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dim generator light

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4.6K views 6 replies 3 participants last post by  JimM  
#1 ·
Ok, noticed I have a dim generator light on all the time (except when car off).

the battery has 12.4-12.6 volts when off, and 13.6-7 when started, leveling off to 14.0-14.1 after coming up to temp.

Any thoughts on this? I have a one wire alternator, but haven't had a chance to take it off and look at model #'s. The voltage regulator is hooked fine (it would seem).

What do you think would cause the dim generator light? I mean, it is about 1/4 bright vs. full, and is never fully on. Would I just have an alternator type/size mismatch, or could something internally be shot with the alternator etc?

Oh, one other thing, is that the car starts at about 650-700 rpms and is veerry choppy until reaching full temp. I might post this in the engine section, but the ignition is a mallory mech. advance unilite and accel coil. I also have no choke hooked up (100 deg. in my garage cold-AZ!). I have been told that the no choke shouldn't be impacting the setup as much as it is, so do you guys think any of this is related? I might have to start a thread in the engine section, but posted here for now to see if it is related.
 
#2 ·
I have a one wire alternator, but haven't had a chance to take it off and look at model #'s. The voltage regulator is hooked fine (it would seem)
Something is wrong there.... A "ONE WIRE" alternator only has 1 wire, the big red one, the other 2 wires that connect to the reg are not there...

If you have a one wire alternator and still have the regulator connected that is the problem. Disconnect and remove the reg, just let the wires hang.

The one wire alternator does not have the means to light the gen light.

Please clarify this?
 
#3 ·
that is kind of what I was seeing in the posts I was searching through (all night!).

See, it appears to have a two wire white pigtail that is hanging, but is only using one of the wires on it to the alternator (rig job from previous owner). all the wires appear to be on the regulator, but haven't had a chance to tone them out and see what goes where, and didn't want to cut open the harness just yet.

I thought the voltage regulator would still be used with a one wire alternator, but the gen. light would not be a functional light. I don't know if this would make it on all the time or off all the time or what. Or, if the guy bypassed the regulator, but kept it hooked up for looks, I don't know.

Everything appears to be connected how it should be to the untrained eye (me!).

Is there anything specifically I should look for, and do I need to inspect the alternator for part #'s to verify externally regulated or not etc?
thanks!
 
#4 ·
brown, Just pull the numbers off the top of alt to decode. Also, is there a square hole on the back towards the pass side for the plug? If not, then you dont have the correct alt for a 69 (that has not been converted to an internal regulator). On externally reglulated alts, a dim gen light, or one that takes high revs to go out, mean one or more of the internal diodes (there are 4) are dead.
 
#5 ·
Ok, part #'s on the thing are 4J 5-12VNEG 1100560 55A

Seems to be a delco 10si internally regulated alternator? It is one wire, w/ a plastic plug on the other 2 spade terms. From what I can see, the red wire is hooked up, and the white has nothing going to it, and has no voltage.

Should I do the 1-4 splice, 2-3 open (or w/e it is!) on the regulator?

Also, I have just hooked up my vintage air system, and it def. drops the rpms down when it kicks in by about 150-200 rpms, and a couple tenths of volts... do I have a big enough alternator? Runs 13.6 or so and 650-700 rpms when cold started, and 14-14.1 when up to temp with 880-900 rpms warm.

Image
 
#6 ·
ok, unhooked the regulator, and the dim generator light is completely gone.

here are the #'s for voltage though....

startup (runs rough) 12.0-12.2 600 rpms for a small amount of time, then went to 13.5-13.6 volts and ran like that for minutes... slowly going to 13.9, 14.0, then at full temp, the car runs great, and is at 14.5 volts, 860 rpms. turn on the lights and the volts go down .2-.3 volts, turn on the ac and another .2-.3 or more drop, and 670rpms or so w/ ac on.

Is this right?

I have .2-.3 volts more at the alternator too. Should I add another wire from the battery straight to the alternator to reduce the wire resistance?
 
#7 ·
Your voltage numbers sound fine.

The car's main junction block is the 2 screw terminals on the horn relay, are you dropping any voltage there as compared to at the alternator?
If you are, you could run another wire from the alternator to the horn relay.