GM Service Manual Online
For 1990-2009 cars only

Diagnostic Instructions

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

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

Air Suspension Compressor Assembly Battery Positive Voltage Circuit

1, 2, 4, 6

1, 2, 4, 6

--

--

Air Suspension Compressor Assembly Ignition 3 Voltage Circuit

1, 2, 4, 6

1, 2, 4, 6

--

--

Air Suspension Compressor Assembly Ground Circuit

--

1, 2, 4, 6

--

--

Air Suspension Inflator Switch Ground Circuit

--

4, 6

--

--

Air Suspension Inflator Switch Indicator Control Circuit

4

4

3

--

Air Suspension Inflator Switch Signal Circuit

5

6

6

--

Left Rear Air Suspension Sensor Low Reference Circuit

--

DTC 002

--

--

Left Rear Air Suspension Sensor Signal Circuit

DTC 002

DTC 002

DTC 002

--

Right Rear Air Suspension Sensor Low Reference Circuit

--

DTC 003

--

--

Right Rear Air Suspension Sensor Signal Circuit

DTC 003

DTC 003

DTC 003

--

Vehicle Speed Signal Circuit

B0540

7

B0540

--

1. Air Springs Do Not Deflate

2. Air Springs Do Not Inflate

3. Air Suspension Inflator Switch Indicator Always ON

4. Air Suspension Inflator Switch Indicator Inoperative

5. Inflator Always ON

6. Inflator Inoperative

7. Inflator Will Operate While Vehicle is in Motion

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

Connector End View Reference

Component Connector End Views

Description and Operation

Air Suspension Description and Operation

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  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.
  3. 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.
  4. Ignition ON, verify that a test lamp illuminates between the compressor B+ circuit connector X1, terminal H and ground.
  5. 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.
  6. Ignition ON, verify that a test lamp illuminates between the compressor IGN 3 circuit connector X1, terminal G and ground.
  7. 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 after completing the diagnostic procedure.

    •  Air Suspension Depressurization
    •  Automatic Level Control Air Compressor Replacement
    •  Rear Air Spring Level Sensor Calibration