Gen 2 light starts flickering after truck is warmed up

dsouthwick54

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WILLITS CA
I have good readings at both alternators and batteries, new belts properly tightened. Gen 1 and 2 lights both come on when I turn key one click. After starting the truck both lights go off. After truck warms up (about 2 or 3 minutes) the GEN 2 light starts flickering faintly ( not full brightness as when I turned key one click) . When it does, I check voltage at both alternators, both batteries, and there is no change In voltage. However, when I check the voltage at Gen 2 diode, it’s jumping from 29 down to 25 and everywhere in between. ( I also checked diode when Gen 2 light doesn’t flicker and it remains 29) This is the only place I’ve found the voltage change. Can anyone help? Thank you
 

Skinny

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Does the light go out if you increase RPM ever so slightly? Sometimes low idle will cause flicker. Bad regulators will also do this too. Have they ever been rebuilt? Skipping belt at low speed can do this too.
 

dsouthwick54

New member
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Location
WILLITS CA
Does the light go out if you increase RPM ever so slightly? Sometimes low idle will cause flicker. Bad regulators will also do this too. Have they ever been rebuilt? Skipping belt at low speed can do this too.
The light actually increases with flashing and brightness with increased rpms. Yes I rebuilt them both twice. Sounds like it could still be a bad regulator though?
 

cucvmule

collector of stuff
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Check all connections at the alternators, making sure none are breaking at the eyelets. Firewall bussbars, clean connections.

How old are your batteries? Have you checked each individual cell for charge with hydrometer?

Check wires for chaffing and possible corrosion at any bare spots.

Check, clean grounds, doing easy simple checks eliminates some issues.
 

dsouthwick54

New member
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Location
WILLITS CA
Have you considered taking them off and having them tested at a competent alternator shop? I always say there is more to rebuilding components then putting a few parts in. Do it right the first time and drive on. Cheaper is NEVER better. Good Luck.
Yes. I know I thing or two about rebuilding alternators thank you. I didn’t go the cheap route. Both alternators are fine. It was a belt slipping
 

Skinny

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Yes. I know I thing or two about rebuilding alternators thank you. I didn’t go the cheap route. Both alternators are fine. It was a belt slipping
Damn v-belts...mine seems to loosen up every once in awhile. That's funny that your charge light flickered before the belt started to squeal. If only the other dummy lights in a CUCV worked that good 🤣
 

Keith_J

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Schertz TX
I've made a 27SI testing rig using a spare plug, a light bulb and an alligator clip. Use a good battery, chuck the alternator in a vise and spin it up with a drill and socket wrench.
 
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