Flickering lights

[petethepug]

Our 08 YXL Denali did that when the a/c cycled the engine fan to high speed but only on the headlamps. I lived with it until sold it.

Still scratching my head on what it was.

 

[Fless]

Did the voltage drop tests include body grounds as they relate to the engine block and the battery negative terminal?

And the positive from the alternator lug, and the megafuse lugs, to the battery positive terminal?

 

[Doubeleive]

Yes. I tried cleaning them but still flickering so replaced everything. That terminal comes with the GM replacement cable that runs to the fuse box. The new fuse looks rusted but it's not..the brass came that color from the factory. View attachment 436031

where did you source that? shouldn't be a spec of rust on a new oem one if you got that from a dealer I would be asking them wtf?

 

[solli5pack]

where did you source that? shouldn't be a spec of rust on a new oem one if you got that from a dealer I would be asking them wtf?

It's from Rock Auto and came in a genuine GM box. It looks a lot like rust in the picture but it's not.

 

[bacon612]

Hey OP. I just saw this thread after posting this one. Not trying to cross post but it sounds like we may have the same issue.

2014 Suburban Electrical gremlins

Hello everyone. Just realized that this sub exists. I've been troubleshooting an electrical issue on my suburban where my radio cuts out, I have headlight and interior lights flickering as well as some unstable and high voltage. Truck has 125k miles. Things I have done so far... New battery...

www.tahoeyukonforum.com

What I don't fully understand is how to test resistance on my grounds with my multimeter but this sounds like it might be the way forward.

I've read that g203 is a problem with these trucks and is located on the driver a pillar under the dash. A pain to get to as you have to remove the dash to get to it.

 

[solli5pack]

I think your problem might be a little different than mine since you actually have some devices not working properly. My only issues is flickering lights. As far as checking grounds I check resistance by putting the multi meter on ohms and placing one probe of the meter on the negative battery terminal and the other probe on the ground you want to check. You should have very close to zero resistance. Also using the same procedure make sure there is close to zero voltage between the two.

 

[solli5pack]

Did the voltage drop tests include body grounds as they relate to the engine block and the battery negative terminal?

And the positive from the alternator lug, and the megafuse lugs, to the battery positive terminal?

I've checked every combination possible and no voltage loss anywhere.

 

[solli5pack]

It's probably the alternator. The original on my 2008 Denali started doing that on a trip from CA to WI in 2021......kind of unnerving at 1:00 a.m. But, it didn't stop working. I put a new lifetime alternator from Carquest and the flickering stopped. Been 50k miles and no issues.

But, as others have suggested, cleaning the connections is a good practice and, based on your pictures, was worthwhile.

Three different alternators. Same problem.

 

[solli5pack]

So I checked all the grounds in the engine compartment and so far everything is testing good. I need to get to the ones behind the bumper and check those next but it's hot as hell right now in Jersey so might wait a few days. Also swapped batteries from the Suburban and the issue remains. I have all the wiring diagrams and ground locations printed from All Data and eventually I'm gonna check everything until I find this Gremlin! I'm also eyeing up the headlight switch since everything that's flickering seems to run through it. Like I said I believe this truck spent it's previous life living at the Jersey Shore so quite a bit of rust and corrosion to work through.

 

[Doubeleive]

So I checked all the grounds in the engine compartment and so far everything is testing good. I need to get to the ones behind the bumper and check those next but it's hot as hell right now in Jersey so might wait a few days. Also swapped batteries from the Suburban and the issue remains. I have all the wiring diagrams and ground locations printed from All Data and eventually I'm gonna check everything until I find this Gremlin! I'm also eyeing up the headlight switch since everything that's flickering seems to run through it. Like I said I believe this truck spent it's previous life living at the Jersey Shore so quite a bit of rust and corrosion to work through.

headlight switch is not a bad idea, you could try unplugging the rvc module to see if that makes any difference also. that is the clamp looking module that is on the ground cable connected to the battery, unplugging it will not cause any problem.
if all else fails you can try adding a ground to the light circuit in the past this has helped myself and others, the light circuit has been known to have a poor ground.
you might want to take a look at the fuse box too for corrosion.