lights pulsate
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Elder User
Joined: Sep 2008
Posts: 563
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From: DeKalb, Ill.
lights pulsate
I found a thread here within the past week that someone else had posted- same problem, I can't find the thread now and was wondering what the cause was. I'm aware that it's likely a ground issue and plan to clean all of the contacts after work tomorrow. Would be nice if my $1.49 wire brush remedies it! Anyway, if you're out there and you posted the thread I'm referring to, let me know how it turned out.
Thanks, Matt.
Thanks, Matt.
MSEE
Joined: Apr 2004
Posts: 10,386
Likes: 35
From: Austin, TX
Very likely to be a regulator ground issue - make sure you have a good ground strap between the engine block and the firewall. This is how your entire electrical system grounds. The regulator grounds to the inner fenderwell, which bolts to the firewall. If this checks out okay, it's most likely the regulator field relay not switching fast enough. The pulsating headlights is an indication of fluctuating voltage. In that case the regulator should be replaced.
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Elder User
Joined: Sep 2008
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From: DeKalb, Ill.
To sum up answers the questions you have all asked, I'll say that the "flickering" everyone is asking about, I would call it surging, or pulsating, the lights never go away, they just surge from bright to dim. The rhythm of the pulsating is probably about 3 or 4 times per second. It nearly goes away when the truck is at running temp, but not quite all together. Something else I'm not sure about is this "regulator", where exactly is this piece?
Help me out if you find time.
Thanks in advance,
Matt.
Help me out if you find time.
Thanks in advance,
Matt.
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MSEE
Joined: Apr 2004
Posts: 10,386
Likes: 35
From: Austin, TX
The regulator is a small square box about the size of a hockey puck and is on the passenger side inner fenderwell, usually past the starter solenoid. Its job is to regulate the system voltage to 13-14 volts by essentially enabling and disabling the alternator.
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Joined: Nov 2008
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From: Halifx Pa
Funny, I just recently started to notice this on my dent. Your right Murph, it pulsates, not goes out and back on. I didn't notice in the head light, but I did on the dome and registration lights. I do have ground strap that I been wanting to pull of and buff it up with a wire brush, under the hood. I have no clue how long the alternator has been on, and the voltage regulator on the outside of it is so rusted, you can't see most of the blue paint that was on it. And sorry Murph, I didn't mean to jump your thread, but I was wondering about this too! Oh yeah, my regulator is beside the radiator, passenger side.
Posting Guru
Joined: Nov 2008
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From: Halifx Pa
So today I went out and cleaned the negative cable where it connects to the block, and the ground strap near the back. I also pulled the voltage rugulator off and and took the wire brush to all of that and pulled the plug out and sprayed electrical contact and spray lub on all connections, ground straps too.
I fired it up and it still did it, then I shut it off and then started it up and no more pulsating, or surging. Now that just seemed way to easy. I am not 100% sold it won't rear it's ugly head again. If it does I guess I'll take the alternator to the parts store for a test and if that is good, I'll focus on the regulator.
I fired it up and it still did it, then I shut it off and then started it up and no more pulsating, or surging. Now that just seemed way to easy. I am not 100% sold it won't rear it's ugly head again. If it does I guess I'll take the alternator to the parts store for a test and if that is good, I'll focus on the regulator.
MSEE
Joined: Apr 2004
Posts: 10,386
Likes: 35
From: Austin, TX
Chances are you fixed it. The reason I suggest the ground issue is because as the ground strap and wiring is subjected to environmental elements, the ground seen by the regulator "shifts" and does not see a true zero volts, but a volt or two higher. This gives the regulator a false reading and it cannot properly maintain the system voltage. But if you do see the problem again in the near future, your method sounds reasonable.
More Turbo
Joined: Aug 2007
Posts: 555
Likes: 2
From: Washington state
I would also advise adding a ground wire from the Alternator case to the truck frame. I have seen the wire they use to ground from the motor to the fire wall and all I can say is that it's a punny little wire.
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Elder User
Joined: Sep 2008
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From: DeKalb, Ill.
Thanks for all of the great help. I planned on getting those connections cleaned today after work but I won't get to it. Unfortunately, first thing's first. Nights are getting cold here in northern Illinois, since I just bought the truck I need to flush the coolant and make sure the mix is right, it will be in the 20's and teens at night starting tonight. Soonest I can tackle the ground issue is Sunday, I'll keep you posted. Thanks, Matt.
Oh, and Tees, don't apologize for anything, you only helped.
Oh, and Tees, don't apologize for anything, you only helped.
Senior User
Joined: Dec 2007
Posts: 206
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From: Good Hope, GA
I have found that the mechanical regulators do this. I have several and at idle(depends on how low your truck idles) some will actually make the lights brighter then off idle they will dim slightly, sometimes they will just kinda "flicker" not even close to going out, but almost unnoticeably dimming and coming back.
The replacement electronic regulators will make all the flashing and flickering go away.
The replacement electronic regulators will make all the flashing and flickering go away.
Posting Guru
Joined: Nov 2008
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From: Halifx Pa
OK, cool Murph, to bad you don't have a garage to keep the ol'girl in. I know my 77, she earned herself a spot in the garage, she doesn't set in the cold, or rain, and snow anymore if I cane help it. Actually her hailin days are about over too except for some bags of bark mulch, a case of beer, or groceries.
Also, fmc400, THANKS for your help, I noticed you given plenty of good clear concise help with our dents. Maybe you should chang your name to the the dentdoctor, or something like that. I think I will have to click on the add to your reputation botton! Thanks again bro!
P.S. fmc, I like your dent, I rember those coming through the dealership when I was working there as a young lad back in the day.
Also, fmc400, THANKS for your help, I noticed you given plenty of good clear concise help with our dents. Maybe you should chang your name to the the dentdoctor, or something like that. I think I will have to click on the add to your reputation botton! Thanks again bro!
P.S. fmc, I like your dent, I rember those coming through the dealership when I was working there as a young lad back in the day.