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Voltmeter Pegged All The Way On +


Diseazd

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Just rebuilt my L28 and put a new alternator. Hooked everything back up as before and now my voltmeter is pegged all the way to the +. Also my left headlight is so dim as to barely see it. Furthermore the belt even though it was tightened properly was squealing like it was overworking. I put the old alternator back on....still had the problem. I believe the alternator was hot also, but that could be engine temp. What's the cause?

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:ermm:

Do you mean VOLTMETER or AMMETER?

I really need to know which it is, VOLTS or AMPS.

A Voltmeter is usually marked from say 9V to 15V no polarity indication whereas an Ammeter is centre zero with markings of

-45, 0 and +45 for example.

It sounds like your Alternator is running UNREGULATED:finger::finger::finger:

This will cause the battery to EXPLODE if left too long!

You need to check all the connections as a matter of urgency to rectify the problem.

The squealing may be a misaligned belt/pulley, or it may be due to the extreme current draw mentioned above.

The dim headlamp is probably due to a faulty ground for that lamp.

It may be that both filaments are operating in series instead of using the ground circuit.

post-13952-14150803649858_thumb.jpg

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Thanks for your reply Nissanman.......It is the ampmeter on the dash....It's reading all the way to the right at higher RPM and stays there till I go to idle. I installed a new alternator and then went back to the old alternator with the same result. I have a new voltage regulator here I could try........could that be the problem? All connections are as were before the rebuild.

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The fact that the alternator charge current climbs with engine RPM indicates that it is more likely a Regulator issue, or, a wiring problem between the Alt. and Reg.

Here is a diagram of the typical Alternator and Regulator wiring connections,

The B wire at bottom left is a GROUND wire.

post-13952-14150803650416_thumb.jpg

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I had this same problem a few times after I put a new internally regulated alternator on mine as well.

It would squeal VERY loudly, the ammeter would jump to + and I would panic. Upon inspection, I found the alternator itself to be very hot to the touch. I determined that the belt was not tightened correctly and must have been slipping. This created friction and caused the alternator to heat up. I'm not sure it the ammeter reading was a result of increased resistance due to heat, or if it was working when it wasn't supposed to be because of the slippage issue.

Either way, after a few tries, I got the alternator positioned correctly to provide just the right pressure on the belt and haven't had a problem since!

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Thanks again Nissanman.......I had an old voltage regulator that I plugged in and the problem seems to be solved. I've never had one go bad before....any thoughts on what would kill the voltage regulator? The headlight issue seems to be unrelated (as you guessed ). I appreciate your assistance as always. Good Luck! Guy Jonnyrock- You're right.....the extra draw probably worked the belt harder and heated up! Thanks Guy

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I've had that happen with my internally regulated alternators also. I used to open them up and replace the regulator unit but those are getting harder to find and it's much easier just to replace the whole thing. I've had regulators die on a few occasions over the years and never really figured out a cause other than age.

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The dim headlight could be your fuse. Even though it's not blown it could be making you headlight dim. I had this problem before and read about it on this site. I changed the fuse and it was nice and bright afterwards. Might be worth a try.

-Paul

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Paul.....Bingo you got it.....I took out the headlight fuses and put them back in. Everything works perfect.....must have been a little corrosion on the fuse. Thanks for everyone's help. Now everything is perfect!

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Paul.....Bingo you got it.....I took out the headlight fuses and put them back in. Everything works perfect.....must have been a little corrosion on the fuse. Thanks for everyone's help. Now everything is perfect!

Glad to be a help. Gotta love those quick and easy fixes :)

-Paul

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