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

 

[AXE]

So I decided to take it in to dealer cause I didn't want my wife and kid riding around with sketchy equipment.

When I started it today the SEL was gone, but the codes were still there.....go figure. Cranked just fine and didn't throw any codes. When I got there the SA said it was likely the battery, not the other electrical parts, even though I had tested it myself and it seemed fine. Said he just replaced his starter and battery on a 24.

So GM requires performing tests and data before they will approve warranty replacement. I guess they have a special process to charge and discharge it that takes about 1 hour. They did this battery twice and it didn't fail so they won't replace it until it dies. But they said that it probably is on its way to being dead. "Just call GM customer service if you need a tow"........thanks GM for covering a $200 tow and $250 battery, but not just a battery......LOL

 

[AXE]

SA said batteries were one of the biggest warranty cost items for GM, so they won't just throw in a new one. He said a lot of dealers were abusing the system, so now each one requires the testing and data.

I told him I might just replace it myself to avoid the hassle. He cautioned me on removing the omni fuse block (that big ol black box with all the wire connections on the battery). Said he had people coming in after damaging theirs and it's $500 to replace.

 

[GATORB8]

So I decided to take it in to dealer cause I didn't want my wife and kid riding around with sketchy equipment.

When I started it today the SEL was gone, but the codes were still there.....go figure. Cranked just fine and didn't throw any codes. When I got there the SA said it was likely the battery, not the other electrical parts, even though I had tested it myself and it seemed fine. Said he just replaced his starter and battery on a 24.

So GM requires performing tests and data before they will approve warranty replacement. I guess they have a special process to charge and discharge it that takes about 1 hour. They did this battery twice and it didn't fail so they won't replace it until it dies. But they said that it probably is on its way to being dead. "Just call GM customer service if you need a tow"........thanks GM for covering a $200 tow and $250 battery, but not just a battery......LOL

I'd have either paid for the battery and put it in myself or picked one up on the way home.

Just going to the dealer is a PITA, having to tow it there would suck even more, but listening to my wife bitch about having to do it is a no go for me.

 

[AXE]

I'd have either paid for the battery and put it in myself or picked one up on the way home.

Just going to the dealer is a PITA, having to tow it there would suck even more, but listening to my wife bitch about having to do it is a no go for me.

Like i said a while back, If your gonna drive GM you need a chase truck. She's driving my 1500 now.......probably the easiest 100 miles it's ever seen. She drives my 2500HD too, but doesn't like that she can't see over the hood.

 

[DNZR2]

FWIW the wife’s vette started doing crazy electrical crap just before the battery died.

 

[AXE]

I'd replace the battery, but I've tested it twice with this equipment and it didn't even remotely look dead. Then the dealer spent two hours charging and discharging and it didn't fail for them either. So I'm not convinced it is the battery just yet. I'll check it a couple times a week and see if it changes.

 

[AXE]

FWIW the wife’s vette started doing crazy electrical crap just before the battery died.

Yeah. I don't think it takes much. There's more electrical shit in one of these vehicles than there is in your house. Even a slight voltage drop, the PCM and ECM will detect it and throw codes. If the plates have any type of sulphation, they can touch when vibrating down the road.

I have several different chargers and a few of them have desulphation modes, so I might put one one there for good measure.

 

[AXE]

About 2 weeks since this issue occurred and it hasn't happened again. I have put my smart charger with a desulphation mode on the battery twice. The first time it ran for over 12 hours, the second time about 4 hours before full charge. Not sure there was any long term beneficial results, but the CCA did test higher and compared to the same battery in my truck which is similar age.

I've put my Foxwell digital tester on the battery several times and it rarely reads 12.8V, it mostly floated between 12.4V and 12.6V. I also noticed sometimes it would randomly change when I was watching it. I think there is some occasuonal random draw on the system causing this fluctuation. Perhaps the computers communicating with GM/OnStar or my wifi.......maybe ET.

That got me curious, so I tested my truck a few times and got the same random voltage reading between 12.4V and 12.6V. The only difference was the CCA were 30-60 CCAs higher on that battery and were closer to 800 CCA. I'm not even sure what the max for this battery is supposed to be, but I assumed 750-800 ish for an H7 battery.

Starting to think this is once again software and electronic hardware gremlins and not the battery. We'll see if the battery holds up.

 

[AXE]

This is one of the battery testers I use. It's really nice and can check alternator performance and other metrics there's a newer version available.

FOXWELL Car Battery Tester https://a.co/d/4aWzJzB