All Lights Flickring (pulsating)

krazycold · December 20, 2009

Hi everyone, I am new to this site, has anyone had this same problem with the lights.I have 2001 GMC Z71 with approx 147,000 km on it. Have noticed for a while now that the lights pulsate or flicker at idle and above. Tried everything as far as i can go without taking it to the dealer. dealer where i live not fit. Have changed alternator battery checked and cleaned all ground also added a ground from battery to vehicle body. Still with the same result. bought factory alternator and battery no after market stuff. Reason for the post is because i would like to install an hid headlight kit but with this pulsating (flickering) i am unsure how this will effect the ballast and what not. just a side note i am an apprentice heavy duty mechanic so have some ability to repair issue if a solution is given. Thank you guy's for checking out this post. any and all suggestions is appreciated.

salden77 · December 21, 2009

Hi everyone, I am new to this site, has anyone had this same problem with the lights.I have 2001 GMC Z71 with approx 147,000 km on it. Have noticed for a while now that the lights pulsate or flicker at idle and above. Tried everything as far as i can go without taking it to the dealer. dealer where i live not fit. Have changed alternator battery checked and cleaned all ground also added a ground from battery to vehicle body. Still with the same result. bought factory alternator and battery no after market stuff. Reason for the post is because i would like to install an hid headlight kit but with this pulsating (flickering) i am unsure how this will effect the ballast and what not. just a side note i am an apprentice heavy duty mechanic so have some ability to repair issue if a solution is given. Thank you guy's for checking out this post. any and all suggestions is appreciated.

i installed HID lows and highs in my truck over the summer and i have flickering headlights, dash lights, if it lights up it flickers, the reason mine flicker is because i have over 2000 watts of aftermarket stereo equipment in my truck, i installed the HIDs anyways because mine came with a 2 year warranty for the ballasts and the lamps and they were only 50 for the whole kit anyways so i figured i would try it, i can turn my stereo all the way up to point that i cant even hear myself think and my whole truck is vibrating and the HIDs wont dim on me at all. also when hooking up HIDs make sure your existing headlight wiring isnt reverse polarity, you may have to switch the wires around for the input to your ballast, and check your headlight fuses and upgrade them to 20 amp fuses if they arent already because the ballast has a high inrush when you first turn the lights on.

denali503 · December 23, 2009

if you are having only parking and cabin lights flicker, might want to check the grounding circuit for the switch or check the relay for the lights...

You could also check the schem for the truck to see if there is a seperate voltage regulator or if it is built into the alternator. I have seen some vehicles where the voltage regulator is separate from the alternator for some reason.

other than that you got me

krazycold · December 24, 2009

Hi everyone, I am new to this site, has anyone had this same problem with the lights.I have 2001 GMC Z71 with approx 147,000 km on it. Have noticed for a while now that the lights pulsate or flicker at idle and above. Tried everything as far as i can go without taking it to the dealer. dealer where i live not fit. Have changed alternator battery checked and cleaned all ground also added a ground from battery to vehicle body. Still with the same result. bought factory alternator and battery no after market stuff. Reason for the post is because i would like to install an hid headlight kit but with this pulsating (flickering) i am unsure how this will effect the ballast and what not. just a side note i am an apprentice heavy duty mechanic so have some ability to repair issue if a solution is given. Thank you guy's for checking out this post. any and all suggestions is appreciated.

Hi thanks for answering the question for the hid lights. I ordered a low beam hid kit. Don't see the point yet in ordering a high beam kit as i don't drive that much at night for long distances and always to much traffic besides.

krazycold · December 24, 2009

if you are having only parking and cabin lights flicker, might want to check the grounding circuit for the switch or check the relay for the lights...

You could also check the schem for the truck to see if there is a seperate voltage regulator or if it is built into the alternator. I have seen some vehicles where the voltage regulator is separate from the alternator for some reason.

other than that you got me

Hi thanks for the insight into what to check next as i would not have thought of the switch wires and separate voltage regulator for the alt. That may explain a bit of the dip in lights when i let of the throttle some times. great advice will get back to you with the results.

denali503 · December 24, 2009

One more thing i just thought of... although it's unlikely to be the culprit but sucks when it is since it's generally a cheap fix.

Being 10 years new (almost) I would check the resistance between the neg battery terminal to the block, to the frame, etc. There is a small possibility that there is some corrosion under one of the grounding straps, or corrosion in the grounding strap causing a bad ground, the most obvious place you would see it would be in the lighting, but it could cause a different voltage potential for much of the equipment.

While you are in there, i'm not too familiar with the GM pos voltage fromthe alt wiring, but i know many imports go straight to the battery terminal and out from there. If there is some corrosion on that line or too much interference, the same issue could occur

krazycold · December 25, 2009

One more thing i just thought of... although it's unlikely to be the culprit but sucks when it is since it's generally a cheap fix.

Being 10 years new (almost) I would check the resistance between the neg battery terminal to the block, to the frame, etc. There is a small possibility that there is some corrosion under one of the grounding straps, or corrosion in the grounding strap causing a bad ground, the most obvious place you would see it would be in the lighting, but it could cause a different voltage potential for much of the equipment.

While you are in there, i'm not too familiar with the GM pos voltage fromthe alt wiring, but i know many imports go straight to the battery terminal and out from there. If there is some corrosion on that line or too much interference, the same issue could occur

krazycold · December 25, 2009

One more thing i just thought of... although it's unlikely to be the culprit but sucks when it is since it's generally a cheap fix.

Being 10 years new (almost) I would check the resistance between the neg battery terminal to the block, to the frame, etc. There is a small possibility that there is some corrosion under one of the grounding straps, or corrosion in the grounding strap causing a bad ground, the most obvious place you would see it would be in the lighting, but it could cause a different voltage potential for much of the equipment.

While you are in there, i'm not too familiar with the GM pos voltage fromthe alt wiring, but i know many imports go straight to the battery terminal and out from there. If there is some corrosion on that line or too much interference, the same issue could occur

Hi rick noticed today or should i say this morning if i push on the brake pedal the pulsating(flickering) stops not to sure what to think of that maybe i was just to tired to believe it!!! lol i will look into the grounds again never know. I live in a place were we do not salt the roads in the winter. It just freezes to the ground so we have little to no rust or corrosion issues. But will look into the issue thanks again and merry Christmas to you and your family

minibike132 · December 28, 2009

Being 10 years new (almost) I would check the resistance between the neg battery terminal to the block, to the frame, etc. There is a small possibility that there is some corrosion under one of the grounding straps, or corrosion in the grounding strap causing a bad ground,

Checking resistance is next to useless when checking almost any circuit. Google automotive voltage drop and perform a voltage drop on any circuit you want to verify.

krazycold · December 28, 2009

Being 10 years new (almost) I would check the resistance between the neg battery terminal to the block, to the frame, etc. There is a small possibility that there is some corrosion under one of the grounding straps, or corrosion in the grounding strap causing a bad ground,

Checking resistance is next to useless when checking almost any circuit. Google automotive voltage drop and perform a voltage drop on any circuit you want to verify.

Just another thought has anyone ever had an issue with the automatic turn on sensor for the headlights or am i just fishing in the dark. is it possible that the light sensor does not know on from off and maybe failing. Will keep searching for the true problem if it exists. or was it just a built in factory item to annoy the costumer but would not trade it in for that other junk....!!!!!!