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sprinkles08
sprinkles08, ASE Certified Technician
Category: Car
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Experience:  ASE Master and Advanced level certified. Factory trained with 15 years dealership experience
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GMC Sierra 2500 HD: You repliedThursday, January 31, 2013

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You replied
Thursday, January 31, 2013 7:33 PM CST
Ok I'm still having the issue with my lights flickering. I've replaced the starter and ground wires. When I'm idling it doesn't flicker. It only seems to happen when I'm driving and set my cruise anywhere between 50mph and 70. And it also happens on smooth roads and doesn't seem to be caused from bumps or vibration. I'm stumped on this!



You replied
Thursday, January 31, 2013 7:33 PM CST
Ok I'm still having the issue with my lights flickering. I've replaced the starter and ground wires. When I'm idling it doesn't flicker. It only seems to happen when I'm driving and set my cruise anywhere between 50mph and 70. And it also happens on smooth roads and doesn't seem to be caused from bumps or vibration. I'm stumped on this!




You replied
Thursday, January 31, 2013 7:33 PM CST
Ok I'm still having the issue with my lights flickering. I've replaced the starter and ground wires. When I'm idling it doesn't flicker. It only seems to happen when I'm driving and set my cruise anywhere between 50mph and 70. And it also happens on smooth roads and doesn't seem to be caused from bumps or vibration. I'm stumped on

You replied
Thursday, January 31, 2013 7:33 PM CST
Ok I'm still having the issue with my lights flickering. I've replaced the starter and ground wires. When I'm idling it doesn't flicker. It only seems to happen when I'm driving and set my cruise anywhere between 50mph and 70. And it also happens on smooth roads and doesn't seem to be caused from bumps or vibration. I'm stumped on this!
Hi,

I'm a moderator for this topic. I've been working hard to find a Professional to assist you right away, but sometimes finding the right professional can take a little longer than expected.

I wonder whether you're ok with continuing to wait for an answer. If you are, please let me know and I will continue my search. If not, feel free to let me know and I will cancel this question for you.

Thank you!
Customer: replied 3 years ago.
Yes I will wait. I've been waiting for two days now!
There are a few other things it could be besides grounds. I'm assuming all ground points and cables have been ruled out.

It could be an issue on the positive side of the system. If there is corrosion at a connection at alternator or anywhere on it's output then it can cause the lights to flicker. One thing that is often helpful is running a jumper to see if the problem goes away, but that may be harder to safely accomplish in your case. For instance if you can safely run a jumper cable or large gauge jumper wire from the alternator to the positive battery post and the problem goes away then you know the problem is in the positive cable somewhere.

It could also be the alternator itself. An erratic output from the alternator will cause the lights to flicker. What you could do is disable the alternator while it's acting up and if the problem goes away, assuming the cables are good, then you know it's the alternator.
Customer: replied 3 years ago.
Ok, not sure if this would you at all, but I've noticed that this doesn't happen unless the rpm's get above 2000. Maybe the alternator is bad? It's only about a month old but I guess it could be a bad one. It almost seems to be charging to much.
Correct, it sounds like there is electrical noise coming from the charging system or it's overcharging. The fact that it happens over 2,000 RPM's makes more of a case for a charging system issue.
Customer: replied 3 years ago.
So do you think I should just replace it or is some voltage test that I can try first? If so, what readings should I get?
You can either try replacing it or disable it and drive it to see if the problem goes away.
sprinkles08, ASE Certified Technician
Category: Car
Satisfied Customers: 21591
Experience: ASE Master and Advanced level certified. Factory trained with 15 years dealership experience
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