2004 grand marquis LCM already replaced under recall :()
Hello Scotty we have a 2004 Grand Marquis with 150,000 miles. The LCM light module was recalled several years ago and was fixed by another owner but now the back lights are not coming on (the running lights come on) do you think the LCM would go out AGAIN?? also, how often are you supposed to change the plugs and wires? We live in Augusta, GA
Edit: no the running lights in the back don't come on (but the break lights and other running lights do work fine)
The way you could test this is by bypassing the LCM and seeing if the tail lights illuminate.
The connectors on the back of the LCM look like this.
The White connector on top is called C2145b. I added some text to show the tail light circuit.
Here's the pinout of the C2145b connection ON The LCM.
The pinout says that power to the tail lights comes into the LCM on circuit 195 (TN/WH wire) on pin 12. When the tail light relay inside of the LCM is energized power goes out on circuit 14 (BN wire) from pin 4 to the tail lights.
The wiring connector side is the mirror image. So those pins on the connector look like this.
To troubleshoot if this is either a power/wiring issue to the tail lights or a faulty LCM you can just disconnect LCM connector C2145b and use a paperclip to jump the (connector side) 3rd pin from the right on top with the 5th pin from the right on bottom.
If the tail lights illuminate then it's likely a faulty LCM.
If the tail lights don't illuminate then it isn't the LCM. It's either the light switch or the power feed (to pin 12) or the wiring to the tail lights from pin 4.
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