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

Ride Height Active Indicator Control

1

1

2

--

Instrument Panel Multifunction Switch Assembly B+

1

1

--

--

1. Compressor Inoperative

2. Compressor Always ON

Circuit Description

The air suspension control module monitors the ride height switch active light emitting diode LED indicator signal for a short to battery.

Conditions for Running the Diagnostic Fault

    •  Battery voltage is between 9-16 volts.
    •  The ignition is ON or OFF.

Conditions for Setting the Diagnostic Fault

The air suspension module senses the ride height active indicator light emitting diode LED signal circuit voltage shorted to battery, short to ground, or open.

Action Taken When the Diagnostic Fault

    • The air suspension system will be inoperative.
    • No message is displayed.

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

Scan Tool Reference

Control Module References for Scan Tool Information

Circuit Validation

Ignition ON, Observe the scan tool ERH Switch Indicator parameter while pressing/depressing the ERH Switch. The reading should change between ON/OFF and OFF/ON.

Circuit/System Testing

  1. Ignition OFF, disconnect the harness connector terminal A2 at the air suspension control module (ASCM).
  2. Ignition ON, verify that a test lamp illuminates between the instrument panel multifunction switch assembly B+ circuit Connector X1 terminal 1 and ground.
  3. 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 and the B+ circuit fuse is open, test or replace the ERH switch.
  4. Verify that a test light does not illuminate between the B+ circuit terminal A2 and the control circuit connector X1 terminal 2
  5. If the test lamp illuminates, test the control circuit for a short to ground. If the circuit tests normal, replace the air suspension control module.
  6. Remove the test lamp.
  7. Command the ERH switch indicator ON with a scan tool. Verify the scan tool ERH switch indicator parameter is ON.
  8. If not the specified value, test the control circuit for a short to voltage. If the circuit tests normal, replace the air suspension control module.
  9. Install a 3A fused jumper wire between the control circuit connector X1 terminal 2 and the connector X1 terminal 1. Command the ERH switch indicator ON with a scan tool. Verify the scan tool ERH switch indicator parameter is ON.
  10. If not the specified value, test the control circuit for an open/high resistance. If the circuit tests normal, replace the air suspension control module.
  11. If all circuits test normal, test or replace the air suspension control module.

Component Testing

  1. Ignition OFF, disconnect the harness at the ERH switch.
  2. Test for infinite resistance between the ride height active indicator control signal circuit terminal A2 and the instrument panel mutifunction assembly B+ circuit connector X1 terminal 1 with the switch in the open position. (Pressed)
  3. If not the specified value, replace the ERH Switch.
  4. Test for less than 2.0 ohms between the signal circuit terminal A2 and the instrument panel multifunction assembly B+ circuit connector X1 terminal 1 with the switch in the closed position. (Released)
  5. If greater than the specified range, replace the ERH Switch.
  6. Test for infinite resistance between each terminal and the ERH Switch housing/case.
  7. If not the specified value, replace the ERH Switch.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Rear Air Suspension Control Valve Switch Replacement
    •  Suspension Position Calibration
    •  Control Module References for Air Suspension Control Module replacement, setup and programming