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Home >> Ford >> 2000 >> Taurus LX, 3.0 2, AX4N >> Repair and Diagnosis >> External Pages >> Different car >> Section 1621 (Instrument Cluster Illumination And Panel Illumination) >> Diagnostic Tests >> Instrument Cluster & Panel Illumination >> Pinpoint Tests >> Pinpoint Test A: The Control Illumination Is Inoperative

Pinpoint Test A: The Control Illumination Is Inoperative

WARNING: This page is about a different car, the 2010 Lincoln Town Car. However, it is still accessible from the selected car via links, so may be relevant.

Refer to appropriate SYSTEM WIRING DIAGRAMS article, Cluster and Panel Illumination for schematic and connector information.

Normal Operation 

The lighting control module (LCM) receives voltage from the central junction box (CJB) on circuits 54 (LG/YE) and 905 (GY/LB). Ground is provided by circuit 676 (PK/OG). When the headlamp switch is in the PARKING LAMPS or HEADLAMPS ON positions, the LCM generates a variable pulse-width modulated (PWM) voltage which is distributed to the dimmable components on circuit 484 (OG/BK). Light intensity is adjusted by rotating the instrument panel dimmer switch.

This pinpoint test is intended to diagnose the following:

PINPOINT TEST A: THE CONTROL ILLUMINATION IS INOPERATIVE 

NOTE: Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may damage the connector.
  1. A1 CHECK CIRCUIT 905 (GY/LB) FOR AN OPEN 
    • Key in OFF position.
    • Disconnect: LCM C2145c
      • Fig 1: Checking Circuit For An Open
      GF0018953Courtesy of FORD MOTOR CO.
    • Measure the voltage between the LCM C2145c-17, circuit 905 (GY/LB), harness side and ground.
    • Is the voltage greater than 10 volts? 
    1. YES  : Go to  A2.
    2. NO  : VERIFY the CJB fuse 21 (10A) is OK. If OK, REPAIR the circuit. TEST the system for normal operation.
  2. A2 CHECK CIRCUIT 676 (PK/OG) FOR AN OPEN 
      Fig 2: Checking Circuit For An Open
      GF0018954Courtesy of FORD MOTOR CO.
    • Measure the resistance between the LCM C2145a-11, circuit 676 (PK/OG), harness side and ground; and between the LCM C2145c-7, circuit 676 (PK/OG), harness side and ground.
    • Are the resistances less than 5 ohms? 
    1. YES  : Go to  A3.
    2. NO  : REPAIR the circuit in question. TEST the system for normal operation.
  3. A3 CHECK FOR CORRECT LCM OPERATION 
    • Key in OFF position.
    • 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 is 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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