A friends car recently started going nutty with a bunch of lights and sensors coming on at once. It also gave him some trouble starting. I said for sure this sounds like a bad alternator, pull the alt and battery and get them tested at Autozone.

(Not long ago, I was working on the car and a wrench shorted from the alternator positive terminal to the UIM for a moment. The car started and operated fine but obviously this could be related)

So the Autozone folks say both the battery and alt are good.

That puts us back near square one.

Possibility 1: Connections to the alternator are not good.
Possibility 2: The autozone test might have missed something
Possibility 3: A problem not related to the charging system.

Any suggestions would be appreciated. We're going to reinstall the alternator and do a line voltage test with the car running tomorrow.

Dave

 

Sounds like you know the symtoms. . .I would guess it is "possibility 2." I've only seen 3 of these with these symptoms (including my own) and it was alternator every time.
--Jeff

 

if the dash warning lights all come on, the air pump clicks on and off and the alternator gets hot, its 99% the alternator.

 

Make sure that the two large plugs right in front of the shock tower on the driver side are seated and the clips engaged. They are the ones coming from the engine power harness. I have ran into a simular issue once and the plugs were not seated all the way.

Hope this helps,
Dan

 

Not sure how related it is, but I had an issue recently with my son's old Toyota. Idiot light came on but both the battery and the alternator tested fine...initially. A couple of days later it wouldn't start, dead battery which wouldn't hold a charge. Long story, but I ended up tracing it to a bad regulator within the alternator which had essentially fried the battery. I guess the point is, (as Jeff and Bill already suggested) it can test fine but still be bad under SOME circumstances.