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

1, 2, 4, 6

1, 2, 4, 6

--

--

Air Suspension Compressor Assembly Ignition 3 Voltage

1, 2, 4, 6

1, 2, 4, 6

--

--

Air Suspension Compressor Assembly Ground

--

1, 2, 4, 6

--

--

Air Suspension Inflator Switch Ground

--

4, 6

--

--

Air Suspension Inflator Switch Indicator Control

4

4

3

--

Air Suspension Inflator Switch Signal

5

6

6

--

Left Rear Air Suspension Sensor Low Reference

--

DTC 002

--

--

Left Rear Air Suspension Sensor Signal

DTC 002

DTC 002

DTC 002

--

Right Rear Air Suspension Sensor Low Reference

--

DTC 003

--

--

Right Rear Air Suspension Sensor Signal

DTC 003

DTC 003

DTC 003

--

Vehicle Speed Signal

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 has the feature to utilize the air compressor as a compressed air source. When the air suspension inflator switch is activated the compressor receives a ground signal requesting compressor activation. The compressor then applies voltage to the indicator control circuit illuminating the indicator. Upon compressor activation, supplied air pressure is then diverted from the air suspension to the air supply access port.

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, activate the air suspension inflator switch. The switch indicator should illuminate and the air compressor should activate supplying air pressure to the air accessory port.

Circuit/System Testing

  1. Ignition OFF, disconnect the air suspension inflator switch harness connector X2 at the air suspension compressor assembly.
  2. If the compressor continues to run, test or replace the air suspension compressor assembly.
  3. Test for less than 2.0 ohms between the ground circuit connector X2, terminal B and ground.
  4. If greater than the specified value, test the air suspension compressor assembly ground circuit for an open/high resistance. If the circuit tests normal, replace the air suspension compressor assembly.
  5. Perform the air suspension inflator switch component test.
  6. If the air suspension inflator switch fails the component test, replace the switch.
  7. Ignition ON, connect a fused jumper between terminal A at the air suspension compressor assembly and ground. Verify that the compressor operates.
  8. If the compressor does not operate, test the IGN 3 and B+ circuits for an open/high resistance or short to ground. If all circuits test normal, test or replace the air suspension compressor assembly.
  9. Ignition ON and the fused jumper still connected, verify that a test lamp illuminates between the switch indicator control circuit terminal C and ground.
  10. If the test lamp does not illuminate, test or replace the air suspension compressor assembly.
    If the test lamp illuminates, test the indicator control circuit for an open/high resistance, short to ground, or a short to voltage. If the circuit tests normal, replace the air suspension inflator switch.

Component Testing

Air Suspension Inflator Switch

  1. Ignition OFF, disconnect the harness connector X2 at the air suspension compressor assembly.
  2. Test for infinite resistance between the signal terminal A and the ground terminal B with the switch in the OFF position.
  3. If not the specified value, replace the air suspension inflator switch.
  4. Test for less than 2 ohms between the signal terminal A and the ground terminal B with the switch in the ON position.
  5. If greater than the specified value, replace the air suspension inflator switch.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Inflator Air Switch Replacement
    •  Automatic Level Control Air Compressor Replacement
    •  Rear Air Spring Level Sensor Calibration