Indicator light


Old 02-09-05, 05:53 AM
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Indicator light

1990 Pontiac Grand Prix 3.1L.
While driving, the "Check Gauges" Light will flicker and come on. Sometimes it stays on for a while, sometimes it will flicker and go off for a mile or so. I checked the gauges and the only one I see any problem with is the voltmeter. It runs around 16 volts while driving, and drops down to 13 volts at an idle. I noticed when I'm coming to a stop the needle will drop down to 12.5 volts when the brakes are applied. I also noticed the turnsignal works normal until you slow down, then it also starts flashing slower. Any idea on this.
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Old 02-09-05, 02:02 PM
Join Date: Apr 2002
Location: Pittsburgh,Pa
Posts: 2,417
Don't trust the voltmeter in the dash it may be the problem.Check the voltage across the battery terminals with Dvom it should be between 13.5 and 14.7 if everything is ok.If it reads hi there 16v as you stated it reads inside you need to test the battery to see if the alternator is trying to charge a bad battery.Many auto parts will test both for you (no charge) if you drive your car over or carry the parts in.Call around before driving all over the place.
Old 02-10-05, 10:19 AM
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Posts: n/a
Heres what I did.
I had the garage hook up to the battery with the car idling. Voltage was 14.2. I increased the rpm and the voltage went to 14.7. I turned the headlights on at idle speed and the voltage dropped to 13.9. I turned the high beams on and it dropped to 13.7. I applied the brakes while idling with the high beams on and the voltage dropped to 11.9. The alternator was very hot to touch. Could this be the alternator or the battery causing the alternator to work hard?
Old 02-10-05, 07:49 PM
Join Date: Nov 2001
Location: North Texas
Posts: 2,345

Sounds like battery is shot Alt is charging a dead horse keep it up and soon you will have to replace a alt.
Old 02-10-05, 09:27 PM
Join Date: Dec 2001
Location: nc
Posts: 616
I'm going with a bad alternator. You didn't mention any problems starting the engine.

Either way, you need to have a test done on the battery and alternator and if not fixed soon, you'll be replacing both.

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