Light flickering
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Joined: Sep 2015
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Light flickering
Hey all,
I know the light flickering issue has been talked about, but mine seems a bit different. So I have a new voltage regulator and my alt is good. Batt is good as well. So when I replaced my voltage regulator originally the flickering stopped. The flickering recently started again,but after about 5-10 minutes of the engine running. I thought maybe it was a fluke, but its continuing to do it. Truck is a 74 250 with a 360.
Thanks in advance for any info!
I know the light flickering issue has been talked about, but mine seems a bit different. So I have a new voltage regulator and my alt is good. Batt is good as well. So when I replaced my voltage regulator originally the flickering stopped. The flickering recently started again,but after about 5-10 minutes of the engine running. I thought maybe it was a fluke, but its continuing to do it. Truck is a 74 250 with a 360.
Thanks in advance for any info!
Post Fiend
Joined: Apr 2002
Posts: 19,311
Likes: 97
From: Waterloo, Iowa
Have you measured the voltage while it's flickering? By definition it's a regulation problem, the question is what's causing it.
My WAG is neglected grounds, or specifically the ground reference of the regulator itself must be at the same potential as the alternator and battery, all three. If it's "floating" with respect to these it's going to want to go high side. Where is it mounted? Try another heavy jumper wire from regulator case to alternator itself, clean unpainted spot. See if the problem goes away. A related problem is old engine, frame, and firewall ground and starter battery cables etc. These will kill alternator efficiency. If they are even close to original replace them on general principles. Trust Me.
My WAG is neglected grounds, or specifically the ground reference of the regulator itself must be at the same potential as the alternator and battery, all three. If it's "floating" with respect to these it's going to want to go high side. Where is it mounted? Try another heavy jumper wire from regulator case to alternator itself, clean unpainted spot. See if the problem goes away. A related problem is old engine, frame, and firewall ground and starter battery cables etc. These will kill alternator efficiency. If they are even close to original replace them on general principles. Trust Me.
Thread Starter
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New User
Joined: Sep 2015
Posts: 8
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Have you measured the voltage while it's flickering? By definition it's a regulation problem, the question is what's causing it.
My WAG is neglected grounds, or specifically the ground reference of the regulator itself must be at the same potential as the alternator and battery, all three. If it's "floating" with respect to these it's going to want to go high side. Where is it mounted? Try another heavy jumper wire from regulator case to alternator itself, clean unpainted spot. See if the problem goes away. A related problem is old engine, frame, and firewall ground and starter battery cables etc. These will kill alternator efficiency. If they are even close to original replace them on general principles. Trust Me.
My WAG is neglected grounds, or specifically the ground reference of the regulator itself must be at the same potential as the alternator and battery, all three. If it's "floating" with respect to these it's going to want to go high side. Where is it mounted? Try another heavy jumper wire from regulator case to alternator itself, clean unpainted spot. See if the problem goes away. A related problem is old engine, frame, and firewall ground and starter battery cables etc. These will kill alternator efficiency. If they are even close to original replace them on general principles. Trust Me.
Thanks again!
FTE Leadership Emeritus
Joined: Jul 2002
Posts: 42,561
Likes: 421
From: Long Island USA
The stock alternators in these vehicles are lucky to put out 40amps (or even 30) max, and at idle, they are barely enough to keep a GOOD battery charged.
The flicker might be a bad diode (or more than one) in the alternator. The alternator will "test good" on the bench, because it'll put out enough voltage to be within spec, but one bad diode will cause the voltage coming out of it to have a "ripple" and can drive the regulator nuts.
Is it the old big "thick" regulator, or a newer thin style? The thick regulator actually has mechanical relays in it, and the contacts can get worn from arcing.
The flicker might be a bad diode (or more than one) in the alternator. The alternator will "test good" on the bench, because it'll put out enough voltage to be within spec, but one bad diode will cause the voltage coming out of it to have a "ripple" and can drive the regulator nuts.
Is it the old big "thick" regulator, or a newer thin style? The thick regulator actually has mechanical relays in it, and the contacts can get worn from arcing.
Thread Starter
|
New User
Joined: Sep 2015
Posts: 8
Likes: 0
The stock alternators in these vehicles are lucky to put out 40amps (or even 30) max, and at idle, they are barely enough to keep a GOOD battery charged.
The flicker might be a bad diode (or more than one) in the alternator. The alternator will "test good" on the bench, because it'll put out enough voltage to be within spec, but one bad diode will cause the voltage coming out of it to have a "ripple" and can drive the regulator nuts.
Is it the old big "thick" regulator, or a newer thin style? The thick regulator actually has mechanical relays in it, and the contacts can get worn from arcing.
The flicker might be a bad diode (or more than one) in the alternator. The alternator will "test good" on the bench, because it'll put out enough voltage to be within spec, but one bad diode will cause the voltage coming out of it to have a "ripple" and can drive the regulator nuts.
Is it the old big "thick" regulator, or a newer thin style? The thick regulator actually has mechanical relays in it, and the contacts can get worn from arcing.
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