Need help with intermittent electronic failure - diagnostics included

[harpua555]

I have been having intermittent problems with a 2015 Tahoe. This has happened 4-5 times over the last 6 months. About half happened while driving, the other half were a fail to start condition that once started still displayed symptoms.

Symptoms include:
All IPC gauges go to zero, but are still illuminated
All service dialogs come up in succession
Turn signal physically comes on but no audible signal
Media console goes dead, sometimes with backlight, sometimes without
HVAC will run the fan at requested speed but will not turn on AC compressor.

Two times this happened, I was unable to turn the ignition (push button) off once parked. Had to leave running for ~30 minutes until the issues resolved and the car could be turned off.

Most recently, the car would not start. After about 20 minutes of different attempts to start, the engine finally turned on, but all of the electronic problems persisted.

I have never lost power steering/braking, haven't had stabilitrak turn the wheel on me, etc. No drivetrain/engine problems.

I have already checked the ground under the dash/A Pillar for trapped foam, does not appear to be any issue there (saw in another post).

Just ran two diagnostics - one with OBDLink MK+ and one with LAUNCH device, which are attached below.

Battery was replaced two weeks ago after issues started, so battery can be assumed healthy. Issues were not resolved by battery change.

Thanks!

 

[harpua555]

Also wondering if it is worth clearing the codes to see what comes back?

 

[Fless]

What does "the car would not start" mean? No crank? Cranks but doesn't fire?

If there's another report you can save, do that. But it looks like the Launch report is comprehensive. Then clear the codes and see what comes back. I'm going to assume that the battery and alternator are healthy and have been tested.

We've seen some issues on here with the side detection module corrupting the network. Apparently disconnecting it has been helping cure this, at least temporarily. You might want to search for that issue.

 

[harpua555]

Car wouldn't even click, the button was just trying to (I think) go into and out of accessory mode - no attempt made to actually start.

I have since found a horribly corroded ground on the frame behind the drivers wheel. I ground that down to bare metal, put some dielectric grease on it, and refastened it. I cleared the codes at that point and took it for a test drive. All I am seeing now are two codes:

U0232-00 - Lost Communication with Side Object Detection Control Module - Left
P2537-00 - Ignition Accessory Switch Circuit Low Voltage

I am running this scan in the "hold the start button for 10 seconds" level 2 accessory mode.

How would I disconnect the side detection module? Can I pull a fuse, or would I need to pull the harnesses from the modules?

 

[Joseph Garcia]

Welcome to the Forum from NH.

Lots of knowledgeable folks here who freely share their knowledge, experiences, and perspectives. Knowledge is power.

I hope that you will become a participating member in the Forum's discussions.

Pics of the truck, please.

You are already receiving sage advice from the knowledgeable folks on this Forum, and other folks will chime in.

 

[harpua555]

Thanks! VT here, so the salt is definitely doing its thing...

Best I can do for pictures right now is the two grounds I checked!

G218 -

https://imgur.com/a/tJqAXbJ

G??? (behind driver wheel) -

https://imgur.com/a/bjgkg7w

The second one is the one I flapwheeled down to metal~ish and put dielectric grease on

 

[Kelly Craft]

on my 08 i had multiple electronic issues i chased for weeks finally found wire harness under fuse/relay box was rubbing on upturned raw edge of fender and had wore through some wires and was shorting out others. repaired damaged wire and split a rubber hose so i could slip it over that sharp edge of the fender.

 

[fozzi58]

99% of electrical gremlins can be traced back to ground cable corrosion. These cables are known to corrode on the inside of the insulation, even when the ends look good.

That was the case in my truck (17 Suburban). There were times my truck would literally "reboot" at 50mph. I ended up replacing all the ground cables and adding a few extra. The factory battery cable looked perfect on both ends but looked like the Statue of Liberty when I split the rubber in the middle of the cable.

I replaced the main ground and battery to body ground (behind passenger wheel) with 0 & 8 gauge cable respectively. Also added an additional 8 gauge ground cable from engine to body and yet another battery to body. I used a 3 post terminal for the ground side to get the extra cables on.

I did what you did - ground down the frame to bare metal, used high quality copper ends and added heat shrink as well to seal the rubber to copper connections. Then coated the body and frame grounds with undercoating to make sure they stay fresh and clean.

That was 3 years ago and haven't had an issue yet.

 

[WPSOSteve]

Electrical issues can be a nightmare. Recently we had a 2014 Tahoe in the shop that had many of the same issues that you named. Long story short, we finally started checking every wiring connection and found that the main connector to the transmission wasn't connected firmly. Not sure if that will correct your problem but a good check of all connectors would be a good place to look. Steve

 

[harpua555]

I have a new negative battery cable to install, but I am having trouble with the connections. I found the 10mm ground right behind the passenger wheel, which should be easy enough, but it seems like the 13mm is connected to an impossible to reach bolt on the engine block. If I were to remove this bolt and not be able to get the new negative in there, would I be okay to remove a different bolt and ground the new cable elsewhere on the engine block?

 

[Joseph Garcia]

I have a new negative battery cable to install, but I am having trouble with the connections. I found the 10mm ground right behind the passenger wheel, which should be easy enough, but it seems like the 13mm is connected to an impossible to reach bolt on the engine block. If I were to remove this bolt and not be able to get the new negative in there, would I be okay to remove a different bolt and ground the new cable elsewhere on the engine block?

Yes, you can ground the engine block using a different bolt going into the engine block.

 

[harpua555]

Just wanted to update this post for anyone that comes across it searching. My symptoms completely resolved after grinding down the two grounds to the chassis by the driver and passenger wheels.

I used an angle grinder with a flapwheel, got down to bare metal, used some dielectric grease, and then spraysealed.

 

[Joseph Garcia]

Just wanted to update this post for anyone that comes across it searching. My symptoms completely resolved after grinding down the two grounds to the chassis by the driver and passenger wheels.

I used an angle grinder with a flapwheel, got down to bare metal, used some dielectric grease, and then spraysealed.

Thank you for getting back to us on the resolution of your issue. This is a very common point of failure, and I'm glad that found and corrected it.

Please add the word "FIXED" or "SOLVED" to your thread's title, to let others who are experiencing a similar issue know that this thread has an identified solution.

 

[harpua555]

Coming back to unfortunately report that the fix was not fully successful.

At this point, the car runs fine if the weather is dry. After/during any good rain, however, the electrical problems come back.

Since repairing the grounds, the issues now exclusively happen in wet conditions, are always the same (no more random issues), and always resolve when the car dries out.

Issues:
Will not turn off
Gauges on the IC are at 0 or bounce between a value and zero
Will shift into park, however the IC does not know this and does not show the vehicle as parked, then cannot shift back into drive
Most system warnings (service xyz system) scroll across the screen
No audio from turn signals (lights still function)
Antitheft kicks on

I am usually able to get it to turn off after multiple attempts, or by turning the key to unlock and holding it in that position for 60 seconds. Once it is off, it will not turn back on until it dries out.

I don't see any water around the sunroof or on the driver/passenger floor, nor do I see any obvious signs of corrosion in either interior fuse boxes. I found a TSB for Chevys from this time period (not the Tahoe/Suburban) which had the exact same symptoms due to water intrusion - https://static.nhtsa.gov/odi/tsbs/2015/SB-10024244-3287.pdf

Wondering if anyone knows where the best place to start might be?

 

[blondie70]

Seems that I remember something about the big lightinng cable in the back by the bumper. It gets corroded and causes crap like this. Maybe do a search for it ??? good luck

 

[Dustin Jackson]

@harpua555 Have you replaced the main negative battery cable?

 

[ReaperHWK]

Your canbus is being corrupted by a bad module that is probably acting up when there is moisture intrusion.

I’d start with the side detection modules as they are located in the rear bumper and get coated with road grime/salt/water. Unplug both and see if that solves the problem.

On these trucks one bad module can cause the whole bus to go haywire.

Dealer techs also do this and start unplugging modules to diagnose. They usually start with one that always has a consistent code thrown.