 2324a (Expedition),C2131a (Navigator). For Expedition,measure the voltage between: VDM 2324a-1, circuit 1524 (DB), harness side and ground. VDM 2324a-7, circuit 1524 (DB), harness side and ground. For Navigator,measure the voltage between: VDM C2131a-1, circuit 1524 (DB), harness side and ground. VDM C2131a-15, circuit 1524 (DB), harness side and ground. Are the voltages greater than 10 volts? A2 CHECK CIRCUIT 1003 (GY/YE) FOR VOLTAGE For Expedition,measure the voltage between VDM 2324a-10, circuit 1003 (GY/YE), harness side and ground. For Navigator,measure the voltage between VDM C2131a-4, circuit 1003 (GY/YE), harness side and ground. Is the voltage greater than 10 volts? A3 CHECK CIRCUIT 875 (BK/LB) FOR AN OPEN For Expedition,measure the resistance between VDM 2324a-5, circuit 875 (BK/LB), harness side and ground. For Navigator,measure the resistance between VDM C2131a-19, circuit 875 (BK/LB), harness side and ground. GO to A2. Verify CJB fuse 30 (25A) is OK. If OK, REPAIR circuit 1524 (DB) for an open. TEST the system for normal operation. GO to A3. Verify CJB fuse 27 (5A) is OK. If OK, REPAIR circuit 1003 (GY/YE) for an open. TEST the system for normal operation. CHECK the CAN communication network. REFER to Section REPAIR circuit 875 (BK/LB) for an open. TEST the system for normal operation.

6 Page 6 of 19 Pinpoint Test B: Unable To Enter Self-Test The diagnostic tool is used to communicate with the VDM and run the self-test. The vehicle dynamic module (VDM) is supplied fused battery voltage through central junction box (CJB) fuse 30 (25A) along circuit 1524 (DB) and fused ignition circuit through CJB fuse 27 (5A) along circuit 1003 (GY/YE). A ground path is provided along circuit 875 (BK/LB). The VDM communicates with the other modules along the CAN communication network. One of the pre-test conditions are not met PINPOINT TEST B: UNABLE TO ENTER SELF-TEST NOTE: Be sure that the ignition switch is in the ON position and the air suspension service switch is in the ON position before determining that the VDM will not enter the self-test. B1 CHECK THE COMMUNICATION TO THE VDM Verify that the following conditions have been met using the diagnostic tool and monitoring PIDs: Ignition switch is in the ON position. Air suspension service switch is in the ON position. Vehicle speed is less than 3 km/h (2 mph). Transmission selector is in PARK. Battery voltage is greater than 10 volts. Verify that the doors, the liftgate and the liftgate glass are CLOSED. Verify that the power running boards (if equipped), are not deployed. Transfer case is not in 4L mode. Does diagnostic tool communicate with the VDM? INSTALL a new VDM. REFER to Air Suspension Module in this section. REPEAT the self-test. GO to Pinpoint Test A. Pinpoint Test C: DTC B1317/B1318 Battery Voltage High/Low The vehicle dynamic module (VDM) is supplied fused battery voltage through central junction box (CJB) fuse 30 (25A) along circuit 1524 (DB) and fused ignition circuit through CJB fuse 27 (5A) along circuit 1003 (GY/YE). A ground path is provided along circuit 875 (BK/LB). Fuse(s) Circuit open PINPOINT TEST C: DTC B1317/B1318 BATTERY VOLTAGE HIGH/LOW NOTICE: The Flex Probe Kit must be used for all test connections. Use of standard multimeter probes may damage wiring terminals. C1 VERIFY DTC B1317 AND/OR B1318 Connect the scan tool. Clear any DTCs and carry out the On-Demand Self Test. Is DTC B1317 or B1318 retrieved? C2 CHECK THE BATTERY VOLTAGE Measure the battery voltage between the positive and negative battery posts with the key ON engine OFF (KOEO), and with the engine running. Is the battery voltage between 10 and 13 volts with KOEO, and between 11 and 18 volts with the engine running? C3 CHECK VOLTAGE TO THE VDM Disconnect: VDM C2324a (Expedition),C2131a (Navigator). For Navigator, measure the voltage between the following VDM,C2131a pins, harness side and ground with the key ON engine OFF (KOEO), and with the engine running: VDM Connector C2131a Pin. Circuit (DB) (GY/YE) (DB) GO to C2. TEST the vehicle for normal operation. GO to C3. REFER to Section TEST the system for normal operation. GO to C4. Verify CJB fuse 30 (25A) and fuse 27 (5A) are OK. If OK, REPAIR the affected circuit(s) for an open. CLEAR the DTCs. REPEAT the self-test. For Expedition, measure the voltage between the following VDM 2324a (Expedition),C2131a (Navigator) pins, harness side and ground with the key ON engine OFF (KOEO), and with the engine running: VDM Connector C2324a Pin. Circuit (DB) (GY/YE) (DB) Is the voltage between 10 and 13 volts with KOEO, and between 11 and 18 volts with the engine running?

7 Page 7 of 19 C4 CHECK CIRCUIT 875 (BK/LB) FOR AN OPEN For Expedition,measure the resistance between VDM C2324a-5, circuit 875 (BK/LB), harness side, and ground. For Navigator,measure the resistance between VDM C2131a-19, circuit 875 (BK/LB), harness side, and ground. INSTALL a new VDM. REFER to Air Suspension Module in this section. REPAIR circuit 875 (BK/LB) for an open. CLEAR the DTCs. Pinpoint Test D: DTC C1724 Air Suspension Height Sensor Power Circuit Failure The 2 front height sensors receive a 5-volt reference voltage from the vehicle dynamic module (VDM) along circuit 426 (RD/BK) and ground along circuit 432 (BK/PK). The rear height sensor receives a 5-volt reference voltage from the VDM along circuit 429 (VT/LG) and ground along circuit 432 (BK/PK). The air suspension service switch is a normally-closed switch that is used to turn the vehicle dynamic suspension system ON and OFF. The vehicle dynamic module (VDM) sends voltage along circuit 429 (VT/LG) into the switch and looks for that voltage to return along circuit 418 (DG/YE). If the VDM does not receive voltage along circuit 418 (DG/YE) it will deactivate the vehicle dynamic suspension system. Circuit open Circuit shorted Height sensor(s) PINPOINT TEST D: DTC C1724 AIR SUSPENSION HEIGHT SENSOR POWER CIRCUIT FAILURE NOTICE: The Flex Probe Kit must be used for all test connections. Use of standard multimeter probes may damage wiring terminals. D1 CHECK THE AIR SUSPENSION HEIGHT SENSOR POWER CIRCUITS FOR AN OPEN Disconnect: VDM 2324a (Expedition),C2131a (Navigator). Disconnect: VDM 2324b (Expedition),C2131b (Navigator). Disconnect: LF Height Sensor C1153. Disconnect: RF Height Sensor C1151. Disconnect: Rear Height Sensor C4084. For Expedition,measure the resistance between: VDM 2324a-3, circuit 426 (RD/BK), harness side and LF height sensor C1153-3, circuit 426 (RD/BK). VDM 2324a-3, circuit 426 (RD/BK), harness side and RF height sensor C1151-3, circuit 426 (RD/BK). VDM 2324b-7, circuit 429 (VT/LG), harness side and rear height sensor C4084-3, circuit 429 (VT/LG). For Navigator,measure the resistance between: VDM C2131a-17, circuit 426 (RD/BK), harness side and LF height sensor C1153-3, circuit 426 (RD/BK). VDM C2131a-17, circuit 426 (RD/BK), harness side and RF height sensor C1151-3, circuit 426 (RD/BK). VDM C2131b-8, circuit 429 (VT/LG), harness side and rear height sensor C4084-3, circuit 429 (VT/LG). Are the resistances less than 5 ohms? D2 CHECK THE AIR SUSPENSION HEIGHT SENSOR POWER CIRCUITS FOR A SHORT TO GROUND For Expedition,measure the resistance between ground and: VDM 2324a-3, circuit 426 (RD/BK), harness side. VDM 2324b-7, circuit 429 (VT/LG), harness side. LF height sensor C1153-3, circuit 426 (RD/BK), harness side. RF height sensor C1151-3, circuit 426 (RD/BK), harness side Rear height sensor C4084-3, circuit 429 (VT/LG), harness side. For Navigator,measure the resistance between ground and: VDM C2131a-17, circuit 426 (RD/BK), harness side. VDM C2131b-8, circuit 429 (VT/LG), harness side. LF height sensor C1153-3, circuit 426 (RD/BK), harness side. RF height sensor C1151-3, circuit 426 (RD/BK), harness side Rear height sensor C4084-3, circuit 429 (VT/LG), harness side. Are the resistances greater than 10,000 ohms? D3 CHECK THE AIR SUSPENSION HEIGHT SENSOR SIGNAL RETURN CIRCUITS FOR AN OPEN For Expedition,measure the resistance between: VDM 2324a-6, circuit 432 (BK/PK), harness side and RF height sensor C1153-1, circuit 432 (BK/PK), harness side. VDM 2324a-6, circuit 432 (BK/PK), harness side and LF height sensor C1151-1, circuit 432 (BK/PK), harness side. VDM 2324a-9, circuit 432 (BK/PK), harness side and rear height sensor C4084-1, circuit 432 (BK/PK) harness side. For Navigator,measure the resistance between: VDM C2131a-20, circuit 432 (BK/PK), harness side and RF height sensor C1153-1, circuit 432 (BK/PK), harness side. VDM C2131a-20, circuit 432 (BK/PK), harness side and LF height sensor C1151-1, circuit 432 (BK/PK), harness side. VDM C2131b-10, circuit 432 (BK/PK), harness side and rear height sensor C4084-1, circuit 432 (BK/PK) harness side. Are the resistances less than 5 ohms? D4 CHECK THE AIR SUSPENSION SWITCH Place the air suspension switch in the ON position. For Expedition,measure the resistance between VDM 2324b-5, circuit 418 (DG/YE), harness side and 2324b-7, circuit 429 (VT/LG), harness side. For Navigator,measure the resistance between VDM C2131b-25, circuit 418 (DG/YE), harness side and C2131b-8, circuit 429 (VT/LG), harness side. GO to D2. REPAIR the affected circuit(s) for an open. CLEAR the DTCs. GO to D3. REPAIR the affected circuit(s) for a short to ground. CLEAR the DTCs. GO to D4. REPAIR circuit 432 (BK/PK) for an open. CLEAR the DTCs. GO to D5. REPAIR the affected circuit(s) for an open. CLEAR the DTCs.

8 Page 8 of 19 D5 CHECK CIRCUITS 426 (RD/BK) AND 429 (VT/LG) FOR A SHORT TO GROUND Place the air suspension switch in the ON position. For Expedition,measure the resistance between VDM 2324a-3, circuit 426 (RD/BK), harness side and ground; and measure the resistance between VDM 2324b-7, circuit 429 (VT/LG), harness side and ground. For Navigator,measure the resistance between VDM C2131a-17, circuit 426 (RD/BK), harness side and ground; and measure the resistance between VDM C2131b-8, circuit 429 (VT/LG), harness side and ground. Are the resistances greater than 10,000 ohms? D6 CHECK VOLTAGE AT THE LF, RF AND REAR HEIGHT SENSORS Connect: VDM 2324a (Expedition),C2131a (Navigator). Connect: VDM 2324b (Expedition),C2131b (Navigator). Measure the voltage between: LF height sensor C1153-1, circuit 432 (BK/PK), harness side and LF height sensor C1153-3, circuit 432 (BK/PK), harness side. RF height sensor C1151-1, circuit 432 (BK/PK), harness side and RF height sensor C1151-3, circuit 426 (RD/BK) harness side. Measure the voltage between rear height sensor C4084-1, circuit 432 (BK/PK), harness side and C4084-3, circuit 429 (VT/LG), harness side. Are the voltages 5 volts? GO to D6. REPAIR the affected circuit(s) for an open. CLEAR the DTCs. INSTALL a new height sensor(s) as necessary. REFER to Suspension Height Sensor in this section. CLEAR the DTCs. INSTALL a new VDM. REFER to Air Suspension Module in this section. CLEAR the DTCs. Pinpoint Test E: DTCs C1725/C1736 Air Suspension Front/Rear Pneumatic Failure The vehicle dynamic module (VDM) will command the air compressor and air solenoid valves to either fill or vent the air springs depending on the input from the 3 height sensors. The air compressor sends the air to the air springs first through the drier, then along the air lines, passing through several T-fittings and connections, through the air solenoid valves and finally to the air springs. Air leak(s) Air line blockage(s) Air line(s) Mounting bracket(s) Air compressor drier Air spring solenoid valve(s) Height sensor(s) Air compressor Air spring(s) PINPOINT TEST E: DTCs C1725/C1726 AIR SUSPENSION FRONT/REAR PNEUMATIC FAILURE NOTE: It may be necessary to vent air from the front air suspension air springs during this pinpoint test. E1 CHECK THE AIR SUSPENSION HEIGHT SENSORS Inspect the LF, RF and rear air suspension height sensors for correct installation at the upper and lower ball studs. Inspect the air suspension height sensor mounting brackets for damage. Verify that all air lines are fully seated. Are the air suspension height sensors, mounting brackets and air lines OK? E2 CHECK THE AIR SUSPENSION HEIGHT SENSOR OPERATION Turn the air suspension switch to the OFF position. Disconnect the sensor arm linkage from the LF, RF and rear air suspension height sensors. Connect the scan tool. NOTE: The voltage will increase as the suspension is compressed. While monitoring the VDM LF, RF and rear height sensor PID display, slowly move the LF, RF and rear air suspension height sensors through its full travel UP and DOWN. Do the voltages vary from approximately 0.50 volt and 4.50 volts? E3 VERIFY THAT THE FRONT CAN BE RAISED Trigger the VDM LF and RF suspension fill active commands. Allow the vehicle to raise for 30 seconds. Monitor all 3 height sensor voltage PIDs. Did the LF and RF raise and the rear remain at the same height? E4 VERIFY THAT THE REAR CAN BE RAISED Trigger the VDM rear suspension fill active command. Allow the vehicle to raise for 30 to 45 seconds. Monitor all 3 height sensor voltage PIDs. Did the rear raise and the LF and RF remain at the same height? E5 VERIFY THAT THE AIR SPRING SOLENOIDS DO NOT LEAK Disconnect the air line at the right rear air spring solenoid valve. Use a thumb to block and unblock the end of the disconnected air line as the air escapes. Can air pressure be felt when the air line is blocked? GO to E2. REPAIR as necessary. If the height sensor mounting brackets are installed or repaired, RESET front ride height. REFER to Ride Height Adjustments in this section. CLEAR the DTCs. RECONNECT the sensor arm linkages to the air suspension height sensors. GO to E3. INSTALL a new height sensor(s). REFER to Suspension Height Sensor in this section. CLEAR the DTCs. TRIGGER the VDM off active command. GO to E4. TRIGGER the VDM off active command. If the front remained at the same height, GO to E6 ; if the rear raised, GO to E4. TRIGGER the VDM off active command. GO to E6. TRIGGER the VDM off active command. If the rear raised and the LF and RF raised, GO to E5 ; if the rear did not raise and LF and RF remained at the same height, GO to E7. IDENTIFY the leaking air spring solenoid valve by observing which air spring assembly continues to vent with the air line blocked. INSTALL a new air spring solenoid valve. REFER to Air Spring Solenoid Valve in this section. CLEAR the DTCs.

9 Page 9 of 19 E6 VERIFY THAT THE VEHICLE CAN BE LOWERED Trigger the VDM vent front and rear air suspension active commands. Allow the front and rear to lower for 30 seconds. Does the vehicle lower evenly? GO to E6. INSTALL a new VDM. REFER to Air Suspension Module in this section. E7 CHECK OPERATION OF THE AIR COMPRESSOR NOTICE: The VDM limits the air compressor run time. If the air compressor overheats, it will not restart until it cools down. The ignition switch must be in the OFF position to allow the compressor thermal switch to cool. Trigger the VDM compressor on active command. Does the air compressor run (slight buzzing noise from RF fender)? E8 CHECK THE AIR COMPRESSOR PRESSURE OUTPUT NOTICE: The VDM limits the air compressor run time. If the air compressor overheats, it will not restart until it cools down. The ignition switch must be in the OFF position to allow the compressor thermal switch to cool. NOTE: If fluid is present when disconnecting an air line, clear the air lines. Refer to Air Line Fluid Purge procedure in this section. Check the compressor air drier for water or the front air spring for oil. NOTE: When triggering the compressor ON, the vent solenoid will open as well. To prevent the vent solenoid from opening during this test, first trigger a single spring solenoid ON, then trigger the compressor ON. Disconnect air line T-fitting at the right front shock tower. Connect an air pressure gauge (1,723 kpa [250 psi] maximum reading) with common fittings to the air line going to the compressor air drier. Trigger the VDM compressor on active command. Run the air compressor for 30 seconds. Wait 5 minutes. Trigger the VDM compressor vent on active command. Did the compressor produce 1,034 kpa (150 psi) within 30 seconds and hold developed pressure during the 5 minutes? E9 CHECK THE AIR DRIER FOR LEAKS NOTICE: The VDM limits the air compressor run time. If the air compressor overheats, it will not restart until it cools down. The ignition switch must be in the OFF position to allow the compressor thermal switch to cool. NOTE: Apply a soap and water solution to the air lines and air line connections when checking for air suspension system leakage. NOTE: When triggering the compressor ON, the vent solenoid will open as well. To prevent the vent solenoid from opening during this test, first trigger a single spring solenoid ON, then trigger the compressor ON. Trigger the VDM compressor on active command. Thoroughly inspect the air drier-to-air compressor connection. Is the air drier leaking at the air compressor? E10 CHECK THE SPRING SOLENOID OPERATION NOTE: Start with the vehicle at trim height before carrying out this test step. NOTE: Air will vent much faster with the air lines disconnected from each spring solenoid. Disconnect the air line at the LF, RF, LR and RR air spring solenoids. Trigger the VDM LF, RF, LR and RR air spring solenoid valve vent active commands. Does each air solenoid vent? E11 CHECK THE AIR LINE FROM THE AIR DRIER NOTICE: The VDM limits the air compressor run time. If the air compressor overheats, it will not restart until it cools down. The ignition switch must be in the OFF position to allow the compressor thermal switch to cool. NOTE: Apply a soap and water solution to the air lines and air line connections when checking for air suspension system leakage. Trigger the VDM compressor on active command. Check for excessive air leaks, kinked or pinched air lines between the air compressor and the LF, RF, LR and RR air spring solenoids and between the air compressor and the air pressure gauge. Are there any excessive leaks, kinks or pinched air lines? E12 CHECK FOR A PLUGGED AIR LINE Disconnect the air line from the air drier. Trigger the front and rear suspension vent active commands. Does the vehicle lower at an acceptable rate? E13 CHECK FOR A PLUGGED AIR DRIER Disconnect the air drier from the air compressor. Connect the air line to the air drier. Trigger the front and rear suspension vent active commands. Does the vehicle lower at an acceptable rate? E14 CHECK FOR A BLOCKAGE IN THE AIR LINE TO EACH AIR SPRING NOTE: If fluid is present when disconnecting an air line, clear the air lines. Refer to Air Line Fluid Purge in this section. Check the air compressor air drier for water and check the air springs for oil. Disconnect the air line at the LF, RF, LR and RR air spring. Disconnect the air line at the air drier. Connect the vacuum tester at the suspect air spring air line and try to draw a vacuum. Can a vacuum be drawn and held? GO to E11. TRIGGER the VDM compressor off active command. GO to E8. TRIGGER the VDM compressor off active command. GO to Pinpoint Test N. GO to E10. GO to E9. INSTALL a new air drier. REFER to Air Suspension Compressor Drier in this section. CLEAR the DTCs. GO to E10. GO to E11. INSTALL a new air spring solenoid valve(s). REFER to Air Spring Solenoid Valve in this section. CLEAR the DTCs. CARRY OUT the Pneumatic Test. INSTALL new or REPAIR the air line where necessary. CLEAR the DTCs. GO to E12. GO to E13. GO to E14. INSTALL a new air drier. REFER to Air Suspension Compressor Drier in this section. CLEAR the DTCs. GO to E14. REPAIR the blockage in the affected air line(s). CLEAR the DTCs. REPEAT the self-test. GO to E15.

10 Page 10 of 19 E15 CHECK THE AIR SPRINGS FOR LEAKS NOTE: If fluid is present when disconnecting an air line, clear the air lines. Refer to Air Line Fluid Purge in this section. Check the air compressor air drier for water and check the air springs for oil. Trigger the VDM to fill the suspect air spring(s). Using a soap and water solution, check the air spring for leaks at the upper mount and sleeve areas. Are any leaks detected? INSTALL a new air spring(s). REFER to Air Shock Absorber Front or Air Shock Absorber Rear in this section. CLEAR the DTCs. REPEAT the selftest. CARRY OUT the Pneumatic Test in this section. INSTALL a new VDM. REFER to Air Suspension Module in this section. Pinpoint Test F: DTC C1760 (Rear), C1881 (RF), C1889 (LF) Air Suspension Height Sensor Signal Circuit Failure The 2 front height sensors receive a 5-volt reference voltage from the vehicle dynamic module (VDM) along circuit 426 (RD/BK) and ground along circuit 432 (BK/PK). The rear height sensor receives a 5-volt reference voltage from the VDM along circuit 429 (VT/LG) and ground along circuit 432 (BK/PK). Circuit open Circuit shorted Height sensor(s) PINPOINT TEST F: DTC C1760 (REAR), C1881 (RF), C1889 (LF) AIR SUSPENSION HEIGHT SENSOR SIGNAL CIRCUIT FAILURE NOTICE: The Flex Probe Kit must be used for all test connections. Use of standard multimeter probes may damage wiring terminals. F1 VALIDATE THE DTC ERROR Carry out the VDM On-Demand Self Test. Is the same air suspension height sensor DTC set? GO to F2. F2 CHECK THE AIR SUSPENSION HEIGHT SENSOR SIGNAL RETURN CIRCUIT FOR AN OPEN Disconnect: Air Suspension Service Switch C4169. Disconnect: VDM 2324a (Expedition),C2131a (Navigator). Disconnect: VDM 2324b (Expedition),C2131b (Navigator). Disconnect: Suspect Height Sensor. For Expedition,measure the resistance between the suspect height sensor connector pin 1 harness side, circuit 432 (BK/PK) and VDM2324a-6 (front sensors) or2324b-9 (rear sensor), harness side. If no DTC is retrieved, GO to F5. If a different DTC is retrieved, REFER to the VDM Diagnostic Trouble Code (DTC) Index. GO to F3. REPAIR circuit 432 (BK/PK) for an open. CLEAR the DTCs. Air Suspension Height Sensor Air Suspension Height Sensor Connector. Left Front (LF) Right Front (RF) Rear C1153 C1151 C4084 For Navigator,measure the resistance between the suspect height sensor connector pin 1 harness side, circuit 432 (BK/PK) and VDM C2131a-20 (front sensors) or C2131b-10 (rear sensor), harness side. Air Suspension Height Sensor Air Suspension Height Sensor Connector. Left Front (LF) Right Front (RF) Rear C1153 C1151 C4084 F3 CHECK THE VDM POWER AND RETURN CIRCUITS FOR VOLTAGE For DTC C1760, measure the voltage between rear height sensor C4084-1, circuit 432 (BK/PK) harness side and rear height sensor C4084-3, circuit 429 (VT/LG) harness side. For DTC C1881 (RF), measure the voltage between RF height sensor C1151-1, circuit 432 (BK/PK) harness side and RF height sensor C1151-3, circuit 426 (RD/BK) harness side. For DTC C1889 (LF), measure the voltage between LF height sensor C1153-1, circuit 432 (BK/PK) harness side and LF height sensor C1153-3, circuit 426 (RD/BK) harness side. Is the voltage approximately 5 volts? F4 CHECK THE AIR SUSPENSION HEIGHT SENSOR POWER CIRCUIT FOR A SHORT TO VOLTAGE For Expedition,measure the voltage between ground and: VDM 2324a-3, circuit 426 (RD/BK), harness side. VDM 2324b-7, circuit 429 (VT/LG), harness side. For Navigator,measure the voltage between ground and: VDM C2131a-17, circuit 426 (RD/BK), harness side. VDM C2131b-8, circuit 429 (VT/LG), harness side. Is voltage present? F5 CHECK THE AIR SUSPENSION HEIGHT SENSOR SIGNAL RETURN CIRCUITS FOR A SHORT TO VOLTAGE Disconnect: VDM 2324a (Expedition),C2131a (Navigator). Disconnect: VDM 2324b (Expedition),C2131b (Navigator). For Expedition,measure the voltage between ground and: GO to F8. GO to F4. REPAIR the affected circuit(s) for a short to voltage. CLEAR the DTCs. GO to F5. REPAIR circuit 432 (BK/PK) for a short to voltage. CLEAR the DTCs.

11 Page 11 of 19 VDM 2324a-6, circuit 432 (BK/PK), harness side. VDM 2324b-9, circuit 432 (BK/PK), harness side For Navigator,measure the voltage between ground and: VDM C2131a-20, circuit 432 (BK/PK), harness side. VDM C2131b-10, circuit 432 (BK/PK), harness side Is voltage present? F6 CHECK THE AIR SUSPENSION HEIGHT SENSOR SIGNAL RETURN CIRCUITS FOR AN OPEN For Expedition front height sensors(s), measure the voltage between VDM 2324a-6, circuit 432 (BK/PK), harness side and the suspect height sensor pin 1, harness side. For rear height sensor, measure the voltage between VDM 2324b-9, circuit 432 (BK/PK), harness side rear height sensor pin 1, harness side. Air Suspension Height Sensor Air Suspension Height Sensor Connector. Left Front (LF) Right Front (RF) Rear C1153 C1151 C4084 GO to F6. GO to F7. REPAIR circuit 432 (BK/PK) for an open. CLEAR the DTCs. For Navigator front height sensors(s), measure the voltage between VDM C2131a-20, circuit 432 (BK/PK), harness side and the suspect height sensor pin 1, harness side. For rear height sensor, measure the voltage between VDM C2131b-10, circuit 432 (BK/PK), harness side rear height sensor pin 1, harness side. Air Suspension Height Sensor Air Suspension Height Sensor Connector. Left Front (LF) Right Front (RF) Rear C1153 C1151 C4084 F7 CHECK THE AIR SUSPENSION HEIGHT SENSOR SIGNAL RETURN CIRCUITS FOR A SHORT TO GROUND For Expedition front height sensor(s), measure the resistance between VDM 2324a-6, circuit 432 (BK/PK), harness side and ground. For rear height sensor, measure the resistance between VDM 2324b-9, circuit 432 (BK/PK), harness side and ground. Air Suspension Height Sensor Air Suspension Height Sensor Connector. Left Front (LF) Right Front (RF) Rear For Navigator front height sensor(s), measure the resistance between VDM C2131a-20, circuit 432 (BK/PK), harness side and ground. For rear height sensor, measure the resistance between VDM C2131b-10, circuit 432 (BK/PK), harness side and ground. Is the resistance greater than 10,000 ohms? C1153 C1151 C4084 Air Suspension Height Sensor Air Suspension Height Sensor Connector. Left Front (LF) Right Front (RF) Rear F8 CHECK THE HEIGHT SENSOR OUTPUT C1153 C1151 C4084 Connect: Air Suspension Service Switch C4169. Connect: VDM 2324a (Expedition),C2131a (Navigator). Connect: VDM 2324b (Expedition),C2131b (Navigator). Connect: Height Sensor(s). Disconnect the suspect height sensor linkage from the height sensor ball stud. For Expedition LF or RF height sensor: using a multimeter set to DC voltage, back-probe the VDM2324a-3 and 2324a-6. Rear height sensor: using a multimeter set to DC voltage, back-probe the VDM2324b-8 and 2324b-9. For Navigator LF or RF height sensor: using a multimeter set to DC voltage, back-probe the VDM C2131a-17 and C2131a-20. Rear height sensor: using a multimeter set to DC voltage, back-probe the VDM2131b-9 and C2131b-10. Move the suspect height sensor arm through its full range of motion. Does the voltage vary from approximately 0.50 volt to 4.5 volts? GO to F8. REPAIR circuit 432 (BK/PK) for a short to ground. CLEAR the DTCs. INSTALL a new VDM. REFER to Air Suspension Module in this section. INSTALL a new height sensor(s) as necessary. REFER to Suspension Height Sensor in this section. CLEAR the DTCs. Pinpoint Test G: DTC C1770 Air Suspension Vent Solenoid Output Circuit Failure The vehicle dynamic module (VDM) will command the air suspension system vent solenoid ON or OFF when certain conditions are met. The VDM supplies voltage to the vent solenoid through circuit 421 (PK) which activates the vent solenoid and vents the air suspension system. The vent solenoid is grounded through circuit 57 (BK). Electrical connector(s) Circuit open Circuit shorted Air compressor PINPOINT TEST G: DTC C1770 AIR SUSPENSION VENT SOLENOID OUTPUT CIRCUIT FAILURE NOTICE: The Flex Probe Kit must be used for all test connections. Use of standard multimeter probes may damage wiring terminals. G1 VALIDATE DTC C1770 Carry out VDM On-Demand Self Test.

12 Page 12 of 19 Is the same air suspension DTC set? GO to G2. G2 CHECK THE VENT SOLENOID CONNECTOR Disconnect: Air Compressor Assembly C1179. Inspect the pins and terminals of the air compressor assembly connector for corroded, damaged or backed out pins, moisture or other damage. Is the air compressor assembly C1179 OK? G3 CHECK THE VENT SOLENOID PID Connect: Air Compressor Assembly C1179. Turn the air suspension service switch to the ON position. Trigger the VDM vent ON and vent OFF active command. Do the letters O, G or B appear next to the ON/OFF text for the air suspension vent solenoid? G4 CHECK CIRCUIT 57 (BK) FOR AN OPEN Disconnect: Air Compressor Assembly C1179. Measure the resistance between air compressor assembly C1179-2, circuit 57 (BK), harness side and ground. G5 CHECK THE VENT SOLENOID FOR AN OPEN OR SHORT Measure the resistance between air compressor C and C1179-1, component side. Is the resistance between 17 and 22 ohms? G6 CHECK CIRCUIT 421 (PK) FOR AN OPEN Disconnect: VDM C2131b. Measure the resistance between VDM C2131b-5, circuit 421 (PK), harness side and air compressor assembly C1179-2, circuit 421 (PK), harness side. G7 CHECK CIRCUIT 421 (PK) FOR A SHORT TO GROUND Measure the resistance between VDM C2131b-5, circuit 421 (PK), harness side and ground. Is the resistance greater than 10,000 ohms? G8 CHECK CIRCUIT 421 (PK) FOR A SHORT TO VOLTAGE Measure the voltage between VDM C2131b-5, circuit 421 (PK), harness side and ground. Is the voltage at zero? CHECK the VDM and air compressor harness connectors for corroded, damaged or backed out pins, moisture or other damage. CARRY OUT the pneumatic test. If other DTCs are present, REFER to the VDM Diagnostic Trouble Code (DTC) Index. GO to G3. REPAIR the connector as necessary. CLEAR the DTCs. If O appeared, GO to G4. If G appeared, GO to G5. If B appeared, GO to G7. CLEAR the DTCs. GO to G5. REPAIR circuit 57 (BK) for an open. CLEAR the DTCs. GO to G6. INSTALL a new air compressor. REFER to Air Suspension Compressor in this section. CLEAR the DTCs. GO to G7. REPAIR circuit 421 (PK) for an open. CLEAR the DTCs. GO to G8. REPAIR circuit 421 (PK) for a short to ground. CLEAR the DTCs. INSTALL a new VDM. REFER to Air Suspension Module in this section. REPAIR circuit 421 (PK) for a short to voltage. CLEAR the DTCs. Pinpoint Test H: DTC C1790 (LR), C1795 (RR), C1873 (RF), C1877 (LF) Air Suspension Air Spring Solenoid Output Circuit Failure The vehicle dynamic module (VDM) will command the air spring solenoid(s) ON or OFF when certain conditions are met. The left front solenoid receives voltage from the VDM along circuit 415 (LG/OG) and ground along 57 (BK), the right front solenoid receives voltage from the VDM along circuit 414 (OG/RD) and ground along 57 (BK), the left rear solenoid receives voltage from the VDM along circuit 1114 (BN/PK) and ground along 57 (BK) and the right rear solenoid receives voltage from the VDM along circuit 1115 (TN/WH) and ground along 57 (BK). Fuse(s) Circuit open Circuit shorted Air solenoid(s) PINPOINT TEST H: DTC C1790 (LR), C1795 (RR), C1873 (RF), C1877 (LF) AIR SUSPENSION AIR SPRING SOLENOID OUTPUT CIRCUIT FAILURE NOTICE: The Flex Probe Kit must be used for all test connections. Use of standard multimeter probes may damage wiring terminals. H1 VALIDATE THE DTC Carry out the VDM On-Demand Self Test. Is DTC C1790, C1795, C1873 or C1877 set? GO to H2. H2 CHECK THE AIR SUSPENSION AIR SPRING SOLENOID CONNECTOR(S) If no DTCs are retrieved, GO to H10. If different DTCs are retrieved, REFER to VDM Diagnostic Trouble Code (DTC) Index. GO to H3.