Electrical - where to begin

[Moosemoon]

Good baseline to start from. At least you won't be chasing all other systems forever, only to find out problems were chassis grounds!

I am sure the expert electrical gurus will get you figured out pretty quickly.

Thanks I hope so.

 

[S33k3r]

I'm SO sorry I am getting to this late, but it sounds like you are experiencing an alternator failure. That is one of the few things that would cause issues with all these electrical systems at once. The alternative, of course, is that something the mechanic did or it sitting for so long took out multiple systems. But the fact no one can find anything wrong leads me to look at the alternator.

Additionally, we had some issues with a bunch of subsystems on my Wife's Suburban; it turned out the cables going to the ECM were rusted; they were either broken or the resistance was so high current wasn't flowing. But she had driven through some high water on a 1000 year rain day.

I wish you were down here -- I could suggest a GOOD, HONEST mechanic you could take it to.

***** EDIT: If you get the chance, please share some pictures of your rig.

 

[Doubeleive]

I'm SO sorry I am getting to this late, but it sounds like you are experiencing an alternator failure. That is one of the few things that would cause issues with all these electrical systems at once. The alternative, of course, is that something the mechanic did or it sitting for so long took out multiple systems. But the fact no one can find anything wrong leads me to look at the alternator.

Additionally, we had some issues with a bunch of subsystems on my Wife's Suburban; it turned out the cables going to the ECM were rusted; they were either broken or the resistance was so high current wasn't flowing. But she had driven through some high water on a 1000 year rain day.

I wish you were down here -- I could suggest a GOOD, HONEST mechanic you could take it to.

***** EDIT: If you get the chance, please share some pictures of your rig.

if this was the issue there would be a variety pack of codes and issue's and this is simply not the case. there is a airbag code, knock sensor code, and fuel pressure/level issue.
most likely not related to the alternator.
if there was low voltage you would see all kinds of stuff going on or not working period.

 

[S33k3r]

if this was the issue there would be a variety pack of codes and issue's and this is simply not the case. there is a airbag code, knock sensor code, and fuel pressure/level issue.
most likely not related to the alternator.
if there was low voltage you would see all kinds of stuff going on or not working period.

Had this happen with a buddy's Yukon XL 2500. It absolutely was the alternator. This kind of crap CAN happen from a dying alternator. Could also be the power cable running between the alternator and the battery. I've heard of that thing rusting within the insulation and causing issues.

Note that, at least some of the problems CAN be caused by a weak or dying alternator. Because she's had someone else's hands in this vehicle and it sat for 2 years, it is most likely a combination of headaches. But I believe it won't hurt to test the alternator.

 

[Doubeleive]

Had this happen with a buddy's Yukon XL 2500. It absolutely was the alternator. This kind of crap CAN happen from a dying alternator. Could also be the power cable running between the alternator and the battery. I've heard of that thing rusting within the insulation and causing issues.

Note that, at least some of the problems CAN be caused by a weak or dying alternator. Because she's had someone else's hands in this vehicle and it sat for 2 years, it is most likely a combination of headaches. But I believe it won't hurt to test the alternator.

not impossible but normally if this was the case there would be other issue's, certainly could not hurt to verify 13.4v minimum to the battery with engine running.

 

[Baja_Bob]

could not hurt to verify 13.4v minimum to the battery with engine running.

This alternator could put out 13.4v needed, but it actually needs a current test also. Too much or too little current will cause problems to sensitive circuits like these.

 

[Doubeleive]

This alternator could put out 13.4v needed, but it actually needs a current test also. Too much or too little current will cause problems to sensitive circuits like these.

having owned multiple gmt800's for over a decade I have doubts that it is the alternator, certainly cannot hurt to rule it out but I think it's a goose chase.

 

[afpj]

For the alternator idea, it's not enough to check voltage. At this age, cold have rectifier giving out, with some ac ripple getting through intermittently.

 

[S33k3r]

For the alternator idea, it's not enough to check voltage. At this age, cold have rectifier giving out, with some ac ripple getting through intermittently.

Could you please restate that with smaller words? I do not understand your response.

 

[afpj]

As you wish....For the alternator idea, it's not enough to check voltage. At this age, cold have rectifier giving out, with some ac ripple getting through intermittently


Our system is 12 VDC. If any AC voltage/current is let out because the rectifier is failing, the DC rated components behave badly, like all sorts of unrelated codes, potentially (like bad grounds)