GM Alternator Problems

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  #1  
Old 12-25-11, 02:23 PM
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GM Alternator Problems

Thought for sure it was the diode trio, not sure now. I'm getting zero in one direction and 225 (looking at the DC scale) in the other on all three legs. Seems okay?





Left prong on plug is (1) right hand side is (2)


A, B and C to prong 1 is 50.

A and B to prong 2 is 120.

C to prong 2 buries the needle to the right.


Anything else I can test on this, I'm lost now?

Thanks
 
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  #2  
Old 12-25-11, 02:30 PM
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Guess I should explain what was happening. Driving at night the lights would start to dim, radio would be garbled and then zap it would go back to normal.

Exact thing happened on a Cutlass I had years ago, it was the diode trio yet this one seems to check out fine.....I think.

Battery was almost dead this morning, sure seems like the alternator.
 
  #3  
Old 12-25-11, 03:00 PM
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i think the diode is the part, that i can see 1 terminal of in the bottom right corner of the photo

the meter should read full continuity from the single long terminal to all 3 of the short terminals.
then switch the meter leads & you should have no continuity between the same

the finned part in the back of the housing that the 3 stator wires attach to with the diode is the bridge/rectifier

don't know if this answers your question or not

mike c
 
  #4  
Old 12-26-11, 06:20 AM
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Use the Ohms scale.. not the DC scale.
 
  #5  
Old 12-26-11, 08:34 AM
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Use the Ohms scale.. not the DC scale.
Well....I was using the DC scale because it is the easiest one to see, eyes aren't what they used to be. From what I can find is all you're doing is seeing if the values are close between the diodes.

Tinkering with it last night I found one of the diodes in the rectifier bridge was bad. First two had steady values, third one was hit or miss, usually miss.

Might be a problem finding parts locally for a 83 alternator, hope not.

Thanks
 
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