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Home >> Mercury >> 2009 >> Mariner Base, 2.5 7, AWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 146 (Interior Lighting System) >> Diagnostic Tests >> Interior Lighting >> Pinpoint Tests >> Pinpoint Test I: The Interior Lamps Are Inoperative From The Instrument Panel Dimmer Switch

Pinpoint Test I: The Interior Lamps Are Inoperative From The Instrument Panel Dimmer Switch

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, Interior Lamps for schematic and connector information.

Normal Operation 

The lighting control module (LCM) monitors the instrument panel dimmer switch status on circuit 1034 (BK/WH) to determine if the courtesy lamps are requested. Based on the instrument panel dimmer switch status, the LCM energizes the interior lamps through circuit 53 (BK/LB).

This pinpoint test is intended to diagnose the following:

PINPOINT TEST I: THE INTERIOR LAMPS ARE INOPERATIVE FROM THE INSTRUMENT PANEL DIMMER SWITCH 

  1. I1 CHECK THE INSTRUMENT PANEL DIMMER SWITCH 
    • Key in OFF position.
    • Disconnect: Instrument Panel Dimmer Switch C205b
      • Fig 1: Connecting Fused Jumper Wire
      GF0014627Courtesy of FORD MOTOR CO.
    • Connect a fused (5A) jumper wire between the instrument panel dimmer switch C205b-5, circuit 1034 (BK/WH), harness side and the instrument panel dimmer switch C205b-4, circuit 57 (BK), harness side.
    • Do the interior lamps illuminate? 
    1. YES  : INSTALL a new instrument panel dimmer switch. REFER to INSTRUMENT CLUSTER & PANEL ILLUMINATION article. TEST the system for normal operation.
    2. NO  : REMOVE the jumper wire. Go to  I2.
  2. I2 CHECK CIRCUIT 1034 (BK/WH) FOR AN OPEN 
    • Disconnect: LCM C2145b
      • Fig 2: Checking Circuit For Open
      GF0014628Courtesy of FORD MOTOR CO.
    • Measure the resistance between the LCM C2145b-3, circuit 1034 (BK/WH), harness side and the instrument panel dimmer switch C205b-5, circuit 1034 (BK/WH), harness side.
    • Is the resistance less than 5 ohms? 
    1. YES  : Go to  I3.
    2. NO  : REPAIR the circuit. TEST the system for normal operation.
  3. I3 CHECK CIRCUIT 57 (BK) FOR AN OPEN 
      Fig 3: Checking Circuit
      GF0014629Courtesy of FORD MOTOR CO.
    • Measure the resistance between the instrument panel dimmer switch C205b-4, circuit 57 (BK), harness side and ground.
    • Is the resistance less than 5 ohms? 
    1. YES  : Go to  I4.
    2. NO  : REPAIR the circuit. TEST the system for normal operation.
  4. I4 CHECK FOR CORRECT LCM OPERATION 
    • Disconnect all the LCM connectors.
    • Check for:
      • corrosion
      • damaged pins
      • pushed-out pins
    • Connect all the LCM connectors and make sure they seat correctly.
    • Operate the system and verify the concern is still present.
    • Is the concern still present? 
    1. YES  : INSTALL a new LCM. REFER to MULTIFUNCTION ELECTRONIC MODULES article. TEST the system for normal operation.
    2. NO  : The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector.
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