Pinpoint Test B: One Low Beam Headlamp Is Inoperative
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.
- B1 CHECK CIRCUIT 57 (BK) FOR AN OPEN
- Key in OFF position.
- Disconnect: Inoperative Headlamp.
- Measure the resistance between the LH headlamp C1021-2, circuit 57 (BK), harness side and ground; or between the RH headlamp C1041-2, circuit 57 (BK), harness side and ground.
- Is the resistance less than 5 ohms?
Yes : GO to B2.
No : REPAIR the circuit. TEST the system for normal operation.
- B2 CHECK CIRCUIT 1055 (WH/LG) OR CIRCUIT 1056 (DB/LG) FOR AN OPEN
- Disconnect: LCM C2145d (LH Headlamp) or C2145c (RH Headlamp).
- Measure the voltage between the LCM C2145d-21 (LH low beam), circuit 1055 (WH/LG), harness side and ground; or between the LCM C2145c-19 (RH low beam), circuit 1056 (DB/LG), harness side and ground.
- Is the voltage greater than 10 volts?
Yes : GO to B3.
No : VERIFY the CJB fuse 19 (10A) or fuse 21 (10A) is OK. If OK, REPAIR the circuit in question. TEST the system for normal operation.
- B3 CHECK THE HEADLAMP VOLTAGE SUPPLY CIRCUIT FOR AN OPEN OR SHORT TO GROUND
- Measure the resistance between the inoperative headlamp, harness side and the LCM, harness side; and between the inoperative headlamp, harness side and ground as follows:HEADLAMP AND LCM CONNECTOR AND CIRCUITS
Inoperative Headlamp Headlamp Connector-Pin LCM Connector-Pin Circuit LH C1021-1 C2145d-22 160 (DB/WH) RH C1041-1 C2145c-20 161 (DG/OG) - Is the resistance less than 5 ohms between the headlamp and the LCM, and greater than 10,000 ohms between the headlamp and ground?
Yes : GO to B4.
No : REPAIR the circuit in question. TEST the system for normal operation.
- Measure the resistance between the inoperative headlamp, harness side and the LCM, harness side; and between the inoperative headlamp, harness side and ground as follows:
- B4 CHECK FOR CORRECT LCM OPERATION
- Disconnect all the LCM connectors.
- Check for:
- corrosion
- 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?
Yes : INSTALL a new LCM. REFER to MULTIFUNCTION ELECTRONIC MODULES . TEST the system for normal operation.
No : The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector.