Electricial Gremlins

syntheticracer · June 10, 2004

I have a 2002 2500HD 6L complete w/ towing package. I have not had any problems until last week when I was coming home from a race. I was on the road for 2 hours and came to my first stop light. While I was sitting there waiting for the light to change, the electrical door locks started pulsing (approx 5 times) and the engine wanted to stall. I gave it some gas and the light turned green. I thought that this was strange, but it only happened one time in 2.5 years.

Tonight, I hooked up our horse trailer (w/ elect trailer brakes) and was going down the road when all of the sudden, the trailer brakes locked up and there we sat. Luckily we were not on the main highway yet. The only way I could get out of this situation was to unhook the trailer plug (7 pin). When I tried to rehook the electrical, the same situation occurred. We ended up driving back home with no trailer brakes/lights.

I also noticed that the dash lights and radio display was flickering (bright to dim and back again)

I am going to take it to the dealer tomorrow, but our dealer is terrible and the only way to get them to fix anything is to do the research yourself and tell them what is wrong and what needs to be fixed. I had to take it back to the dealer 5 times to get the steering column rattle resolved (there was a bulletin on this that they could not seem to locate).

Any help or information would be greatly appreciated.

Thanks,

Chris

citydriver · June 10, 2004

This is just a guess,but it sounds like you may have a short,I would start by checking the wiring for your trailer brake controler..depending on where its tied into the brake light circuit,if they tied into it from the drivers kickpanel,the trucks wiring harness may have been rubbing against a ground and finally wore through the insulation..I've seen this B4...or maybe your 7-way socket on the truck may have an internal short,or a case of the greenies(corrosion) which would explain the lights dimming..I would also suggest that you inspect the pigtail connector on the trailer to make sure its in good condition,the plastic tends to dry out and weaken over time...just a few things to check..good luck

snoman · June 10, 2004

No, I think he has a bad ground and that would explain the strange problems he is having as it seeks a new return circuit of some kind.

seadoons · June 10, 2004

This is going to sound like it is probably not the problem, but take your truck to Wal-Mart and have the battery tested. My dad's old truck (he used to have a 2000 GMC) started freaking out - the electrical system went nuts. Dash lights flashing on and off, the truck started running weird, etc., etc. He took it in, and all it was was a bad battery!

frdfandc · June 10, 2004

I know this might not pertain, but when I worked for a Ford dealer a few years back, I saw several trucks with a similar electrical problem. Ended up being the trailer plug harness on the truck. Corrosion had set in and was causing all kinds of electrical gremlins. I would start with the trailer harness's first then go from there.

AZ-Z71 · June 10, 2004

I would say it was either the battery or the plug on the truck. Have the battery tested first. You can find any autopart store that will check it for free. It could be that the battery voltage is low and that the autobrake controller detected the low voltage which would have signaled the full lock of the trailer brake system.

Yes I also have seen weird symptoms as described with the locks when a battery has shorted itself and some weirdness in the guages.

Second would be the plug end on you truck. Could have gotten some moisture in there and/or corroded. I've seen this before with trucks that trailer boats. Someone backs the trailer too far into the water and the water gets into the connection.

snoman · June 10, 2004

I would not bother, your simptoms match a bad or floating ground perfectly. You would be wasting your time with battery on this one. I have seen bad grounds do some real unbelievable stuff in cars!

zorrro · June 11, 2004

I'm on board with the ground vote. I love electricity; it is straightforward, logical and predictable. Whenever it seems like its not, the problem seems to lie in the ground. If your truck is using the factory towing harness and fuses etc, it is pretty safe from any kind of short circuit. Real short circuits create high current draw. High current draw blows fuses. This is real nice as those fused things quit working, you find your way to the fuse, isolate the short (or keep replacing fuses), fix the short and go on all clam happy. Brake lights draw fairly high current for a bad ground to support. At stop lights when your brake lights are usually on, the electrons may find an easier path to ground through your tail lights, or through your head lights or through your electric door locks if the ground on your trailer is crummy.

I recently fixed a 10-year old snowmobile trailer that was getting freaky. The trailer body looked like a one-piece unit, it wasn't. It was two sections bolted together, rust built-up between the two sections and the trailer body wouldn't support the flow of much current. When the lights were on you could actually measure a voltage drop across the trailer body from tongue to tail (and across that union!). A short piece of wire across that union fixed the problem. Look for bad grounds..........