I was driving my 87 home when i looked at my dash and noticed the volts were around 11.0 as opposed to the normal 14. As i kept driving they got lower and lower so i pulled into a parking lot where it died. After a jump, the car would only run for a few mintutes then die. I know the battery is new so i suspected the alternator. I looked at the connections and saw the 3 wire plug and also the red battery cable, but there was an unconnected thin green wire with a white stripe that was disconnected. I looked around and didnt see where it came from. The tow guy said it was probably the excitatory wire. Can any one shed some light on this, thanks in advance.

Welcome to the site. I just went out and looked at my '87 and the only wires on it are the single heavy gage red and the three white wires in the harness plug. Perhaps the green wire you speak of is just an unused wire . Close by the alt. I have two green wires but they go to a sending unit in the head. It sure sounds like a classic case of a bad alt. I'll look in my factory manual and see about the green/white wire you have. Good luck with it. Cheers.

I just looked at mine too, my 85 only has a 2 wire plug and the battery wire, guess they changed them between 85 and 87. Blueshark is right, it does sound like a bad alternator, most auto parts storeswill test it for free.

Good luck, and welcome to the Corvette Forums

thanks for the quick response and the effort, ill bring the alternator to autozone tomm.

ORIGINAL: axesolo03

I know the battery is new so i suspected the alternator.

Welcome there!

How new the battery? Hours? Or days?

If it's just a few hours, it shouldn't cut off; it should run off of the battery until the battery is dead.8 hours or so, unless you got the fan on, lights on.

No telling how long it wasdischargingbefore he noticed it, you would have to take into account all of the electronics these carsuse just to run. Fuel pump, and the ignition coil would be a big drain on it. I would assume, the ECMwould have a minimum voltage thresholdto even function properly.

Also perhaps the connections on the alt and/or battery are corroded. Over time the battery would not get a full charge even if the alt. was fine. That just happened to me to a certain degree and the starter dragging added to the over draw on the system. Hope you get 'er fixed. this is the best time of year to be driving. Cheers.

ORIGINAL: rshiver

No telling how long it wasdischargingbefore he noticed it, you would have to take into account all of the electronics these carsuse just to run. Fuel pump, and the ignition coil would be a big drain on it. I would assume, the ECMwould have a minimum voltage thresholdto even function properly.


Yeah, could be.

Where is this guy? Saturday night; probably burnin' alternator $$$ for ethanol[sm=alcoholic.gif][sm=icon_guiness.gif]

Get your multimeter on the field output on the back of your alternator huh?

Sounds like the alternator and/or wiring is at fault, typically the green wire would be for the temp sensor in the head.

Replaced the alternator, everything seems to be ok! thanks again.

good deal! glad you got 'er fixed and thanks for letting us know. Cheers

ORIGINAL: axesolo03

Replaced the alternator, everything seems to be ok! thanks again.


Was the oldalternator puttin' out a charge?

ORIGINAL: cwb

ORIGINAL: axesolo03

Replaced the alternator, everything seems to be ok! thanks again.


Was the oldalternator puttin' out a charge?



i brought it to Autozone and it failed