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Dimming Head Lights

Koinz

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Koinz Enthusiast

Koinz

Posted
Posted

Hi guys, Great Forum.

 

I have an 01 Sierra 4x4 and love it. Just turned 118,000.

I recently replaced my battery and noticed now while driving at night that my headlights will dim momentarily, then go bright again. Like the Voltage Regulator is a little flaky.

 

I searched the forum and noticed some stuff on battery cable connections. I'll check that tomorrow.

 

Funny thing is that I can duplicate the problem in the driveway, so maybe I can trace the problem down.

 

Any other suggestions would be helpful. I have a voltmeter with an induction connector for measuring the amperage.

When I replaced the battery, I did check to make sure the alternator was still pumping out the juice and it was so this is taking me a little by surprise.

 

Another question. Is it worth rebuilding the alternator with new brushes and regulator? (if the parts are available).

jrrod2004 Senior Enthusiast

jrrod2004

Posted
Posted

depends on the cost of an altenator....I would say replace the altenator and be done with it.

zibzer Enthusiast

zibzer

Posted
Posted
Hi guys, Great Forum.

 

I have an 01 Sierra 4x4 and love it. Just turned 118,000.

I recently replaced my battery and noticed now while driving at night that my headlights will dim momentarily, then go bright again. Like the Voltage Regulator is a little flaky.

 

I searched the forum and noticed some stuff on battery cable connections. I'll check that tomorrow.

 

Funny thing is that I can duplicate the problem in the driveway, so maybe I can trace the problem down.

 

Any other suggestions would be helpful. I have a voltmeter with an induction connector for measuring the amperage.

When I replaced the battery, I did check to make sure the alternator was still pumping out the juice and it was so this is taking me a little by surprise.

 

Another question. Is it worth rebuilding the alternator with new brushes and regulator? (if the parts are available).

 

check for good ground and make sure those terminals are nice and tight. I know it sounds simple, but sometimes the simple things are often overlooked

ujtruck Enthusiast

ujtruck

Posted
Posted
Hi guys, Great Forum.

 

I have an 01 Sierra 4x4 and love it. Just turned 118,000.

I recently replaced my battery and noticed now while driving at night that my headlights will dim momentarily, then go bright again. Like the Voltage Regulator is a little flaky.

 

I searched the forum and noticed some stuff on battery cable connections. I'll check that tomorrow.

 

Funny thing is that I can duplicate the problem in the driveway, so maybe I can trace the problem down.

 

Any other suggestions would be helpful. I have a voltmeter with an induction connector for measuring the amperage.

When I replaced the battery, I did check to make sure the alternator was still pumping out the juice and it was so this is taking me a little by surprise.

 

Another question. Is it worth rebuilding the alternator with new brushes and regulator? (if the parts are available).

 

The headlight flickering or dimming may be caused by a intermittent low voltage output from engine vibrations. When this occurs, a voltage spike causes the voltage regulator to reset. During the reset, generator output drops to almost zero. This is a known issue with GM cars and the correction involves replacing the alternator.

Koinz Enthusiast

Koinz

Posted
  • Author
Posted
Hi guys, Great Forum.

 

I have an 01 Sierra 4x4 and love it. Just turned 118,000.

I recently replaced my battery and noticed now while driving at night that my headlights will dim momentarily, then go bright again. Like the Voltage Regulator is a little flaky.

 

I searched the forum and noticed some stuff on battery cable connections. I'll check that tomorrow.

 

Funny thing is that I can duplicate the problem in the driveway, so maybe I can trace the problem down.

 

Any other suggestions would be helpful. I have a voltmeter with an induction connector for measuring the amperage.

When I replaced the battery, I did check to make sure the alternator was still pumping out the juice and it was so this is taking me a little by surprise.

 

Another question. Is it worth rebuilding the alternator with new brushes and regulator? (if the parts are available).

 

The headlight flickering or dimming may be caused by a intermittent low voltage output from engine vibrations. When this occurs, a voltage spike causes the voltage regulator to reset. During the reset, generator output drops to almost zero. This is a known issue with GM cars and the correction involves replacing the alternator.

 

 

Thanks Joe. Noticed you're from Scarberia. I used to live in Toronto and had some friends in Scarborough, now live in the US. PA to be exact. I'll do some troubleshooting to see what's going on "voltage and amperage" wise.

Koinz Enthusiast

Koinz

Posted
  • Author
Posted
Hi guys, Great Forum.

 

I have an 01 Sierra 4x4 and love it. Just turned 118,000.

I recently replaced my battery and noticed now while driving at night that my headlights will dim momentarily, then go bright again. Like the Voltage Regulator is a little flaky.

 

I searched the forum and noticed some stuff on battery cable connections. I'll check that tomorrow.

 

Funny thing is that I can duplicate the problem in the driveway, so maybe I can trace the problem down.

 

Any other suggestions would be helpful. I have a voltmeter with an induction connector for measuring the amperage.

When I replaced the battery, I did check to make sure the alternator was still pumping out the juice and it was so this is taking me a little by surprise.

 

Another question. Is it worth rebuilding the alternator with new brushes and regulator? (if the parts are available).

 

The headlight flickering or dimming may be caused by a intermittent low voltage output from engine vibrations. When this occurs, a voltage spike causes the voltage regulator to reset. During the reset, generator output drops to almost zero. This is a known issue with GM cars and the correction involves replacing the alternator.

 

 

Thanks Joe. Noticed you're from Scarberia. I used to live in Toronto and had some friends in Scarborough, now live in the US. PA to be exact. I'll do some troubleshooting to see what's going on "voltage and amperage" wise.

 

 

Well, Went out and double checked the cables and gave them a good wire brushing.

Hooked up my volt/ammeter afterwords and was able to duplicate the problem with the lights on.

 

While it's pushing 40 amps, feathering the throttle. On the decel it will momentarily drop to 0 amps and back up to 40. Can't be good to spike like that.

 

With the lights off, it's pushing a constant 25-30 Amps. Is that normal?

 

Anyone know where to pick up a good, reliable alternator. Truck starts and run's fine for now, but I truly believe in being pro-active when I see a potential problem. I don't want to be stuck on the road somewhere.

04z71steve Enthusiast

04z71steve

Posted
Posted

does it do it when your running the heat? if so i think there was a post on this, my moms 03 does it sometimes, we took it in and they gave us a print out, i guess it's completely normal, it happens so sparingly that we've learned to not even notice it anymore!!

 

steve

Koinz Enthusiast

Koinz

Posted
  • Author
Posted
does it do it when your running the heat? if so i think there was a post on this, my moms 03 does it sometimes, we took it in and they gave us a print out, i guess it's completely normal, it happens so sparingly that we've learned to not even notice it anymore!!

 

steve

 

I guess the heat was on, but notice it more with the Headlights on. I guess any real load on the Alternator can trigger it, but what I saw on the ammeter, it seems like it turns off for a second and then turns back on. As I mentioned, with the lights on, the alternator is pushing out 40 amps steady and then drops to nothing for about a second, then back up to 40. With all the computer stuff on vehicles now-adays, it can't be good. Imagine a power surge going to your Home Theater system in the middle of a storm. That sucks.

ujtruck Enthusiast

ujtruck

Posted
Posted
does it do it when your running the heat? if so i think there was a post on this, my moms 03 does it sometimes, we took it in and they gave us a print out, i guess it's completely normal, it happens so sparingly that we've learned to not even notice it anymore!!

 

steve

 

I guess the heat was on, but notice it more with the Headlights on. I guess any real load on the Alternator can trigger it, but what I saw on the ammeter, it seems like it turns off for a second and then turns back on. As I mentioned, with the lights on, the alternator is pushing out 40 amps steady and then drops to nothing for about a second, then back up to 40. With all the computer stuff on vehicles now-adays, it can't be good. Imagine a power surge going to your Home Theater system in the middle of a storm. That sucks.

 

 

 

To solve this dimming issue 1st thing to do is upgrade the Alternator to better High Quality one, then still dimming, here is the solution, I am also planning to do this:

 

http://www.73-87.com/7387garage/exterior/headlight_relay.htm

 

Please visit that link for more instruction

 

HeadLampRelay81-87Quad.jpg

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