Electrical gremlin

[wu6fiend]

Weird thing happened today.

Was out running errands, and went to start the Yukon. Pressed the start button, and it cranked very sluggishly. Took a few cranks, then started, but not strongly. Sort of stumbled to life. Immediate dashboard warning message, "Service Trailer Brake". Then I noticed all of my presets on my radio were gone, just numbers. XFM displayed, but no channel, just a long series of letters and numbers.

Drove fine, with no other warning messages. Radio presets remained gone, and I could not add them back. Every time I did, got another warning message, this time something about "Favorites may not be on this device". I could tune the radio, and change from AM/FM/XFM/CD but favourites were still gone, and XFM only showed a long series of letters and numbers.

Up until starting the engine this time (this was after driving it for at least 30 minutes solid, with no error messages or issues whatsoever) all was normal. The problem with the radio persisted all the way home, another 30 minute drive.

Did some online research, and this seems similar to issues with a software update experienced by Buick, Cadillac and GMC owners of 2018 models (TSB 19-NA-100 refers). Lots of complaints of lost radio presets. One suggestion was to restore the vehicle to factory settings. So I went out to try that.

Started the Yukon, started normally. And my presets are all back, no warning messages displayed. No trailer brake warning, or rear camera warning either (that message appeared, but only once a few months ago, never since).

Maybe a battery issue? I'm going to stop at the shop tomorrow after work, and get it load tested.

 

[wjburken]

Weird thing happened today.

Was out running errands, and went to start the Yukon. Pressed the start button, and it cranked very sluggishly. Took a few cranks, then started, but not strongly. Sort of stumbled to life. Immediate dashboard warning message, "Service Trailer Brake". Then I noticed all of my presets on my radio were gone, just numbers. XFM displayed, but no channel, just a long series of letters and numbers.

Drove fine, with no other warning messages. Radio presets remained gone, and I could not add them back. Every time I did, got another warning message, this time something about "Favorites may not be on this device". I could tune the radio, and change from AM/FM/XFM/CD but favourites were still gone, and XFM only showed a long series of letters and numbers.

Up until starting the engine this time (this was after driving it for at least 30 minutes solid, with no error messages or issues whatsoever) all was normal. The problem with the radio persisted all the way home, another 30 minute drive.

Did some online research, and this seems similar to issues with a software update experienced by Buick, Cadillac and GMC owners of 2018 models (TSB 19-NA-100 refers). Lots of complaints of lost radio presets. One suggestion was to restore the vehicle to factory settings. So I went out to try that.

Started the Yukon, started normally. And my presets are all back, no warning messages displayed. No trailer brake warning, or rear camera warning either (that message appeared, but only once a few months ago, never since).

Maybe a battery issue? I'm going to stop at the shop tomorrow after work, and get it load tested.

I would also check all your power and ground cables and connections. Make sure there is no corrosion under the terminals.

 

[wu6fiend]

Good idea. Does anyone have a schematic, showing where all the ground connections are located on the 2015-2020 platform?

 

[wu6fiend]

So the alternator is fine, but the battery check produced an ambiguous result (the machine said the battery needed to be charged). I had driven the vehicle for about 15 minutes, and it had started fine after sitting all day. So I will take it back next week, and see what the additional check reveals (they are going to put it on a charger for a few hours, and then check it again). I was told I was the fifth person to come in that day, with battery issues. May be related to the sudden cold temperatures. I'm hoping its just a 4 year old battery, at the end of its life.

No sign of the gremlin, and all my radio presets are present and accounted for (and neither the "Service Trailer Brake" or "Service Rear Camera System" warning messages have reappeared).

 

[tsuintx]

Four years is pretty much the life cycle of a battery nowadays.

 

[sealandsky]

My personal policy is to replace every 3 years and never stretch it out. However, I am in Minnesota and need my truck to start after being parked for a week in below zero temperatures.

 

[wu6fiend]

Had the battery tested again, after a couple hours on a charger. Marginal result. So its being replaced with a Optima Yellowtop, which is the same battery I replaced the OEM one in our last 2009 Denali. Lesson is, if you are having electrical issues, and your vehicles is more than a couple years old, start with a battery check.

 

[wu6fiend]

Final update on this: had the battery replaced with a NAPA Legend Premium, with a 6 year warranty and more cranking power than OEM.

What was concerning was the original battery (4 years old) was split, and leaking from the bottom. Luckily, the battery tray was undamaged, and everything else under the hood was ok too.

So, if you have a truck that is a few years old, might be a good idea to have a close look at your battery, even if it appears to be operating fine.

 

[Tahoe14]

Glad you found the problem, batteries can be very finicky and cause all sorts of problems with a cell dying or leaking from the bottom like in your case, and can be hard to diagnose. Thanks for reporting back.