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Troubleshooting light issues after re-installing a refurbished Ford/Lincoln LCM
If the LCM was fully refurbished and tested and you're still having these symptoms:
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Interior lights still stay on all the time (won't turn off)
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Turn signals not working
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One or both headlights not working properly
Chances are there is something in the vehicle at fault. The Harness that connects to the LCM uses crimp-on connectors. The conductors inside the wire jack corrode and break over time.
The multi-function switch on the steering wheel column is also wired in series with the headlight output of the LCM. If there is an issue with the harness or multi-function switch, the lighting may flicker intermittently or simply stay on.
You can use a voltmeter or lightbulb probe to quickly test the headlight output terminals on the LCM. If it's showing +12 volts at the LCM when the headlights are turned off, the issue is most likely not the LCM.
Also, for the interior lights to stay on all the time, there is a switch on the door jam that over time wears out and can't properly switch on or off. Testing and replacing this should help resolve the interior lights staying on.
Topic starter
Posted : 12/29/2023 7:26 pm
Team, I just received my LCM back and I am still experiencing the same issue/problem. The part was send in due to the signal relay staying on even when all the blinkers were off, causing the blinker alarm to go off while driving, I replaced the hazard lights and signal switch before sending the part in for repairs, please see the video as this was filmed after installing the repaired LCM, if I remove the signal fuse it stops.
Posted : 03/26/2025 11:47 pm
It's possible that there is a short in the wiring preventing the left turn signal from working properly, which is causing the left turn signal light to blink rapidly without the turn signals actually being on. Assuming it's original, you can also try to re-flash the LCM in-vehicle with FORscan to see if that helps.
Any frayed or exposed wire can cause the relay to stay energized, especially if there's poor grounding. You can also try to disconnect the turn signal and hazard switch one at a time to see if either of those two switches is causing the issue.
The LCM went through a functional test, and each function, including the hazard circuitry, turn signal lights, tested fine. If all signs still point to a faulty LCM, give us a call or email so we can assist you further.
Topic starter
Posted : 05/17/2025 7:30 pm