Headlight and Gauge issues...

[Mobius1]

I am having a problem with the headlights, taillights, parking lamps and my gauges in my truck. About 2 months ago I was driving my truck, I traveled over a rough spot on the road, then the truck shuts off. Fuel pump is still running, no check engine lights or anything. Truck started back up like nothing happened. Drove fine for about 3 weeks. I put 1000+ miles on her since then and its been fine. Then about 1 month ago I drive the truck to work, again, truck is running fine. In the evening when I got to drive home, I have no low beams, 4 ways or turn signals. After some forum reading I found out that either the PDC or the FCM or both go bad. I figured I would try an FCM seeing as how it was just my lights that were acting up and it was the cheap(er) route. I got my new FCM in and it actually made the truck worse. Almost none of the lights worked, and my gauges would intermittently drop out. ABS, Brake, Air bag light would come on at random times. So I decided to order a PDC. Once that arrives, I installed that and it did really no difference. I had 2 codes one was for my fuel pump, which I actually pull the relay out anyway cause of my aftermarket air dog, and the other was a P1652 which is a short on the Comm Bus. I cleared both codes. Truck runs and drives fine, Still have my light problem and the gauges still dropping out at random times with the Warning Chime, Brake, ABS, Airbag light randomly coming on.

After I cleared the code the truck still exhibits this behavior, however no codes are showing up. My Auto technician friend ran the diags for that code (Test for continuity along the D25 circuit) The result was 800 ohms. 10 or less is a short. over 10 is a faulty ecm.

I also noticed too that my horn, wipers, overhead temp gauge intermittently do not work. All of these are controlled my the FCM.

So my question is, did I just get a faulty FCM and it his screwing up the gauges in my truck, or is the ECM to blame for messing up the FCM ?
Any help would be appreciated!

Thank you!

 

[Joseph Donnelly]

Check for a bad connection or wire that is broken inside the insulation.

 

[Mobius1]

Check for a bad connection or wire that is broken inside the insulation.

I didn't notice anything at first, but I will double check the harness for pinched wires etc. Thank you! forgot to add too that I cleaned connector on the ECM with a terminal cleaner and used di-electric grease on the connectors for the PDC

 

[Mobius1]

Well I double checked over everything, can't find any bad connections or pinched grounds. I tried another NEW FCM and it did pretty much the same thing. Something on my truck is NOT happy

 

[Mobius1]

I take my last post back. I found a frayed/broken ground wire on the back of thge engine that bolts to the body right next to the starter. Didn't see any damaged wires, replaced the ground cable, but still not difference. Truck is at dealers now. As much as I hate to bring it to dealers.....I don't really know what to do next

 

[Prairie Dog]

I would remove and clean (not just look at) all the grounds at the inner edge of the quarter panel in the eng compartment. Because of the way Dodge does these, they don't seem terribly important until you realize the ECM gets its negative side from one of these.

The one in the middle of this pics is for the ECM:
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Scott

 

[Mobius1]

Prairie Dog,

I had a TST there and I used that location for its ground. I will check over that location again and clean it up. It didn't appear to be too dirty though. But I will look over the cables again.

Thank you

 

[sag2]

Usually FCM or TIPM needs to be programmed with the vehicle configuration. Did you buy it new or used?

 

[Mobius1]

I bought the FCM and PDC brand new from Steve White dodge. I was under the impression that both the parts were plug and play?

 

[Mobius1]

Well truck is fixed now Turns out the ignition wiring was damaged from splicing in a turbo savor, Shift enhanser box. Truck was not receiving a 12 volt reference signal from ignition and ignition harness was repaired. Also there was a short in my L/F headlight which was causing the issue with the lights not working.

Does anybody know the part number for the ignition harness? It plugs into a connector up under the dash. IT is about a foot long. I would like to get that harness replaced.

 

[Big_Horn]

Airbag Light/ Headlights and foglights

I am looking for any ideas regarding my 3rd gen Ram 3500. I live in Washington State and I'm looking for a mechanic in the area of Tacoma or Seattle. A couple months ago I started having problems with my airbag light coming on and off. Once the airbag light was on, my turns signals would not work properly and my headlights/fog lights would go on and off. Once the airbag light was off, all functions would work properly. The problem has progressed to include the speedometer, Glow plug light staying on, Direction/temperature control gauge not working as well as my key fob working sporadically. I have tested the batteries, I've checked all major grounds on the truck, I've replaced the alternator and recently replaced the clockspring. I've also tested the Body control module and all connections leading to the BCM. Please Help!