Leak Checks

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.

1. Repeat Residual Air Check steps 1, 2, 3 and 4 and allow the system to fill, until pressure gauge reads 70-100 psi. If the compressor is permitted to operate until it reaches its maximum output pressure, the vent solenoid valve will function as the relief valve. The resulting leak down when compressor shuts off will indicate a false air leak.
2. With load still applied to the vehicle, disconnect wire harness connector from the control module and then remove applied load. Vehicle rear should rise. Cycle ignition switch to Off position.
3. Observe if pressure leaks down or holds steady (wait approximately 15 minutes) and note the following:
a. If system will not inflate beyond 50 psi, a severe leak is indicated. Check for pinched pressure line between compressor and shocks.
b. If pressure is maintained steady, perform the diagnosis procedures.
4. Connect wire harness connector to module.
5. Turn ignition switch from Off to Run position and allow air to exhaust (vehicle lowers).
6. After attachment of the pressure line to the dryer, repeat Residual Air Check steps 2, 3 and 4 to ensure system air pressure is within the shocks.