Every possible light came on. Dash went dead. Truck went into limp mode. Questions...

Shoup1cobra · December 8, 2020

2019 Silverado WT 4.3L. It's lifted 6" with 35". Hypertech speedo recal. Less than 8k on the truck.

Problem:

I was driving home Tuesday on the expressway. I lost all gauges (except battery) Every service light came on (engine, stabilitrack, power steering, traction control, etc...) Power to engine was reduced. Power steering assist was pretty much gone. I could not maintain speed. I made it to the next exit, and when I accelerated, it was much better. The next day, remote start would not work. I got gas (when the dash goes dead, I can't see how much fuel I have) after waiting for a pump, I pulled in and barely made it to the hose. I took it to the dealership right then (it made it, thankfully.) The dealership has had it since Tues. I got a call back today that they did a brake controller reprogram and the problem still persisted. They unplugged my OBD port light hookup (Amp style so lights come on with unlock/door open etc...) The dealership is blaming that as the cause. It has been installed since the summer with zero issues (I did try to tie a ground to it once, but the lights never shut off, so that ground had to be on it's own. It's been fine since then.) The technician drove it for ten min and gave it the all clear. I go pick it up tomorrow. The service advisor said that the OBD plugs can cause issues like this when things are plugged into them (the insurance trackers are one that she mentioned.) Not sure I buy into that.

The only changes I made to the truck in the days before this happened are new LED DRL headlight assemblies/PIAA bulbs about ten days before. Those have been OK. I also added four lights on the roll bar over the summer. These are tied into the wiring in the third brake light cab spoiler (The upfitter wires) and the harness end under the dash is wired to the extra slot on the pass fuse box that everyone seems to be using. The ground is to the metal by the driver side fusebox. This has been ok for months. The weekend before the issue, I added LED's behind the grill. I tapped into the same upfitter wire underneath the dash and ran it through the rubber firewall finger for power. I grounded the LEDs under the hood to the RH front fender bolt (Good contact, cleaned of paint.) That was fine for a few days.

All that being said:

Is the OBD port excuse legit?

Is it possible/likely that the ground in the engine compartment is causing all this (since that was the most recent change.) I could run it to the ground that the roll bar lights are using, if needed (wouldn't be the easiest though.)

Any other things I should look into as a cause?

Thanks for any help.

Jay P · December 8, 2020

Look at this TSB. It's easy to check and can cause all kinds of odd electrical issues.

Jay

BUELLTIN.pdf

Shoup1cobra · December 8, 2020

34 minutes ago, Jay P said:

Look at this TSB. It's easy to check and can cause all kinds of odd electrical issues.

Jay

BUELLTIN.pdf 1.02 MB · 5 downloads

I'll check that out for sure. I had the fuse box cover off when doing the LEDs. I was going to to an add-a-circuit to the box to power them but couldn't get 12v even with the ignition on. Easy enough to check at least. Thanks for the link!

Shoup1cobra · December 9, 2020

The dealership didn't seem so interested in the fuse box tightening. Couldn't get the service advisor or the technician to buy in to it. They insisted it was the OBD port light, which they left unplugged. The porter brought the vehicle from the side of the lot to the front. By that time, the CEL was back on. Clowns. I told them to keep it until tomorrow. They are now blaming the Hypertech speedo recalibrator, which has been installed in the truck since May. Absolutely a joke. Will be taking the truck elsewhere, if it continues to act up (after I retorque the fuse studs myself.)

Edited December 9, 2020 by Shoup1cobra
spelling

Shoup1cobra · December 10, 2020

I tightened the fuse box stanchions myself. One minute at most. They were not loose, but also not tight. I got maybe a half turn on them without going overboard (only a 1/4" ratchet) The dealership is blaming "that programmer you had in there" which was just a Hypertech speedo recal. They pulled it out and it's been fine. I'm just off a few MPH now. We'll see if it happens again. Seems OK so far.

davester · December 10, 2020

Note, GM can void your powertrain warranty if the mileage of the vehicle isn't accurately known, which happens when the tires are a different size than what the vehicle is programmed for...