System Operational Check

Turning the ignition switch from the Run to Off position clears all memory which is stored in the control module. Therefore, a test lamp (used during the actual diagnostic procedure) may not immediately indicate a failure when the ignition switch is returned to the Run position.
When charging the battery (battery is discharged when conducting the actual diagnostic procedure), the ignition switch must first be in the Off position or serious damage to the air compressor relay or motor may occur. However, use of a battery charger while performing the diagnostic tests (described further on in this section) is acceptable. Set the battery charger to a rate to maintain, but not damage, the vehicle battery. The following diagnostic test procedures are guides that will lead to the most probable causes of automatic leveling system problems. It is important to accurately identify the problem or condition before selecting and using the appropriate diagnosis procedures and charts described further on. Whenever conducting diagnosis procedures, always cycle the ignition ON then Off, before starting the actual diagnosis or test procedure to ensure vent solenoid and compressor reset ON times.

Fig. 5 Diagnosis Selection Chart:

1. Set vehicle trim height as described in ADJUSTMENT PROCEDURES at recommended curb height and measure from known level floor (surface).
2. Briefly start and operate engine.
3. Apply approximately 300-350 lbs. of load to rear of vehicle and note the following:
a. There should be a 7-13 second time delay before the compressor turns ON and rear of vehicle starts to rise.
b. Vehicle should rise to within 1/2 inch of measurement taken in step 1 by the time the compressor shuts off. If vehicle does not rise, refer to diagnosis selection chart, Fig. 5. Failure of the vehicle to return to within 1/2 inch of unloaded dimension can be caused by unusual heavy loading in the luggage compartment which exceeds the system capacity. If this type of loading is encountered, remove it and repeat test.
4. Remove load applied in step 3, and note the following:
a. There should be a 7-13 second time delay before vehicle starts to lower.
b. Vehicle should lower to within approximately 1/2 inch of measurement taken in step 1 in less than one minute. If vehicle does not lower, refer to the diagnosis selection chart.