Rear Air Springs Do Not Deflate

Rear Air Springs Do Not Deflate

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (Diagnostic System Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Strategy Based Diagnosis) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Diagnostic Procedure Instructions) provides an overview of each diagnostic category.

Diagnostic Fault Information





Circuit/System Description

The air suspension system utilizes left and right rear air suspension sensors to determine the calibrated level of the vehicle. As weight is added to the rear of the vehicle, the sensors signal to the air suspension compressor change which activates the compressor to raise the vehicle to the proper height. Upon removal of the additional weight, the sensor signals the compressor to exhaust enough air to lower the vehicle back down to maintain the calibrated rear trim height.

Reference Information
Schematic Reference

Air Suspension Schematics (Electrical Diagrams)
Connector End View Reference

Component Connector End Views (Connector Views)
Description and Operation

Air Suspension Description and Operation (Description and Operation)
Electrical Information Reference

* Circuit Testing (Circuit Testing)
* Connector Repairs (Connector Repairs)
* Testing for Intermittent Conditions and Poor Connections (Testing for Intermittent Conditions and Poor Connections)
* Wiring Repairs (Wiring Repairs)

Circuit/System Verification

Ignition ON, load the vehicle with additional weight in the rear. The air suspension compressor should activate raising the vehicle to the calibrated vehicle level. Remove the additional load and the compressor will exhaust the necessary amount of air to return to the calibrated vehicle level.

Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the air suspension compressor assembly.
2. Test for less than 2.0 ohms between the low reference circuit connector X1, terminal D and ground.

• If greater than the specified value, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the air suspension compressor assembly.

3. Ignition ON, verify that a test lamp illuminates between the compressor B+ circuit connector X1, terminal H and ground.

• If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal, test or replace the air suspension compressor assembly.

4. Ignition ON, verify that a test lamp illuminates between the compressor IGN 3 circuit connector X1, terminal G and ground.

• If the test lamp does not illuminate, test the IGN 3 circuit for a short to ground or an open/high resistance. If the circuit tests normal, test or replace the air suspension compressor assembly.
• If the circuit tests normal, replace the air suspension compressor assembly.

Repair Instructions

Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.

* Air Suspension Depressurization (Air Suspension Depressurization)
* Automatic Level Control Air Compressor Replacement (Service and Repair)
* Rear Air Spring Level Sensor Calibration (Rear Air Spring Level Sensor Calibration)