Jamie Clay

So I've been trying to sort out an electrical problem I'm having with my Uplander. While driving, random dash warning lights cycle on and off. ABS, Traction, Tire Pressure and so on. It seems to behave for long stretches then starts the cycles through the warning lights. Other problems that occur are the battery going dead if left undriven for more than a week , the Cruise Control sporadically working and the turn signals not clicking correctly (I have to assume they're flashing the same way)

I swore one time I found a video talking about there being a faulty harness plug under the passenger seat. That it gets corroded and this results in a lot of electrical issues But now I can't find it and was hoping someone else has a link to it.

Anyone familiar with this?

Thanks,

Jamie

12three

i would check alldata or chilton... probably a faster answer

Jamie Clay

You mean the manuals? I do have good manuals but they don't list this sort of problem. As I said, I could have sworn there was a video talking about this problem.

Oh well, thank you for your reply

kevinkpk

Google it in youtube. Does sound like a connection problem.

vinman

Yup , I read about that and it usually points to where the wires go through the firewall across a 2 piece connector that is split in half on either side of the firewall , it's a common problem with a lot of mini vans and pickups

Over the years as I've read about this problem on various forums I took the time to email people and ask them a question to answer my own conducted poll and I've come to a conclusion

I've come to the conclusion that there is a common denominator in the majority of the times where people that have these symptoms/problems with their Uplanders, Montanas , Astros Safaris etc , leave their vans outdoors unprotected in the rain and snow for extended periods of time

The water will run down the firewall and create all kinds of havoc on that connector corroding the wires and connector pins on that plug
The water might also eventually enter under the windshield gasket and drip inside the vehicle under the dash onto electronic modules creating for example the dreaded Pass Lock VATS security system screwups , as well as all sorts of other stuff under the dash

Never had any electrical issues on my '08 Uplander , '03 Astro , '96 Dually , '86 1 Ton Square Body or '82 fullsize Vandura and my other pile of Old School GMs which I still own and use since they where new , probably because they've always been indoors away from rain and snow up here in northern Ontario Canada

Cheers ...... Vinny

Jamie Clay

Thanks - yeah, it looks like I need to become familiar with all the car's harness plugs to see where the problem is. Oh well, what fun.

Thanks for the reply - if I find anything, I'll be sure to post the solution here.

12three

yeah, they have wiring diagrams on alldata and chilton. public library probably has online access to them.
i get traction control lights every blue moon, i think they have always been related to wheel bearing probs in my case. i replaced the front bearings and it virtually disappeared. i got abs and traction control lights recently after i replaced a front caliper... it hasnt come back either, so i havent dug too deep electrically in order to help. the only mentions of the issue you describe that i have seen were actually by you...
i have heard of water intrusion via firewall on astros like the guy above mentioned. i wouldnt be shocked if similar issues were common on uplanders. floorboards are universally rusted out on every junkyard uplander montana relay terraza i have ever seen in the midwest. and ive personally seen water sitting on my rusted out floors too. i know theres wires under the drivers side floor. not sure what they are or where they go, but im sure they are on the diagrams.

vinman

Thank you for the input , further proof that if left outdoors water will wreak havoc on the electrical system
Removing the 2 front seats and lifting the carpet might reveal wires sitting in water and a floor board that needs repairs before it's too far gone
I've seen a bundle of wires on the passenger side underneath the carpet and I was told by a person in Barrie Ontario who's been using uplanders for quite a few years as Taxis that some of those wires go all the way back
to the rear most small windows that are electrically controlled if that feature is available
The same will probably apply to the driver's side if there's wires under the carpet
The rear sliding doors , tailgate , rear wiper , rear lights , gas hatch etc all have electrical feeds by wires that
probably run under the carpet

Cheers ...... Vinny

12three

did you see this?
https://chevroletforum.com/forum/upl...-start-100924/

12three

I have an interesting note on this:
i was having a problem recently where usually the first few times i touched the brake pedal after startup the abs would engage for no good reason a time or two, then throw the abs light, traction control light, service stability system, etc

the problem was that i had new pads and rotors on one rear side and worn out pads and rotors on the other rear side.
lazy sure, but i was busy. i drove a few hundred miles this way without any real issues other than the warning lights themselves. i slapped on matching pads and rotors to the other rear side and i have not had the lights and symptoms since... that was about 3 weeks back and the lights and symptoms had been a multiple times a day occurrence, especially when one rear pad got to partial metal on metal.

apparently the new side was stopping significantly faster and the vehicle was able to detect it and throw the fault. im not sure how the system works but that is how my experience worked this go round.

notably, i was not losing cruise control this time. i have previously had these lights come and go a handful of times in the past and i would often lose cruise control. i never previously had the issue with the abs randomly engaging. the solutions in those other instances all involved brakes or hub/bearing assemblies. i think losing cruise control was related to the front hub/bearing assemblies bc i havent lost cruise since i replaced my noisy front hub/bearing assemblies. and as a side note i think worn struts likely wreck the front wheel bearings and i would do them together plus an alignment afterwards of course.