Need help from the brain trust that is the "Beeb" - GMC Sierra 3500HD blinker issue

Cuz it needed the money

Duh

 

Stories from the That Really Happened files…

Yesterday I spent a couple hours helping a friend diagnose a parasitic draw in a 2004 Yukon. Guarandamnteed the battery would be dead every morning.

Disconnected the hyooj terminal block off the underhood fuse panel and the draw disappeared.

Amp clamp wouldn’t register any draw so we ended up using a test light and manually connected every. single. terminal one at a time to see what was pulling load.

OnStar module was one.

Transfer case control module was another.

Disconnected the OnStar, cuz, you know, fuck OnStar, and tossed a used TCCM on to test.

This morning the truck had a charged battery and started right up.

That’s how much of a cunt these things can be. He had to walk away from the troubleshooting before he asked me for help because he was ready to test some Tannerite with it.

 

That is correct.... but many times the symptom does not repeat.

I did not say that was the final solution...it`s a beginning of diagnostics. And if if it does not repeat, there is no further checking until the problem is active. If, the fuse is open....

 

Fuse is good. Will continue to troubleshoot the wiring this weekend.

 

Was there any maintenance recently done? Or anything happen to the truck unrelated? Anything aftermarket wired in? Aftermarket taillights or bulbs?

 

Nope, standard use which is very little, bone stock, no mods. The truck sits a lot as I work from home. Have owned it since 2018 and only put 30k miles on it.

At this point, I have to think its a corroded connection or something wiring related. I will be digging in to trace the wires until I find the source of the issue. Fun time I am sure...

 

As a dyed in the wool do-it-yerself’er, it pains me to say this but time/expense might best be mitigated by spending a bit of coin at the stealership, they can plug in and test the circuits with a fuckload more efficiency.

 

Maybe mice made nest somewhere in there and was pissed wire passing through his house.

 

Id drop the spare tire, and crawl under the box. That wiring is pretty open back there. Clean up all the grounds, and look for broken wires. Id put my money on a bad ground, or a dirty plug.

 

You have a point and im getting close to this

This did happen to my brothers truck that sits as well. His is in a barn though and mine is out in the open with nothing around it sitting on a gravel driveway. I do use it at least once a week for short hardware store, go shootin', etc, trips and have not seen any evidence of mice but wouldn't hurt to further investigate.

That's my next step, the tail light harness junction box is up just next to the spare making it difficult to access. Dropping the spare will make it easier for sure. Looks like I am getting dirt in my eyes today laying on my back under the truck! Where did I put those safety goggles?!!?

 

Are there any codes? This circuit involves the BCM.

Not sure how familiar you are with automotive; do you have a wiring diagram?

If you are not, you might consider a competent technician or as said, the dealer.

 

Remove the Tee at the hitch plug and see if the issue goes away.

 

Solved, wire was broken in the bulb connection that was difficult to locate. New sub harness, issue resolved.

 

Glad you figured it out. Thank you for following up, that you found the cure, and what it was. Many times forum people ask for help, fix it, then never say what the outcome was. This helps others, with similar problems. Ski

 

What about the side mirror blinker? I bought aftermarket led side mirror blinkers and it failed after 4 months. Causing the fast blink and I couldnt find it at first.

Thats all I got for ya!

 

My turn.

2019 RAM 2500. All the signals and brake lights work as they should. When I hook up any trailer, the driver's side turn signal doesn't flash on the trailer. Again everything works as it should, except the driver's side turn signal. Brake light, running light, etc all work. But no blinker.

 

Sounds like a wiring difference on the trailer. Sometimes they wired differently. I went to a trailer/RV place and they had a tester to plug into my cannon plug and could tell me the wiring compatibility.

Or could be a bad connection in the plug. Clean and die-electric grease.

 

I'm dealing with a trailer light issue now but I know its the truck as it does the same thing on 2 different trailers. I get very weak running lights. Brake lights, blinkers hazards all work but the running lights are very dim. I believe I may have a bad ground. My next step is I am just going to replace the trailer light plug sub harness on the truck. Its well worn and has been pull out of its normal secure position.

 

Why do GM trucks and Toyotas continually have a bulb out? With GM it is usually the left. And many times it is a new or nearly new vehicle. I'm not trying to start a brand war, but it is just something I notice alot on the road.

 

You mean the DRL's? On GM trucks is because the voltage spikes take the bulbs out. Usually caused by the socket getting rusty. Pull bulbs, put dielectric grease in the socket and put bulb back in. Stops the issue.