Your best bet take it an have it diagnosed ! This is computer controlled an may have DTC'S - diagnostic trouble codes stored !
C1724
Air Suspension Height Sensor Power Circuit Failure
Air Suspension Control Module
GO to Pinpoint Test F .
C1726
Air Suspension Rear Pneumatic Failure
Air Suspension Control Module
GO to Pinpoint Test G .
C1760
Air Suspension Rear Height Sensor High Signal Circuit Failure
Air Suspension Control Module
GO to Pinpoint Test H .
C1770
Air Suspension Vent Solenoid Output Circuit Failure
Air Suspension Control Module
GO to Pinpoint Test I .
C1790
Air Suspension LR Air Spring Solenoid Output Circuit Failure
Air Suspension Control Module
GO to Pinpoint Test J .
C1795
Air Suspension RR Air Spring Solenoid Output Circuit Failure
Air Suspension Control Module
GO to Pinpoint Test K .
C1830
Air Suspension Compressor Relay Circuit Failure
Air Suspension Control Module
GO to Pinpoint Test L
Symptom Chart
Condition
Possible Sources
Action
- No communication with the air suspension control module
- CJB Fuse 4 (15A), 6 (5A) and 20 (5A).
- Circuitry.
- Air suspension control module.
- Air suspension switch.
You replaced a part that you probably didn't need !
- The compressor is inoperative
- BJB Fuse 109 (50A).
- Air compressor assembly.
- Circuitry.
- Air suspension relay.
There is a lot to this system an guessing as to what the problem is ,isn't the way to fix it.
Measure the voltage between air compressor relay C1000 Pin A, Circuit 1053 (LB/PK), harness side and ground.
- Is the voltage greater than 10 volts?
Yes GO to Q3 .
No REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test.
Measure the resistance between air compressor C1000 Pin B, Circuit 538 (GY/RD), harness side and air compressor assembly C194M Pin 4, Circuit 538 (GY/RD), harness side.
- Is the resistance less than 5 ohms?
Yes GO to Q4 .
No REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test.
Air Suspension Height Sensor
One air suspension height sensor is mounted on the vehicle. The air suspension height sensor sends a voltage signal to the air suspension control module. The output ranges from approximately 4.75 volts at minimum height (when the vehicle is low or in full jounce), to 0.25 volts at maximum height (when the vehicle is high or in full rebound). The air suspension height sensor has a useable range of 80 mm (3.2 in) compared to total suspension travel of 200-250 mm (8 to 10 in) at the wheel. Therefore, the air suspension height sensor is mounted to the suspension at a point where full rear suspension travel at the wheel is relative to 80 mm (3.2 in) of travel at the air suspension height sensor. The air suspension height sensor is attached between the No. 5 frame crossmember (upper socket) and the panhard rod (lower socket). Replace the air suspension height sensor as a unit.
When the air suspension height sensor indicates that the rear of the vehicle is lower than trim under normal driving conditions, the air compressor will turn on and pump compressed air to the air springs. When the sensor indicates that the rear of the vehicle is raised above trim under normal driving conditions, this will cause the air to be vented from the air springs to lower the vehicle back to its trim height level.
Compressor Relay
The compressor relay is energized by the air suspension control module to allow high current to flow from the battery to the compressor motor.
- A solid state relay is used in the air suspension system for air compressor control. The relay incorporates a custom power metal oxide semi-conductor field effect transistor (MOSFET) and ceramic hybrid circuitry. The relay switches high current loads in response to low power signals and is controlled by the logic of the air suspension control module.
- Air Suspension Control Module
NOTE: The 4WAS air suspension control module is used for the RAS system. The internal processor recognizes external circuitry to determine if it is installed in a 4WAS or a RAS equipped vehicle.
NOTE: The air suspension control module is calibrated with information from the air suspension height sensor. A new or exchanged air suspension control module requires a ride height adjustment calibration process to be performed.
The air suspension control module controls the air compressor motor (through a solid state relay), and the air spring solenoids. The air suspension control module also provides power to the air suspension height sensor. The air suspension control module controls vehicle height adjustments by monitoring the air suspension height sensor, vehicle speed, a steering sensor, acceleration input, the door ajar signal, transfer case signals, and the brake pedal position (BPP) switch. The air suspension control module also conducts all fail-safe and diagnostic strategies and contains self-test and communication software for testing the vehicle and related components.
The air suspension control module monitors and controls the air suspension system through a 32-pin two-way connector. The air suspension control module is keyed so that the air suspension control module cannot be plugged into an incorrect harness. There are two sides of the harness connection to the air suspension control module. Each is uniquely colored and keyed to prevent reversing the connections.
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