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Electrical

Tiny
GEORGEYOUNG
  • MEMBER
  • 1994 CHEVROLET LUMINA
  • 6 CYL
  • FWD
  • MANUAL
  • 178,000 MILES
I have a 94 Lumina APV with 3.8 that I am having an electrical issue with. All the electrical system pulses at times mostly when the vehicle is cold. It will stop at times and run for hours but then start again for no apparent reason.I think it may be a surge in voltage causing the problem.I found that the small wire going to the alternator is pulsing when this happens and would like to know where that wire originates from. Thanks
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Monday, January 10th, 2011 AT 8:25 PM

8 Replies

Tiny
JDL
  • MECHANIC
  • 16,098 POSTS
I'm not sure which little wire your talking about? Note the diagram.
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Monday, January 10th, 2011 AT 8:52 PM
Tiny
GEORGEYOUNG
  • MEMBER
  • 12 POSTS
I can't tell based on the diagram but there is the hot wire from the battery that bolts on to the alternator and then there is a plug with two wires on it. The larger gauge of the two wires is hot. The smaller gauge of the two wires is sending a voltage that becomes inconsistant (or pulsing) at times and causes all the electrical system to pulse along with it.I'd like to know if that current originates at the ecm or a circuit breaker. Thanks for your help.
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Monday, January 10th, 2011 AT 9:29 PM
Tiny
JDL
  • MECHANIC
  • 16,098 POSTS
You click on the diagram to make it larger, note the wire color. Also, look at the letters on the wiring connector, l--s--f? I'll double check wiring.
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Monday, January 10th, 2011 AT 9:46 PM
Tiny
JDL
  • MECHANIC
  • 16,098 POSTS
To add, this is info for your charging system. Engine running, I don't want to see less than 13 volts, as much over as I can get. Are there driveability issues?
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Monday, January 10th, 2011 AT 10:06 PM
Tiny
GEORGEYOUNG
  • MEMBER
  • 12 POSTS
I'm going to guess that that it is the wire marked "l", I have already replaced the alternator and battery with brand new ones, I feel it's a faulty relay or module but don't know how to locate it.I am not a mechanic by any means. Thanks again.
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Monday, January 10th, 2011 AT 11:07 PM
Tiny
JDL
  • MECHANIC
  • 16,098 POSTS
I didn't see an I in the diagram, did you mean L? Forget the pulsing wire for a minute, what is the actual problem? Is the charging system not working? The L terminal goes to the pcm.
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Tuesday, January 11th, 2011 AT 3:38 PM
Tiny
GEORGEYOUNG
  • MEMBER
  • 12 POSTS
The actual problem is the pulsing. It causes everything in the van to pulsate. Headlights, interior lights and the engine loses power with every pulse.I now believe it's the pcm.I'm going to change it out. Thanks for your help.
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Tuesday, January 11th, 2011 AT 6:49 PM
Tiny
JDL
  • MECHANIC
  • 16,098 POSTS
Good luck
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Tuesday, January 11th, 2011 AT 8:16 PM

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