Pinpoint Test S: The Fog Lamps Are On Continuously
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.
- S1 MONITOR THE LCM HEADLAMP SWITCH PID
- Key in ON position.
- Enter the following diagnostic mode on the diagnostic tool: LCM DataLogger
- Monitor the LCM headlamp switch status PID (HD_LMP_SW).
- Does the headlamp switch PID indicate the fog lamp switch is active?
NOTE: Make sure the headlamp switch is in the OFF position. - S2 CHECK CIRCUIT 478 (TN/OG) FOR A SHORT TO VOLTAGE
- Key in OFF position.
- Disconnect: Fog Lamp Relay
- Key in ON position.
- Do the fog lamps continue to illuminate?
- YES : REPAIR the circuit. TEST the system for normal operation.
- NO : Go to S3.
- S3 CHECK THE FOG LAMP RELAY
- Key in OFF position.
- Carry out the fog lamp relay component test. Refer to COMPONENT TESTING article.
- Is the fog lamp relay OK?
- YES : Go to S4.
- NO : INSTALL a new fog lamp relay. TEST the system for normal operation.
- S4 CHECK CIRCUIT 1347 (DB/WH) FOR A SHORT TO VOLTAGE
- Disconnect: LCM C2145a
- Key in ON position.
- Measure the voltage between the fog lamp relay pin 1, circuit 1347 (DB/WH), harness side and ground.
- Is any voltage present?
- YES : REPAIR the circuit. TEST the system for normal operation.
- NO : Go to S7.
- S5 CHECK THE INPUT TO THE LCM
- Key in OFF position.
- Disconnect: LCM C2145b
- Measure the resistance between the LCM C2145b-11, circuit 477 (LB/BK), harness side and ground.
- Is the resistance greater than 10,000 ohms?
- S6 CHECK CIRCUIT 477 (LB/BK) FOR A SHORT TO GROUND
- Disconnect: Headlamp Switch C205a
- Measure the resistance between the LCM C2145b-11, circuit 477 (LB/BK), harness side and ground.
- Is the resistance greater than 10,000 ohms?
- YES : INSTALL a new headlamp switch. REFER to Headlamp Switch . TEST the system for normal operation.
- NO : REPAIR the circuit. TEST the system for normal operation.
- S7 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 still present?
- YES : INSTALL a new LCM. REFER to MULTIFUNCTION ELECTRONIC MODULES article. 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.