Pinpoint Test D: No Communication With The Lighting Control Module (LCM)

WARNING: This page is about a different car, the 2005 Lincoln Town Car. However, it is still accessible from the selected car via links, so may be relevant.

D1 CHECK CIRCUITS 640 (RD/YE), 221 (OG/WH), AND 964 (DB/LG) FOR VOLTAGE

Key in OFF position.
Disconnect: LCM C2145a and C2145b.
Key in ON position.

Measure the voltage between the LCM harness side and ground using the following chart.

LCM CONNECTOR-PIN SPECIFICATION

LCM Connector-Pin	Circuit
C2145a-4	640 (RD/YE)
C2145a-12	221 (OG/WH)
C2145b-6	964 (DB/LG)

Fig 1: Measuring Voltage Between LCM Harness Side And Ground

Courtesy of FORD MOTOR CO.

Are the voltages greater than 10 volts?

Yes : GO to D2.
No : REPAIR the circuit(s) in question. REPEAT the self-test.

D2 CHECK CIRCUIT 676 (PK/OG) FOR AN OPEN
- Disconnect: LCM C2145c.
- Measure the resistance between LCM C2145a pin 14, circuit 676 (PK/OG), harness side and ground; and between LCM C2145c pin 7, circuit 676 (PK/OG), harness side and ground.
  
  Fig 2: Measuring Resistance Between LCM C2145a Pin 14, Circuit 676 (PK/OG), Harness Side And Ground; And Between LCM C2145c Pin 7, Circuit 676 (PK/OG), Harness Side And Ground
  Courtesy of FORD MOTOR CO.
- Is the resistance less than 5 ohms?
- Yes : Refer to MODULE COMMUNICATIONS NETWORK to continue diagnosis of the communication network.
- No : REPAIR the circuit(s) in question. REPEAT the self-test.