For 1990-2009 cars

Symptom | Diagnostic Procedure
--- | ---
The inflator switch does not activate the compressor motor. | Refer to chart 1 in Electrical Diagnosis.
The inflator switch activates the compressor motor, but high pressure air is not available at the inflator fill valve. | Refer to Air Compressor Leak Test and chart 2 in Electrical Diagnosis.
The inflator switch activates the compressor motor, but the switch will not turn the compressor motor off. | Refer to chart 3 in Electrical Diagnosis.
The auto level control air compressor motor does not turn on in order to raise the rear of the vehicle (regardless of the weight added to the vehicle), the inflator switch operates normally. | Refer to chart 4 in Electrical Diagnosis.
The auto level control air compressor motor does not turn on in order to raise the rear of the vehicle unless excessive weight is added to the vehicle. | Refer to Automatic Level Control Sensor Adjustment .
The ALC system does not exhaust to the lower rear of the vehicle and the inflator switch operates normally. | Refer to Air Compressor Leak Test and chart 5 in Electrical Diagnosis.
The auto level control air compressor motor runs frequently, continuously, or a maximum run time (5½ minutes). | Refer to Air Compressor Leak Test and chart 6 in Electrical Diagnosis.
The Air Replenishment Cycle is not functioning as described above and the inflator system operates normally. |
Repeated incidents of a blown ALC system fuse. | Refer to chart 7 in Electrical Diagnosis.