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

WARNING: This page is about a different car, the 2006 Mercury Grand Marquis and 2006 Ford Crown Victoria. However, it is still accessible from the selected car via links, so may be relevant.

CAUTION: Use the correct probe adaptor(s) when making measurements. Failure to use the correct probe adaptor(s) may damage the connector.

C1 CHECK THE LCM FOR VOLTAGE
- Key in OFF position.
- Disconnect: LCM C2145a.
- Key in ON position.
- Measure the voltage between LCM C2145a-13, circuit 221 (OG/WH), harness side and ground.
  
  Fig 1: Measuring Voltage Between LCM C2145a-13, Circuit 221 (OG/WH) And Ground
  Courtesy of FORD MOTOR CO.
- Is the voltages greater than 10 volts?
Yes : GO to C2.

No : VERIFY the CJB fuse 8 (10A) is OK. If OK, REPAIR the circuit. CLEAR the diagnostic trouble codes (DTCs). REPEAT the self-test.
C2 CHECK LCM GROUND CIRCUITS FOR AN OPEN
- Key in OFF position.
- Disconnect: LCM C2145c.
- Measure the resistance between LCM C2145a-11, circuit 676 (PK/OG), harness side and ground; and C2145c-7, circuit 676 (PK/OG), harness side and ground.
  
  Fig 2: Measuring Resistance Between LCM C2145A-11 And Ground And C2145C-7 And Ground
  Courtesy of FORD MOTOR CO.
- Are the resistances less than 5 ohms?
Yes : REFER to MODULE COMMUNICATIONS NETWORK to diagnose the communication network.

No : REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test.