Expert: Carl Brandt - 1/24/2012

Question
I have a Lincoln Navigator 4x4 with all wheel air. My rear end does not raise. I have replaced the relay and that is functioning properly. When it calls for air the pump engages and cycles untill it shuts off but the back does not lift up. I had the vechile on Jackstands and checked the rear air bags and connectors, they are in good shape with no visible signs of failure. I stayed under for a cycle or two and  could hear solinoids engage. the front end is fine I would like to know if you can think of a way I could test the lines for leaks to the rear lines as I am limited to a set of jack stands and have no access to a lift. Or if there is something else I should check  Thanks

Answer
Greg,

The following is the inspection and verification procedure for this suspension:

Inspection and Verification

1. Note: If the door ajar indicator is illuminated when all doors, liftgate, and liftgate glass are closed, the air suspension will not work correctly. Repair door ajar indicator.

      MECHANICAL
. Restricted suspension movement          
. Excessive vehicle load          
. Cut, severed, crimped air line(s)          
. Unmounted height sensor(s)          
. Damaged rear air spring(s)          
. Damaged front air spring(s)

      ELECTRICAL
. Open fuses
. Central junction box (CJB) Fuse 6(5A), CJB Fuse 20(5A), and CJB Fuse 4(15A)
. Battery junction box (BJB) Fuse 109(50A)
. Loose, corroded, or disconnected connectors
. Air suspension switch is in the OFF position          
. Damaged solenoid valve(s)  


Visually inspect for obvious signs of mechanical and electrical damage.

  2. If the inspection reveals an obvious concern that is readily repaired, correct the concern before continuing with Inspection and Verification.
  3. If the concern remains after the inspection, use scan tool connected to the Data Link Connector (DLC) to retrieve continuous Diagnostic Trouble Codes (DTCs) and to execute On-Demand Self-Test diagnostics for the air suspension control module.

         o If the On-Demand self-test is passed and no DTCs arc retrieved, go to the Symptom Chart to continue diagnostics.
         o If DTCs are retrieved, go to Air Suspension Control Module Diagnostic Trouble Code (DTC) Index in this section.
         o If the air suspension control module cannot be accessed by scan tool, go to Pinpoint Test A.

Self-Test
Verify that the following conditions are met before running the On-Demand Self-Test.

   * All doors, liftgate, and liftgate glass must be closed.
   * The transmission is in PARK.
   * The BPP switch is not pressed during the test and the parking brake is not set.
   * The accelerator pedal is not pressed during the test.
   * The vehicle is not in 4L mode.

  1. Fulfill the pre-conditions.
  2. Install a battery charger for the On-Demand Self-Test to prevent battery drain.
  3. Run the air suspension On-Demand Self-Test.
  4. Record all listed DTCs.
  5. Retrieve stored DTCs.
  6. Troubleshoot any On-Demand Self-Test DTCs first.
  7. Retest and clear DTCs after repairs.

It would help if you purchase a repair manual from your local auto parts store for this vehicle as it would help you locate most of these components and describe the On-Demand Self-Test.

Carl