Gen Light/Diode Trio?
Thread Starter
Pro
Joined: Dec 2004
Posts: 534
Likes: 2
From: Connecticut
Gen Light/Diode Trio?
My Gen light just came on real bright. I pulled the connector on the alternator and the light went off, so I assume I need a new diode trio.
My question is what would cause the trio to fail? I just replaced it the trio about 500 miles ago. Also, the gen light is real bright this time and last time it was dim when it came on.
Thank you
My question is what would cause the trio to fail? I just replaced it the trio about 500 miles ago. Also, the gen light is real bright this time and last time it was dim when it came on.
Thank you
Team Owner
Joined: Aug 2006
Posts: 24,125
Likes: 15
From: Columbia Missouri
What kind of electrical strain does your alternator have? Do you have large draw components like stereo or electric fans?
Generally the diodes fail when too much of a draw is put on the alternator and it's running at high output all the time.
Generally the diodes fail when too much of a draw is put on the alternator and it's running at high output all the time.
Race Director
Joined: Sep 1999
Posts: 11,360
Likes: 382
From: Plano TX
How about a bad battery? I once had one where a cell shorted. The voltage was 10V instead of 12V. The car still started & ran but the alternator was pegged.
There's also a voltage regulator inside the alternator that can be bad.
There's also a voltage regulator inside the alternator that can be bad.
Thread Starter
Pro
Joined: Dec 2004
Posts: 534
Likes: 2
From: Connecticut
Could the battery be bad even though the gen light went off when I disconnected the connector from the alternator?
Team Owner
Joined: Aug 2006
Posts: 24,125
Likes: 15
From: Columbia Missouri
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Thread Starter
Pro
Joined: Dec 2004
Posts: 534
Likes: 2
From: Connecticut
Does this tell me anything?
Battery with car off testing with probes on the + and - was 12.13V
Battery with car running was 11.99V
Alternator plug with car on but not started... Red wire 12.5V and white 11.6V.
Battery with car off testing with probes on the + and - was 12.13V
Battery with car running was 11.99V
Alternator plug with car on but not started... Red wire 12.5V and white 11.6V.
Last edited by DO2G; Apr 8, 2007 at 01:23 PM.
Race Director
Joined: Sep 1999
Posts: 11,360
Likes: 382
From: Plano TX
Battery looks good (although somewhat discharged).
I guess your best bet will be to replace the diodes again, but see if you can get better quality. Does AC-Delco still sell just the diodes?
I guess your best bet will be to replace the diodes again, but see if you can get better quality. Does AC-Delco still sell just the diodes?
Advanced
Joined: Nov 2006
Posts: 89
Likes: 0
From: angola new york
nothing will kill a doide trio like a bad regulator.i suspect that that's what went wrong first and it took the diode trio with it. i never change one without the other also. and don't EVER i repeat, EVER unplug an alternator while the engine is running. that will deffinetly toast the regulator.
Last edited by general69; Apr 8, 2007 at 02:15 PM.
