Pulsing headlights?

My father and I have had no luck trying to trobleshoot the, what its now reffered to as "The light show at 70mph" the head lights begin to "pulse" when you press the brake pedle or the accerator pedle. It even occors when the engine shifts down going up a steep grade. Some times when waiting at a stop light holding the brake. It seems to be random and is usuly trigired by what I just listed. I think its the ground, my dad thinks the 98' blazer is possesed and needs to be rewired. The wipers, locks and power windows also seem to have a mind of there own. This blazer has locked us out of it before! Then opened the windows! WHATS HAPPENING?

Any ideas will be helpful,
Jake Koons

I have the headlight "flicker" as well. I have never been able to pinpoint it though.

Maybe not relevant but the 2005 Chevy Uplander has a widespread headlight flickering problem that was caused by an alternator that doesn't pump out enough power. The dealers have been fixing this problem by installing a more powerful alternator. Aside from the headlights, the dash lights flickered and it causes all other sorts of wierd electrical problems. While I am not aware of any similar design problem with Blazers, perhaps your particular alternator is the problem.

Sounds just the same as my problem. ALL of the lights on mine flicker. I think I am going to look into a high-amp alternator soon anyway because when I turn on the rear defrost the batt. gauge goes down like I am running a 10,000 watt amp.

The difficultly in diagnosing this type of problem is that it behaves much like a bad voltage regulator, but when you test the voltage regulator, it is working fine.

Sounds like a dead spot in the the alternator wiring.

It does sound like an alternator problem. Can you get it tested at an advance auto or other shop??

I agree with the bad regulator in the alternator theory. I had an 82 Olds that would either light up the sky or barely make the head lights glow. Replace the Alternator.

Yes we have taken it many times to the dealer about this and that, but recently we had all of the power locks replaced due to the thing always locking us out wherever we turn our backs....they claimed it was bad locks, and that there might have been a short, somewhere. We also had diffculity getting the 4-wheel drive to change from 2-wheel drive(the 3 buttons) The A/C also had to be replaced beacuse of, well, a short we think, and it somehow fryed the compresser(it made a "pshrw" sound whenever you tryed to turn on the A/C). Most all of the repairs we have had done to it has invloved electricty. O, except when my dad realy messed up the rear diff. My mom has thought for some time that it had been in a flood, but were not relly sure. I will look into the alternator idea tomorrow. The voltage is good all the time though.

Thanks,
Jake Koons

The Uplander (my wife's car) has a digital voltage display on the driver information center and I drove that van 500 miles one night while the headlights (and everything else) were flickering and the entire time the voltage never dropped below what the owner's manual said was within the low end of the normal range (off the top of my head, I think it was around 13.2 volts). When the dealer put in the more powerful alternator, the problem disappeared.

Ever since I got Mud and water up in my engine compartment last summer My alt whines and and makes a scratchy sound. Also I too have a low power problem. At night if I power the windows up my dash lights and head lights dim. Plus all lights slightly strobe to the sub woofer. Obviously its the alt. Not sure if that helped. Just my 2cents

YOU KNOW WHAT? I think it was the alternator, beacuse I was checking the voltage at various places and found it was lowest at the headlights, and the dome light! The dome light was an easy fix, a couple seconds with my cold heat, and problem solved. The headlights however I could not axcess. The voltage got more erratic as I got closer to the alternator. I also put a quick shot of stuff that is suposed to make the connections better while cleaning them. I don't think it helped any. I was supprised how many screws were loose on the enging bay and and other places, I think I had to tighten 20 some screws. A lot more where missing from their threads. I think you'll be suprised how many there may be on your cars/trucks. But, GirlBear, that water and mud might have caused some corrosion, that might be your problem.