Ok at the battery with volt meter I have 12.4 volts.Start car and drops to 11.2.After a few minutes warm up then it jumps to 13.2 on the gauge and the volt meter,rpms will make it come up and down.Really erratic.Check 500 block and cleaned contacts with electrical cleaner.Test the fuse link going to battery and junction still reads the same.Now on the batt terminal out of the alternator it reads 5.8 volts.I used my alt tester on the battery it shows low output from alt all the time regardless if it reads 11.2 or 13.2 on the volt meter.I suspect alt is bad.The car has 109k and not sure if it has been replaced before.Thia is an 86 se 2.8.
The Bat wire? The big one? If that has 5.8 volts on it then you have a bad connection some place or a bad ground on the alternator. That terminal is connected right to the battery, so the readings on each end should be very close to the same. Larry
I am not sure how the terminal b on back of alt reads that low but at the battery I get 11 to 13 volts.I will try that again and see what I get.It really doesn't make since.If I had 14 v at the b terminal and only 11v at the battery I would say the cable is bad.
Alright pulled the alt and went to autozone.Tested it and it completely failed on three test.So they had one in stock ,installed. now the gauge reads correctly,no battery light,and at the battery I am getting 14.55 volts.YEAH!!!!!