As long as I've had the 2003 Dodge Ram 2500, the ABS and brake lights would come on intermittently. The would sometimes turn on while driving, but would only turn off with a shutoff and restart. This became more and more common until I couldn't turn it off. I went to Advance and they couldn't communicate with the ABS module. So a few days later I played leap frog with the relays. This fixed it for a while. Then it started happening again. Saturday, I cranked it up and the lights came on again, and I had no speedometer, and no horn, but the truck shifted normally; I had to speed check by the tachometer. I pulled over and swapped relays in pairs to isolate a bad relay, but this fixed nothing. So yesterday I pulled them all out and tested each with a 12 volt battery, jumpers and a 12 volt LED to make sure power was getting switched. They all passed in both normally open and normally closed positions. So I reinstalled them and turned the truck on, and the lights were still on. So I pulled the connectors to the ABS module and cleaned them, then reconnected them. Then I replaced the speed sensor on the axle. This morning, I cranked it up to let it warm up, and noticed my brake lights (but not the CHMSL) were burning for no reason. Pressing the brake pedal did nothing to the lights. I headed to work, and for kicks I tried the horn. The engine bogged down and tried to stall! When I did this at a stop light, the engine actually shut off. So once I got to the job site, I had my Dad press the horn as I pulled relays out one by one, because I thought surely the relay was bad. Once I found it, I noticed my brake lights were burning, even with the truck off. I went to Advance and they pulled these codes:

ABS 96 Over/Under voltage
ABS 84 Mismatched Vehicle ID
P0500 Vehicle Speed Sensor A
P0720 Output Shaft Speed Sensor Circuit

So, once I got home, I cleared the codes and unhooked the battery. I will leave it overnight and hook it back up in the morning, but this has me stumped. What do I do?

 

as for the brake lights.. the brake light switch is bad... very common... brake lights staying ON... mine did this last year.. on a long trip. so NO cruise control.. for a day.

do a search on electronic fuse box... another common problem... TIP something.

 

I hooked the battery back up and turned the key to "run". Still the ABS and Brake lights were on. I cranked it up and tried the horn; I had no horn, but the engine didn't care. I asked my brother to turn the truck around and put it on the apron so I could diagnose my Death Wobble problem, and noticed the brake lights were correctly functional. There was still no speedometer though. But he informed me that today, using the electric defoggers did the same thing today that pressing my horn did yesterday. I called my dealership and he said it sounded like the Body Controller because all these things go through that. Anyone's thoughts?

 

On a 2003, its a Power Dist Module, or Front Control Module.


Tipm didn't come out until 2006, when Canbus communications were introduced.


Fcm has given many, much problems. Usually best way is to pull it all apart, its under the fuse/relay block, look for corroded runways and the like

 

Are you sure? Look, I have a very limited income but I need my rig for my business. I was planning on dropping it off at the dealership to spend coin I can't really spend, but I will have a look tomorrow when I get home. By the by, how do you fix "corroded runways and the like"? (no offence)

 

Thank You, I did not know all the year changes....

so I have the FCM... and I know my trailer light problems is the FCM...

as for the damage.. there is a post here on how to fix some of the problems... involves Soldering on circuit boards... fixing or replacing board traces... if someone does post it.. I am going to bookmark it. for later..

 

Yup,
Just as Chuck said, it does first require inspection of the PC board, if the runways are corroded, they'll have to be cleaned and resoldered or a piece of wire soldered in completing the runway.


Yes, I'm sure. I have the FCM for my trucks both of which are a 2005, the last of the old comm bus. That's why you can't have the radio play after you turn off the ignition until you open the drivers door, the later years, this could be done, also, you have relays and fuses in your fuse box, the Totally Integrated Power Distribution module does all these electronically.
Checking this stuff is just a first step, but many others with 2003 and 4's have already gone down this road, some it was a simple fix, others were so bad, the brain box had to be replaced. I have 205K Michigan salt covered miles on mine and haven't had any problems with it, but, that could change.
I understand about bucks, I try to avoid a dealership at all cost, its always a last resort

 

Okay, sorry so late for an update, but my Dad had a universal joint that desperately needed replacement. Anyways, the dealership called me today and said that the reason my truck was freaking out was because of a failing Power Distribution Module. He also said the reason my engine died every time I pressed the horn (and later defoggers) was because my Ignition Switch was shot (which I already knew, but didn't associate with my problems). All in all, this will set me back $1,500. (right now, life sucks.....) Hope this helps future viewers....