New member here. My 2004 1500 5.7L Hemi has picked up a glitch that is becoming a real pain. While sitting in the driveway the lights will come on and turn themselves off with no one in the truck. It has taken the battery down many times now and I have had to disconnect the battery to keep it from draining it overnight. I replaced the brake paddle switch with no improvement. I am now wondering if it is the BCM (assuming that my year truck has one), and if so, where is it located and can I replace it with a used one that does not need to be reprogrammed. I have seen videos of later models that have a very complicated procedure involving a laptop and WIFI in order to reprogram, but I get the feeling that my truck would be much simpler. Any help or info would be appreciated.

 

Yup. Brake lights are controlled by the Front control module, which I think is part of the Power distribution module....... Likely an integrated circuit, and thus, not easily repairable.

 

Thanks for that. Figured as much. Do you know where the FCM is located on the truck and whether I can just buy one from another vehicle and install it without having to reprogram it? Is it located next to the fuse box?

 

Part of the power distribution center under the hood, no idea if it's a replaceable module, or if you need the whole TIPM......

 

OK, so I relaced the FCM with a used one from Ebay and I still have the issue. Not only does the brake lights come on, but they also go off by themselves. This is mind boggling to me that replacing the FCM doesn't fix the issue. What else could possibly be doing this? A unique aspect of the issue is that ONLY the left and right brake lights come on and off, not the red light behind the top of the cab.

Anyone else have anything like this going on with their truck? By the way, I have always had another crazy thing with this truck. When I first start it up, the oil pressure gauge doesn't work and an idiot light comes on that reads check gauges. If I turn the ignition off and restart it, the gauge ALWAYS comes on. Never the first time, always the second time. Crazy.

 

The brake light on the back of the cab is powered directly from the brake switch. The ones in the back go thru the fcm. There is a feed from the brake switch that clues in the instrument cluster, that you are stepping on the pedal.... I would *assume* that circuit is 12 volts, as it does power a bulb or three..... the wire also runs off the page, with a reference, but, I don't seem to have the second page available..... So, not sure what else it is doing......

The cluster, I assume.... clues in the FCM via the pci bus to turn on the brake lights. Wonder if a mean enough scanner would be able to read that little bit of data.....

 

Thanks for that info. Makes sense now that the cab light would be different. I have decided to go the brute force route and disconnect the battery after use if it is not going to be used in a bit. The truck sits a lot so I can get away with that. I do feel snake bit though.

 

Did you replace the brake light switch on the pedal?

 

I think that was the first thing he did.