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 |
|---|---|---|---|---|
Automatic Level Control (ALC) Inflator Solenoid Valve B+ | 1 | 1 | -- | -- |
Automatic Level Control (ALC) Inflator Solenoid Control | -- | 1 | -- | -- |
1. Automatic Level Control (ALC) Solenoid Valve Inoperative | ||||
Diagnostic Aids
Review the automatic level control (ALC) system Description and Operation. Refer to Automatic Level Control Description and Operation .
Reference Information
Schematic Reference
Automatic Level Control Schematics
Connector End View Reference
Electrical Information Reference
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Verification
Ignition ON, press the accessory inflator switch continuously for 3 seconds. This activates the ALC self test of the rear shocks. The rear of the vehicle will rise, and then hold the rear of the vehicle up for a calibrated amount of time, to check for leaks, and then lower the rear of the vehicle to trim height. The total self test time is 200 seconds.
Circuit/System Testing
- Ignition OFF, disconnect the air inflator air switch harness connector at the ALC sensor.
- Ignition ON, connect a 10A fused jumper wire between the ALC relay inflation timer relay coil control terminal 85 and the ground circuit terminal of the air inflator switch.
- Verify that a test lamp illuminates between the B+ circuit terminal A and ground.
- Ignition OFF, disconnect the ALC solenoid valve harness connector at the ALC sensor.
- Verify that a test lamp illuminates between the ALC solenoid valve B+ circuit terminal B and ground.
- Verify that a test lamp illuminates between the ALC inflator solenoid valve B+ circuit terminal B and the ALC inflator solenoid valve ground terminal A.
- If all circuits test normal, test or replace the air inflator solenoid valve.
| ⇒ | 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 ALC compressor relay. |
| ⇒ | 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 ALC solenoid valve. |
| ⇒ | If the test lamp illuminates, test or replace the ALC air inflator solenoid valve. |
| ⇒ | If the test lamp does not illuminate, test the ground circuit for open/high resistance. |
Component Testing
- Ignition OFF, disconnect the ALC solenoid valve harness connector at the automatic level control sensor.
- Test for 0-2 ohms between the signal terminal B and the low reference circuit terminal A.
| ⇒ | If not within the specified range, replace the ALC air inflator solenoid. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
