81 chrysler lebaron/voltage regulator

furyfrank

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Have a 81 lebaron that keeps blowing voltage regulators, any idea what could be causing it ??
 

ruppster

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Okay, here's a few things to check with the multimeter.

1.) First make sure you have a good ground wire from the engine to the firewall.

2.) Then check the alternator housing for a ground stud. If it has one check the wire that's connected to it and make sure the other end of it is properly connected too.

3.) Check the bolts that hold down the voltage regulator for corrosion. Take a wire brush to the underside of the bolt heads and make sure to us a couple of star washers with the bolts.

4.) IIRC there should be 3 wires to the alternator (other then the ground wire). One is the output stud and the other 2 should be 1/4 inch spade connectors. These 2 spade connectors are for the field winding. One spade connection should be 12 volts and the other one is the output from the voltage regulator. Do an ohm check on the wire that goes from the voltage regulator to the spade connector on the alternator (do this with both ends of the wire disconnected). Should be a green wire on the end that connects to the alternator.

5.) With both spade connectors removed from the alternator check for continuity between the 2 field terminals on the back of the alternator and chassis ground. Should not be any continuity. If you find a connection here you have a shorted out winding in the alternator. Also check for continuity between the 2 terminals themselves (should be a few ohms). If you get no continuity then you have an open in the charge circuit within the alternator.

6.) Turn the ignition key on (but don't start the engine) and check for 12 volts on the other spade connector (i.e. not the one that goes to the voltage regulator).

7.) After all that put all the connections back (if it all checks out okay) and set the multimeter to DC voltage mode and check the voltage at the battery. Should be around 12 to 12.5 volts. With the multimeter still hooked up to the battery start the engine. Voltage should go up to at least 13.5 to 14 volts.

8.) While this isn't related to your problem one other test that can be done to the charging system at this point is to check the load capability of the alternator by monitoring the battery volts (with engine running still) as you turn on things like the AC/Heater, wipers, radio, and any other powered item you can. If the voltage starts dropping bring the engine rpm's up to 1500-2000 and see if the voltage comes back up. If not then one of the 3 output coils could be bad (or a bad diode).
 

furyfrank

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I finally got to check a few things out, first when the key is turned on the ammeter shows a discharge ( which I think is normal) after starting the ammeter pegs itself to charging full.
 

furyfrank

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OK I also have a 87 fifth ave with the same engine, and checked the wiring on it and it looks different, could this be?It seems like the 81 has more wires, will check it out today.
 

ruppster

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First thing you need to check is to make sure it isn't over-charging the battery. Perform step #7 from my previous post.
 

NoCar340

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A pegged ammeter would indicate that either the alternator itself is damaged, or one of the field wires is grounding. Even with a totally-dead battery, it shouldn't peg right out. My '81 Imperial had the big 100A Leece-Neville style alternator, and though all the wiring was OK it was internally shorted somewhere in the alternator. It burned out the digital dash, blew every bulb in the car, and made the battery look like a pillow. It was pushing out over 17V at idle.
 

furyfrank

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Tomorrow I think I am going to take the alternator to autozone and have it checked out.
 

furyfrank

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Today got in the car and started it the amp guage stayed in the middle where it should the only thing I did was move a couple of wires around in the engine compartment will check it out further.
 
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