All lights flicker when running

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Phreakish said:
I've seen this before when a diode or two popped in the alternator. Ac voltage causes the flicker. Rare, but happens.

A swap with a know good or remove it and have it tested, though I've seen bad alts pass the typical bench check.

It's also possible to disconnect the field and positive wire from the alt to see if it goes away - problem is that this test doesn't rule out the regulator. Alternator problems can be tough to diagnose.
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All disabling the alternator does is to prove what we already know.....that this is caused from action by the alternator. Doing so does NOT tell us where or what is actually wrong.
 
67Dart273 said:
All disabling the alternator does is to prove what we already know.....that this is caused from action by the alternator. Doing so does NOT tell us where or what is actually wrong.
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Pretty much what I said in my disclaimer. But it would rule out something else outside the charging system causing a cyclic drain and confirm it's in the alternator or regulator.

It's not likely to be outside the charging system, but stranger things happen.

The alternative is to test for ac voltage, and not everyone has the tools or ability to do so. If it is a diode, no number of ground straps or new regulators will fix it.
 
I've never seen AC do this but I guess it could. So far as testing, all you need is a multimeter, and EVERY car owner who does their own work should HAVE one. Simply put the meter on AC volts while the car is running / charging, and check the alternator output stud. This will give you the ripple voltage. I don't remember what the "accepted" published limit is, but it will be WAY below 1/2 volt AC

assets.fluke.com/appnotes/automotive/beatbook.pdf
 
67Dart273 said:
I've never seen AC do this but I guess it could. So far as testing, all you need is a multimeter, and EVERY car owner who does their own work should HAVE one. Simply put the meter on AC volts while the car is running / charging, and check the alternator output stud. This will give you the ripple voltage. I don't remember what the "accepted" published limit is, but it will be WAY below 1/2 volt AC

assets.fluke.com/appnotes/automotive/beatbook.pdf
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Agreed. Anyone who owns a wrench should have both an analog and digital multimeter.

Some dmms have problems reading ac and DC together. Better meters like fluke can do it, but when they're not setup for it, an extra external capacitor is needed. It's often a check that is beyond the average persons capabilities.. But the good news is that if the meter reads low (.6v max) then it shouldn't be the problem. If it reads way high (over 1-2v) then it's likely the meter and proves nothing. This is why a bench test on a vehicle that so easy to yank the alternator from is often easier.

I've had a single diode have issues that caused exactly this for a short time until it caused enough further trouble/damage that it caused a problem that was obviously the alternator and replacing it fixed the problem.

Fun part was that something in the failing diode pack (heat, most likely) lead to an internal field short that skyrocketed my voltage. My reaction? Hit the emergency flashers and pull over. The result? Every light bulb in that car went "poof".
 
I will pull the alternator and get a second opinion. I do have both types multimeters, been used a lot..... Thanks for all the input!!!
 
2x on bad diode or two. The alternator is a 3 phase unit, loss of one part in phase results in dip, the regulator responds, but is too late, so over voltage with next phase...regulator then see dip.... bumpy voltage, hence flashing lights.

A scope helps trouble shoot that problem.
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The diodes flip the negative section, so the the result is a series of humps. Imagine a missing hump, or complete phase loss. The dip, is not corrected by regulator correctly because the next hump is good, that is where over voltage happens.

The earlier mechanical regulator exhibit more flicker. The electronic regulators are faster, and may mask diode problems, and a few are driving with bad diodes and do not notice.
 
Kinda having the same issue on my son's Valiant. Any links or names of these electronic regulators being mentioned?
 
"E" Bay has them, just be careful you get one for your car....
 
coalman said:
"E" Bay has them, just be careful you get one for your car....
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Ebay is the last place I'd look, unless you find NOS. You want an older NOS Chrysler (OEM) or NAPA (Echlin) or Standard / Blue Streak. The ones sold at the parts stores, I don't know anymore. Crap shoot.
 
I am going to get another Alternator, 60 amp or 50 amp OK??? Thanks
 
Have you tried the regulator yet? I would start there. This is assuming the wiring is good.
 
Yes it has a new transistorized regulator, also purchased a rebuilt alternator, really helped a lot. There still a little flux on the cars voltmeter. I am going to do a ohms check from the alternator through the bulkhead to starter relay and see what I get. Thanks again for all the input.....
 
Just remove the disco chip! ;) I was thinking rectifier issues as mentioned above... Marginal or weak diodes. Update to a square back alternator and newer style regulator will usually stop the original problem but then the original wiring is sub standard for the new output....
 
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