Electrical Low voltage

SMOKEDYA

Dirt-Old 20+Year Member
Jul 13, 2003
3,637
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79
Tucson AZ
Out of the blue my 98 GT battery light came on. I checked the voltage at the alternator and was getting like 12.xx, checked the voltage at the battery and was within +/- .x Checked the alternator and battery off my 97 the same as i did on my 98 and got 13.5 at the alternator and 13.xx at the battery. Figured my 98 has a bad alternator... So i took the alternator off my 97 and got the same reading of 12.xx and same reading at the battery. So i left the 97 alternator on my 98 and put the 97 battery in the 98 in place of the 98 battery, same results. Any ideas would be helpful while i search......
 
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Small update. I installed a new engine harness since mine was shot. Jumped the car with my wifes truck. Battery gauge was in the middle but the battery light was still on? Unhook the jumper cables from her truck and the car dies! Hook them back up, and same thing. Battery gauge reads normal but battery light was on. LEFT the jumper cables HOOKED up to the truck and my car.With my volt meter I Read 13.8 at my alternator and 13.8 at my battery. Unhooked the jumper cables and check the alternator. Reads 9.xx and drops like a rock until my car dies..... people are suggesting it could be the cluster? Any input on this yet from anyone... online search is doing no good for me....
 
Well yet another update.... Checked the fuses and found one fuse blown in fuse box,not sure what fuse,assume it was the alternator fuse? But it now holds charge at the alt of 14.2 and battery 14.xx no battery light and the gauge reads fine like always..... fingers crossed it was just a fuse... Now to determine what caused the fuse to blow to begin with...
 
It would help to know which fuse is blowing. There is an fuse that when blown will cause the battery light to be on all the time.

1999-2004 MY fuse panel schedule:

Howto perform charging system voltage drop test