[stocklt4]

Hey guys. Thought I’d make this thread to go over some issues I’ve been having and see if anyone else is in a similar boat or has some suggestions. My car is around 26k miles, FBO, cammed, ported blower with a smaller upper pulley. The car behaved perfectly fine for about 10k miles on these modifications. There’s also a TL;DR at the bottom of this post.

Problem Background:
A day or two after an alignment at a random tire shop I started having a “Service StabiliTrak” warning show up while driving. Soon it was extremely frequent and every time I drove. I would also occasionally get “service rear axle” or “service battery charging system” but those were rarer. I’ve even had my dash shut off twice. Currently, these warnings are very erratic and can alternate between not happening very often or happening a lot. When it’s occurring in higher frequency there is also an odd “wub-wub” noise preceding and following the warning. It sounds like some sort of hesitancy in the RPMs. I’ve recently discovered that the more I drive it the more it behaves just driving around town if I'm not hammering it. I don’t get to stretch the legs as often as I want to but if I do a WOT pull there is usually a barrage of warnings that follow until some time has passed or I turn off the car.

Timeline after issue begins:
My tuner checks the car and inspects all wires and finds nothing wrong. No codes show up. We decided to replace the alternator and the car drives fine for a few days before the problem returns.

“Battery charging system” warning increases in frequency and I replace the battery. That warning then reduced in frequency (probably just coincidence) but “Service StabiliTrak” continues to appear.

I take it to my tuner again and he spends a few days with it and is stumped

I take my Silverado in for service and mention my problems to my service advisor. He says they have a really good tech who works on highly modified Camaros/Corvettes and could try to leverage their GM resources.

I bring it to my dealer and they performed a “Global Reset”. They told me that it’s a dealer-only reset that can sometimes help solve these types of issues. Told me the issue is gone but when I get the car back it’s not.

Bring it in for an alignment just to see if that will do anything. Doesn’t help.

Present/Recent:
Take it in for the third time. This time they found codes (C0800, C0805, P0621, B1325) and some damaged wires:
“Technician came to conclusion of repairs needed of a 1 new connector at the generator and 2 new wire re-string due to damage from an outside influence that is not a common failure on circuit #234 and #25. They contacted GM technical assistance and they suggested to check both battery cable positive and ground result was negative battery cable being out of factory specification of .20 volts and actual measurement was 0.335 volts. They recommended to have the negative battery cable replaced.
Soon after the 2nd repair was completed the technician contacted GM to update the case with engineering due to still having P0621 and C0805 present set at 2,000 rpms. GM directed to inspect pulley system for modifications that can cause a high rpm output that’s outside of GM specifications due to those two trouble codes being present.
The technician founds 2 drive pulleys have been replace by a non-factory spec.” This is of course where they insert their *GM said no more repairs or assistance on this vehicle until it’s returned to stock* statement.

Lots to digest here so sorry for the info dump. My crank pulley is stock sized so I’m not sure how that would overdrive the alternator. My tuner stated that there is a voltage regulator and that it shouldn’t matter anyway.

TL;DR
When the engine reaches 2k rpm (corresponding DTCs P0621 and C0805) the ECM has a high voltage reading from the alternator. This triggers or seems to be triggering very frequent “Service StabiliTrak” warnings. It doesn’t always appear when the engine is around 2k rpm but aggressive driving usually brings about a condition where it begins to show these warnings frequently. Quite honestly this is ruining the car for me. Stumped and wondering if anyone has any advice.

[dbs1]

Mine did something similar last week when my son was driving and he used the aeroforce gauge to pull the codes (don't remember which ones) and then erased the codes.

Took it to my tuner shop as well as a Chevy dealer and they can't get it do replicate the problem or show a code. Service advisor did mention it sounded like it was dragging when starting and I may need a new battery. 2017 with 42,000 miles.
I'm thinking for piece of mind I'm going to stick a new battery in there. I'm hoping you figure it out because I'm thinking I may have a very similar issue.

[stocklt4]

Originally Posted by dbs1

Mine did something similar last week when my son was driving and he used the aeroforce gauge to pull the codes (don't remember which ones) and then erased the codes.

Took it to my tuner shop as well as a Chevy dealer and they can't get it do replicate the problem or show a code. Service advisor did mention it sounded like it was dragging when starting and I may need a new battery. 2017 with 42,000 miles.
I'm thinking for piece of mind I'm going to stick a new battery in there. I'm hoping you figure it out because I'm thinking I may have a very similar issue.

Had the issue of it not showing codes as well for a while. Possibly coincidentally, it started storing the codes soon after the global reset at the dealer.

[Tara Martin]

There's a TSB on wire loom chafing on the 2017 ZL1. Has anyone checked into that? I don't remember the TSB number as I deleted my 2017documents when I traded it in.

[Grinch_ZL1]

have you by a chance checked your wiring harness inside the driver side wheel well? i had some similar issues that I tracked down to my tire eating through the fender liner and actually eating through the harness causing weird electrical issues like ur stating. worth a shot....

[Gunkk]

Originally Posted by Tara Martin

There's a TSB on wire loom chafing on the 2017 ZL1. Has anyone checked into that? I don't remember the TSB number as I deleted my 2017documents when I traded it in.

See attached TSBs related to harness rub.

[Evansa22]

Originally Posted by Grinch_ZL1

have you by a chance checked your wiring harness inside the driver side wheel well? i had some similar issues that I tracked down to my tire eating through the fender liner and actually eating through the harness causing weird electrical issues like ur stating. worth a shot....

Is this front or rear wheel well? Starting to have similar issues

[Camaro1973]

Originally Posted by Evansa22

Is this front or rear wheel well? Starting to have similar issues

Driver rear.

[Evansa22]

Thanks

[dbs1]

My son was out driving mine this evening and let me know it hit freak out stage again and this time I told him NOT to erase codes or anything and get it to the shop. I'm going to have them start with the wiring of the jms voltage booster, then clean the connectors on the ported tb.
Then if they haven't found anything I'll have them check the wiring loom at drivers side rear, although when I first got it I relocated it slightly per info on the board but...it was running 315 Toyo rrr's then and since I've changed to 325's, so maybe?

[stocklt4]

Thank you for all the responses guys, seriously.

Originally Posted by Grinch_ZL1

have you by a chance checked your wiring harness inside the driver side wheel well? i had some similar issues that I tracked down to my tire eating through the fender liner and actually eating through the harness causing weird electrical issues like ur stating. worth a shot....

Originally Posted by Gunkk

See attached TSBs related to harness rub.

Going to be looking into this, thank you guys. Having my shop take a third pass on it and we will specifically look for any of these things.

Originally Posted by dbs1

My son was out driving mine this evening and let me know it hit freak out stage again and this time I told him NOT to erase codes or anything and get it to the shop. I'm going to have them start with the wiring of the jms voltage booster, then clean the connectors on the ported tb.
Then if they haven't found anything I'll have them check the wiring loom at drivers side rear, although when I first got it I relocated it slightly per info on the board but...it was running 315 Toyo rrr's then and since I've changed to 325's, so maybe?

Does anything seem to 'trigger' the freakout. After fixing my alternator connector it mostly is doing it when it's cold or when I'm flooring it or more than half throttle suddenly.

[SCCAForums]

If your drivers side wiring harness is not rubbed, this is a low battery. Trust me… I’ve experienced every fault known to man for a perfectly good battery being just “a little” low…

Happened again this past weekend at SEMA Optima ultimate street car… I was unable to disable traction control, and had a “service rear diff” error. Once we got battery charged… everything came back perfectly fine.

These cars put a tremendous strain on the electrical system, and the intelligent charging leaves much to be desired.

Best regards,
Dave

[radz28]

Is there an issue with the alternator or something? I feel like I've seen and read some people have issues with them on these cars.

One thing I have noticed is when I leave the car off the battery tender for more than a couple days, when I hook one back up to the battery, it registers the battery very low. Maybe the tender (an Optima) is exaggerating or whatever, but it seems to me the electrical load, even sitting, is HUGE. I just looked-up the alternator for these cars and it's 220-AMPS. It wasn't that long ago Escalades came with 140-amp alternators, and that was HUGE!!!

[stocklt4]

Originally Posted by radz28

Is there an issue with the alternator or something? I feel like I've seen and read some people have issues with them on these cars.

One thing I have noticed is when I leave the car off the battery tender for more than a couple days, when I hook one back up to the battery, it registers the battery very low. Maybe the tender (an Optima) is exaggerating or whatever, but it seems to me the electrical load, even sitting, is HUGE. I just looked-up the alternator for these cars and it's 220-AMPS. It wasn't that long ago Escalades came with 140-amp alternators, and that was HUGE!!!

Alternator was replaced a while ago and it fixed it temporarily for 3 days. Also replaced a connector to it at the recommendation of GM very recently. That didn't fix it either. The current codes I'm getting are all alternator codes as well right now.