I had an issue similar with flickering lights. Headlights and interior lights would flicker all the time. The service charging system would come on from time to time but never for very long. I had the alternator tested at oreilly's and it came back good. Luckily one day I was passing an oreilly's as the service charging message appeared and the battery light was on. They tested the alternator again, it was bad. Replaced it with a new one. No more problems with flickering lights after that.
Lights flickering
- Thread starter mattah
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gtp1500
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So far I haven't had the warning but I'm sure the alternator needs to be my next move.
Just hard to get myself to buy one when I'm charging although it will on occasion drop to 11.7ish for short periods of time but reading how these things charge it doesn't seem abnormal.
Just hard to get myself to buy one when I'm charging although it will on occasion drop to 11.7ish for short periods of time but reading how these things charge it doesn't seem abnormal.
gtp1500
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- Feb 21, 2016
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I replaced the alternator and have nice steady lights!
Also the engine doesn't surge or idle rough now either.
Also the engine doesn't surge or idle rough now either.
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Sorry to bring this topic back up from the dead, but I have a similar issue - headlights, brake lights, and dome lights dimming from a cold start only. They stop dimming after 10-30 minutes of driving.
I've used a multimeter on both the battery and alternator under both conditions
Battery while lights dimming: 12-14v
Battery while lights steady: 12-14v
Alternator while lights dimming: 3-4v
Alternator while lights steady: 11-14v
So I think it's the alternator, but one thing that's giving me pause is that it was replaced recently. January 2016, per the Carfax, just a few months before I bought the Suburban, and it does look new. Of course it's entirely possible that the replacement alternator is defective. I took the S-belt off and spun the pulley, there is no play or noise.
Before I spend the money on another new alternator, does anyone have any suggestions? Thanks!
Edit: I took the plunge and bought a new alternator for $150. It fixed my problem - the old alternator was putting out inconsistent voltage.
For what it's worth, I bought a 160 amp because I had an RPO that called for one. I have no way of telling for sure but I suspect the old one was a 145 amp.
I've used a multimeter on both the battery and alternator under both conditions
Battery while lights dimming: 12-14v
Battery while lights steady: 12-14v
Alternator while lights dimming: 3-4v
Alternator while lights steady: 11-14v
So I think it's the alternator, but one thing that's giving me pause is that it was replaced recently. January 2016, per the Carfax, just a few months before I bought the Suburban, and it does look new. Of course it's entirely possible that the replacement alternator is defective. I took the S-belt off and spun the pulley, there is no play or noise.
Before I spend the money on another new alternator, does anyone have any suggestions? Thanks!
Edit: I took the plunge and bought a new alternator for $150. It fixed my problem - the old alternator was putting out inconsistent voltage.
For what it's worth, I bought a 160 amp because I had an RPO that called for one. I have no way of telling for sure but I suspect the old one was a 145 amp.
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Just picked up our second NNBS Denali and experienced the problem tonight with dome and headlights. Battery is new as of this week by the seller. Is this an alternator issue?
Had the problem in my wife's 08 and went through 2 alternators before it seemed to settle out.
Safe to assume the new one needs an alternator? It's under a 3mo/3k mile bumper to bumper warranty so they can pay for a new AC Delco unit!
Had the problem in my wife's 08 and went through 2 alternators before it seemed to settle out.
Safe to assume the new one needs an alternator? It's under a 3mo/3k mile bumper to bumper warranty so they can pay for a new AC Delco unit!
I have been noticing the lights dim quite a bit when I brake and get a little brighter when I accelerate.
I have sluggish start ups as well.
I had my battery checked by two different places, one said it was bad one said it was good.
Should I replace both the battery and the alternator?
I have sluggish start ups as well.
I had my battery checked by two different places, one said it was bad one said it was good.
Should I replace both the battery and the alternator?
Have them check the alternator over the battery. Also, on single battery trucks, use the 140/145A (whichever one it is) over the 160A. I've had over-charging issues along with warning lights going off. Switched to the lower one and now no issues.
