If the compressor is coming on, it is attempting to inflate the suspension. Raise the rear of the vehicle and inspect the air lines for leaks. Also inspect the air springs. Use of a spray bottle with a soapy water mixture is helpful in finding leaks. If no leaks are found, you may have a problem with the compressor check valve. Refer to bulletin below.
02-03-99-001: Rear of Vehicle Sits Low, Electronic Controlled Air Suspension (ECAS) Compressor Runs - Will Not Lift Rear to Operating Height (Repair ECAS Compressor with Check Valve Service Kit) - (Jun 17, 2002)
Some customers may comment that the rear of the vehicle sits low and will not return to normal operating height. The customer may be able to hear the ECAS compressor running.
The compressor check valve may be sticking in the compressor housing, not allowing the ECAS compressor to build pressure and raise the rear of the vehicle.
Important: Do not replace ECAS compressor P/Ns 15094346 or 15745306.
Follow the service procedure below to correct this condition.
Caution: A sudden release of pressure may cause personal injury or damage to the vehicle. The air suspension system is under pressure until the air supply lines are disconnected. Use the following precautions when servicing the air suspension system:
Important: DO NOT allow any foreign material to fall into the compressor head.
Tighten Tighten the cylinder head screws (1) to 5 N·m(44 lb in).
Important: Ensure that the color on the air supply lines match the color on the air spring compressor for reassembly. The right side line is clear and the left side line is black. Right and left is also indicated on the compressor.
Tighten Tighten the air supply line fittings to 2.25 N·m (18.5 lb in).
Tighten Tighten the air spring compressor to frame mounting bolts to 25 N·m(18 lb ft).
Important: Inspect the rear air springs for proper seating before inflating the rear air springs.
ECAS Compressor Service Kit