At a loss with electrical/mech problems - 2015 Tahoe LTZ

Following the spring weather shifts I've had some strange issues starting up with my Tahoe and no one thing is really matching with the other from what I could find so I figured I'd see if there's someone who's had similar issues or knowledge on what this could be

- every few days a cold start via remote start will fail, and that causes the entire infotainment system and memory seats to reset, occasionally also prompting a Service Theft Deterrent light on the dash which goes away after the next startup.

-the car can and has died in traffic, but I can't find the cause for it at all. It does seem to be linked to power draw in some form though, I've had it happen most commonly in turns.

-linked to the previous, it also freaks out at random when going above 2-3k rpm, dash flickering and throwing up random flags for all sorts of different components anywhere from Stabilitrak to the trailer brake harness, all of which go away after letting off the gas.

-usually following up these the car dies completely after being turned off, and as of the last couple days it has been happening every time I turn it off, whether it be a 5 minute or hour drive.

I replaced the battery in both remotes (assuming it was the theft deterrent system at first) and replaced the battery in the car itself (from an AGM to a flooded batt) which seemed to hold it fine for a month before the issues restarted once more.

Currently I'm at a loss, I've got a few things on my list to check into but for curiosities sake I figured I'd see if anyone had any insight. Only things I can think of currently are
-bad grounds on the car itself
-(my best guess) bad alternator
-fuses
-battery cable corrosion
-BCM

Anything helps ty!

Replace the negative and short positive (on top of the battery) battery cables. Classic high resistance symptoms.

91RS said:

Replace the negative and short positive (on top of the battery) battery cables. Classic high resistance symptoms.

Click to expand...

Ty! I'll shop around for that tonight then

Wouldn't hurt to do a standard voltage drop test.

If you still have problems, I might consider the alternator. I had an old Mazda that acted all kinds of crazy before the alternator gave up the fight. You mentioning that the new battery fixed it for a month before acting up again is very reminiscent of my troubles with that car. Good luck.

Replace battery

I wouldn't engage the parts cannon quite yet

my suggestions
- test the current state of the battery, it is fully charged or is it discharged (if isn't low, either it isn't being charged or some draw is pulling it down)
- test the alternator, is it outputting as intended

my guess is that that above are likely fine or you would have noticed low voltage via the gauge in the dash

inspect the cables as described above, are they nasty or all good, sometimes they can be hard to see; these fail

when it occurs, what does the gauge show? is the voltage down?

I have a 2015 Tahoe LTZ and was having the same exact problems you’re experiencing for a couple years. Crazy codes, flashing infotainment screen, it would randomly die & start back up on its own, etc… Replaced the battery, positive and negative battery cables, replaced the alternator… each fix would work for a little bit, but the problems would always return. Searched high and low for solutions and finally succumbed to taking it to the dealership. $1000 later, the problem ended up being corroded grounds behind the fuse panel, and along the fire wall. I can’t tell you exactly where they are because I wasn’t aware of the locations of these grounds, however, I can tell you that this fixed my Tahoe and (knock on wood) I haven’t had any issues for a couple years now.

I had a 2015 LTZ and it was non-stop electrical issues after 150k miles. Glad it’s gone!

Foxguy1973 said:

I have a 2015 Tahoe LTZ and was having the same exact problems you’re experiencing for a couple years. Crazy codes, flashing infotainment screen, it would randomly die & start back up on its own, etc… Replaced the battery, positive and negative battery cables, replaced the alternator… each fix would work for a little bit, but the problems would always return. Searched high and low for solutions and finally succumbed to taking it to the dealership. $1000 later, the problem ended up being corroded grounds behind the fuse panel, and along the fire wall. I can’t tell you exactly where they are because I wasn’t aware of the locations of these grounds, however, I can tell you that this fixed my Tahoe and (knock on wood) I haven’t had any issues for a couple years now.

Click to expand...

That's what I've been coming across and I appreciate the insight, I hear the GM grounds on these SUVs are absolutely atrocious. I'll probably have to hunt them down n clean them up myself

ReaperHWK said:

I had a 2015 LTZ and it was non-stop electrical issues after 150k miles. Glad it’s gone!

Click to expand...

I'm a sucker for the style of this gen specifically, even if it ain't worth the headache, it's my headache to bear, and a beautiful one at that!

steiny93 said:

I wouldn't engage the parts cannon quite yet

my suggestions
- test the current state of the battery, it is fully charged or is it discharged (if isn't low, either it isn't being charged or some draw is pulling it down)
- test the alternator, is it outputting as intended

my guess is that that above are likely fine or you would have noticed low voltage via the gauge in the dash

inspect the cables as described above, are they nasty or all good, sometimes they can be hard to see; these fail

when it occurs, what does the gauge show? is the voltage down?

Click to expand...

I've had both the battery and alternator checked and both are reading exactly as it should, haven't made it to the drop test quite yet as I need to pick up a multimeter cuz mines packed away somewhere. The voltage does fluctuate randomly but it is always consistent with it, always reading at 12 or 14 even right before it cuts out.

Reading more and more about it screams faulty grounds or cables, so I'm gonna take some sandpaper to it here soon and see what I can find

A little odd note that justifies the thought, when the car gets wet (car washes, rainy weather) it stays fine and maintains a consistent clear startup, so I'm starting to think it's a frame ground specifically if it is that.

Basecamp said:

Replace battery

Click to expand...

Did that, was fine for a month then resumed issues

TheBigCheezeBall said:

If you still have problems, I might consider the alternator. I had an old Mazda that acted all kinds of crazy before the alternator gave up the fight. You mentioning that the new battery fixed it for a month before acting up again is very reminiscent of my troubles with that car. Good luck.

Click to expand...

It's on the list of potentials, I'm probably gonna start with the easiest/cheapest and work up to avoid an unnecessary 500 dollar part, gonna throw in a 170 in there over the 150 when I do

Fless said:

Wouldn't hurt to do a standard voltage drop test.

Click to expand...

That's next up! Gonna try to root out the problem after I pick up a new multimeter, ty ty

ickegart said:

Did that, was fine for a month then resumed issues

Click to expand...

That is a frustrating thing, unfortunately GM put a mid-size car charging system in a vehicle that needs enormous power. I also replaced the stock 150a alternator with the 170a. GM Genuine Parts 84143540 Alternator. Amason has 1 right now labeled used for $100 off. Side note, all used parts suck and eBay is all counterfeit, the exception to that is Amason sold and shipped by amason. They are all brand new unused that someone broke the factory seal and sent back. Also, start replacing your grounds, they rust and can cause odd behavior depending on weather. Good luck!

Basecamp said:

That is a frustrating thing, unfortunately GM put a mid-size car charging system in a vehicle that needs enormous power. I also replaced the stock 150a alternator with the 170a. GM Genuine Parts 84143540 Alternator. Amason has 1 right now labeled used for $100 off. Side note, all used parts suck and eBay is all counterfeit, the exception to that is Amason sold and shipped by amason. They are all brand new unused that someone broke the factory seal and sent back. Also, start replacing your grounds, they rust and can cause odd behavior depending on weather. Good luck!

Click to expand...

Good call on the Amazon used alternators, scooped one soon as I saw this. The grounds are a must do though, as I believe that's what my root problem is. Gonna do some research on locations and maybe some further prevention. Much appreciated!

Spend the money and buy access to the complete wire diagram for your specific vehicle. Some places offer this for less than $50.

With the full wire diagram it will break down all grounds, what they attach to and where they actually ground in your car. Unless you have multiple failed grounds you will probably trace your problem to one ground location with multiple wires grounded at that site. 99.9% of all Tahoes/ Yukons on the road get by just fine with the factory supplied 150 amp alternator so don’t sweat that unless yours is not working or is failing.

Intermittent failures are the hardest to find.

A scan tool, multi meter and the wire diagram should put you on the right course to a solution. Best of luck and be prepared to invest time.

Many shops run from electrical issues because they never know if they will have 1 hour or 25 hours invested.