Electrical Problems

[AXE]

Not sure what's wrong with Tahoe, but wife noticed the mirrors and electronics were slow at boot up when she went to leave for work. Got some brake system failure messages in the DIC at start up.

I figured it might be dead battery at about 2 years old. Battery was a little low at 12.4V and it load tested fine. Also booted up and started fine for me. Alternator was charging fine at 14.8+V. Could be an intermittent short in battery too.

It runs and everything seems to work, but it still has some codes and SEL showing. I think there may be some other electrical issue. Some "pending" fault codes in the computer, but they wouldn't clear for me. Not sure what the hell "pending" implies unless it detects an anomaly and knows it will fail again.

Always some bullshit with these electronics. I'll probably have to run it in for some better diagnostics, especially for the brake failure message.

 

[SGRACING]

Not sure what's wrong with Tahoe, but wife noticed the mirrors and electronics were slow at boot up when she went to leave for work. Got some brake system failure messages in the DIC at start up.

I figured it might be dead battery at about 2 years old. Battery was a little low at 12.4V and it load tested fine. Also booted up and started fine for me. Alternator was charging fine at 14.8+V. Could be an intermittent short in battery too.

It runs and everything seems to work, but it still has some codes and SEL showing. I think there may be some other electrical issue. Some "pending" fault codes in the computer, but they wouldn't clear for me. Not sure what the hell "pending" implies unless it detects an anomaly and knows it will fail again.

Always some bullshit with these electronics. I'll probably have to run it in for some better diagnostics, especially for the brake failure message.

Axe
The misses Suv had the exact same issue,
It ended up being the ground at the post was corroded . I pulled the battery and I just happened to have a fresh AGM in stock .
Put it in after cleaning the post connector and reset all codes and off she went..
What's cool is all three of my GM vehicles use
the same battery... What luck!
I put her battery on the trickle charger and tested it , it was fine. Last October my 23 battery was zero volts do to over the air updates.. I was stranded up to camp and I had one delivered. I put the original on the machine and restored it back to life and put it back in.
Hence the spare.
Good luck with your search.

 

[GATORB8]

Multiple low voltage codes definitely point to battery to me. Last few vehicles have been Stellantis, but would see dying batteries as low voltage errors in all sorts of modules, including TCS/ABS.

EDIT, note the errors would start before the battery started failing testing by a week or two.

 

[AXE]

Yeah the batteries don't last long anymore. My terminals look pretty clean, but wouldn't hurt to pull them and hit em with a brush. The battery cables are a mess in that they have multiple leads and connectors going to a host of diffrrent electronics.

I had the battery cables fail on my last Tahoe about 8 months before I sold it. It threw all kinds of codes. Corrosion was way down inside the cable, not at the ends. Cost me $700 for new cables and labor.....WTF. Also the alternator went some time before that and did the same when the battery wasn't charging.

I just ran some errands and drove it about an hour. Seems to run fine and charging shows normal. Tested the battery again when I got back and it showed 14.63V and 726 CCA.

Pulled the codes again and was a little different, but still points to brakes, PCM, ECM. So there is some kind of voltage drop or signal loss going to the brake system.

I'll probably just go sit at the dealer again for 3 hours. I'm a frequent flyer now.

 

[SGRACING]

I feel your pain.
When I got back from camp and recharged the original battery I made an appointment for the infotainment system reprogram it took five hours total two for the infotainment system and 2 plus for the battery alone to tell me it tested fine and they weren't going to replace it or reimbursement for my cost.
What a joke