[Cechk01]

Originally Posted by 918Stealth2SS

I have a current chevy case going since April with this exact issue. They cant figure it out.

keep going at it. took my dealer 4 tries and 500ish test driving miles to figure mine out. they ended up replacing the alternator, gauge cluster, a ground wire that goes from right behind the alternator to the jump stud, various power wires in that area. they also added a couple redundant grounds. You tech will need to twist GMs arm to pay for warranty parts.

try flashing the highbeam, pulling up on both windows even when they are closed. keep an eye on what voltage the issue happens at. Use the heated seats and rear defroster to put extra load on the electrical system, not the headlights, that triggers the car to boost the voltage. mine rarely happened at ~14ish volts, so never at night or when the wipers are on.

I'd be happy to answer any questions. I dug into this quite a bit when i had the issue.

[trohde78]

I had this happen on my car, and it was a loose ground wire at the jump stud. It was because I didn't tighten it enough when I did some work, but it caused that exact condition with the tach.

[srcstc]

Originally Posted by Cechk01

keep going at it. took my dealer 4 tries and 500ish test driving miles to figure mine out. they ended up replacing the alternator, gauge cluster, a ground wire that goes from right behind the alternator to the jump stud, various power wires in that area. they also added a couple redundant grounds. You tech will need to twist GMs arm to pay for warranty parts.

try flashing the highbeam, pulling up on both windows even when they are closed. keep an eye on what voltage the issue happens at. Use the heated seats and rear defroster to put extra load on the electrical system, not the headlights, that triggers the car to boost the voltage. mine rarely happened at ~14ish volts, so never at night or when the wipers are on.

I'd be happy to answer any questions. I dug into this quite a bit when i had the issue.

Thank you


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[blpadge2]

Thought I was the only one having this issue.

Background, 2016 Camaro 2SS convertible with A8 auto. Tach needle bounces around randomly at idle (just like in the video), or coming to a stop, sometimes just cruising in traffic. What is worse is I have caught the tach on the HUD doing it to, so I suspect it is not a gauge issue but a sensor issue. Guess it is off to the dealer then before the warranty goes out in Oct. (but good thing I bought the extended).

Side note, had something similar happen in my 1988 Beretta GT (first car I ever bought). It had the digital dash option, and would randomly light up the entire dash, then go dark. Dealer ended up replacing dash before learning it was the primitive ECM acting up.

[Cechk01]

Originally Posted by blpadge2

Thought I was the only one having this issue.

Background, 2016 Camaro 2SS convertible with A8 auto. Tach needle bounces around randomly at idle (just like in the video), or coming to a stop, sometimes just cruising in traffic. What is worse is I have caught the tach on the HUD doing it to, so I suspect it is not a gauge issue but a sensor issue. Guess it is off to the dealer then before the warranty goes out in Oct. (but good thing I bought the extended).

Side note, had something similar happen in my 1988 Beretta GT (first car I ever bought). It had the digital dash option, and would randomly light up the entire dash, then go dark. Dealer ended up replacing dash before learning it was the primitive ECM acting up.

Yup both the HUD and the real tach run off a duplicated camshaft position sensor signal from the ECU. The issues is caused by when electrical noise makes it way on to that wire.

[adnan92]

I’m having an issue also the rpm bouncing crazy and getting worse when the A/C full blast and in hot weather, also in the night after driving the car for a while headlights start to blinking and sometimes CEL on . I changed the battery and I checked the 2 wires behind the engine belt and also the dealership checked the ground wires . I don’t know is that a bad ECM or fuse box ??? What it could be???
Please help

[Cechk01]

Originally Posted by adnan92

I’m having an issue also the rpm bouncing crazy and getting worse when the A/C full blast and in hot weather, also in the night after driving the car for a while headlights start to blinking and sometimes CEL on . I changed the battery and I checked the 2 wires behind the engine belt and also the dealership checked the ground wires . I don’t know is that a bad ECM or fuse box ??? What it could be???
Please help

A bad ground can cause all these issues.

[cerino2000]

Anyone ever find the problem? Have same issue. All grounds good.

[SSDan]

Originally Posted by cerino2000

Anyone ever find the problem? Have same issue. All grounds good.

Check out the thread I attached. Adding a robust ground cable has helped out a lot of people with electrical gremlins (like a bouncing tach) and hot start issues especially on the 2016/2017 models. I believe the factory engine to body ground is inadequate/deficient. Adding the cable is must easier that trying to troubleshoot and fix the factory ground. It will cost you less than $20.00 for a good cable and take ten minutes to install. Even if it doesn't fix the problem it won't hurt anything as there is no such thing as having too good of an engine to body ground.

https://www.camaro6.com/forums/showthread.php?t=586153