Alternator failure: SOLVED

[LMP]

(93 TS) Was going to the airport yesterday and suddenly, the voltage started going down and up for a few seconds, then fell low, battery only....and came back as I reached the airport. WHen leaving, started charging for half a mile then fell down to battery voltage. As battery is old and barely keeps a starting charge after a few days....voltage went down to the bottom within 5 minutes and engine started to hesitate while all needles went haywire....was able to reach a safe parking place and called wife to come with "emergency vehicle"....(that is another story...saved for another day).
Used rescue car to charge battery for a few minutes, then was able to start and reach home, barely, just 3 miles away. Engine stopped in front of my garage,had to use battery charger to enable car into the garage. (Hey..still cold here..and my garage has a full home heating system just for itself AHHHH....heat).
WEnt investigating this morning....and to make a short story even shorter, found the exciter plug to the alternator had pulled off.... It is in such a weird location that I had to pull the alternator from its place to enable reinserting the plug...and once reinstalled, all is back to normal.

OK, that is simple and silly, but I want it to be remembered as a possibility .
Reason: I had in fact removed the alternator and disconnected the plug several months ago to make a test on another car....and the lock tab on the connector had lost its natural elasticity (well, after all, this plastic connector has sustained engine and alternator heat for 18 years ) and after reinstallation, had not locked-in in a very positive manner...I remember that...so after several months, it finally pulled off by itself...

SO...if at some time you have pulled the exciter connector off from the alternator, keep in mind it might get loose by itself in the future....

[Jrs3800]

Good Find.....

Another one to keep an eye out for is the Charging Circuit that leads to the starter + pole( main pole/Battery Cable + ).... I have had and seen these wires break right at the Fusible Link...

For mine when this happened I could not figure out why I thought the alternator failed.. Installed a new one with the same result.. Did some study of the circuit and checked at the starter pole... I found my problem... A bad + wire from the alternator... I have a 125 Amp Alt on my Bonneville( factory ) and the positive wire was roughly 3 times the size... I could not figure out why GM would use such a tiny wire/wires for a 140 Amp unit...

Being that the set up I have is computer controlled, PCM tells the alt what to do, I installed a large Battery Cable from the back of the Alt to the battery, same way the Bonnevilles are set up... I have since had no charging issues at all even when all of the accessories are turned on...

Major Shame on GM for setting these charging systems up with speaker wire....lol

[rkvons]

The story you describe here is exactly what happened to me and my 1998 TS. My wife and I were on my way over to my parents for thanksgiving one year and it hit me. My father had a spare battery in his garage, but that only got me home. In my case, it turned out that the little tab that was supposed to latch in the connector had excess flashing on it and did not allow the connector to snap over it properly. I removed the excess flashing and it was good from that point on.