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Home >> Mercury >> 2009 >> Mariner Base, 2.5 7, AWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 139 (Electronic Suspension - Vehicle Dynamic Suspension System) >> Diagnostic Tests >> Vehicle Dynamic Suspension >> Pinpoint Tests >> Pinpoint Test I: The Air Compressor Runs Continuously with the Ignition Switch in the OFF Position and No DTCs Are Set

Pinpoint Test I: The Air Compressor Runs Continuously with the Ignition Switch in the OFF Position and No DTCs Are Set

WARNING: This page is about a different car, the 2009 Mercury Grand Marquis and 2009 Ford Crown Victoria. However, it is still accessible from the selected car via links, so may be relevant.

Refer to appropriate SYSTEM WIRING DIAGRAMS article, Vehicle Dynamic Suspension for schematic and connector information.

Normal Operation 

With the air suspension switch and the ignition switch both in the ON position, the vehicle dynamics module (VDM) uses input from the suspension height sensor to determine if vehicle payload has changed enough to warrant the adjustment of the rear suspension. If an adjustment is necessary, the VDM will open the air spring solenoids and activate the air compressor to inflate the air springs and raise the rear suspension. To deflate the air springs and lower the rear suspension, the VDM will open the air spring solenoids and activate the vent solenoid.

With the air suspension switch in the OFF position, the VDM will ignore height sensor input and not adjust the rear suspension. When the ignition switch is placed in the OFF position, the VDM will remain powered for approximately 60 minutes to allow the system to adjust the rear suspension due to changes in vehicle payload. Once the 60 minutes has elapsed, the VDM will depower and will ignore any height sensor input until the ignition switch is placed in the ON position.

This pinpoint test is intended to diagnose the following:

PINPOINT TEST I: THE AIR COMPRESSOR RUNS CONTINUOUSLY WITH THE IGNITION SWITCH IN THE OFF POSITION AND NO DTCs ARE SET 

  1. I1 CHECK FOR CORRECT VDM OPERATION 
    • Key in OFF position.
    • Toggle the air suspension switch to the OFF position.
    • Verify the air compressor no longer runs 60 minutes after the ignition switch is placed in the OFF position.
    • Does the air compressor continue running after the 60 minutes elapse? 
    1. YES  : Go to  I2.
    2. NO  : The system is functioning correctly at this time. EXPLAIN the 60 minute time out to the customer.
  2. I2 ISOLATE THE VDM 
    • Disconnect: VDM C2131a
    • Does the air compressor continue to run? 
    1. YES  : Go to  I3.
    2. NO  : INSTALL a new VDM. REFER to Vehicle Dynamics Module (VDM) . TEST the system for normal operation.
  3. I3 ISOLATE THE AIR COMPRESSOR RELAY 
    • Disconnect: Air Compressor Relay
    • Does the air compressor continue to run? 
    1. YES  : Go to  I4.
    2. NO  : INSTALL a new relay. TEST the system for normal operation.
  4. I4 CHECK THE AIR COMPRESSOR ACTUATION CIRCUIT FOR A SHORT TO VOLTAGE 
    • Disconnect: Air Compressor C1179
      • Fig 1: Checking Circuit For Voltage
      GF0013888Courtesy of FORD MOTOR CO.
    • Measure the voltage between air compressor C1179-2, circuit 538 (GY/RD), harness side and ground.
    • Is any voltage present? 
    1. YES  : REPAIR circuit 538 (GY/RD). TEST the system for normal operation.
    2. NO  : INSTALL a new air compressor assembly. REFER to Air Suspension Compressor . TEST the system for normal operation.
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