1996 gmc 6.5 turbo diesel. my alt guage is dropping, i have 2 new batteries just put a new alternator on today and it stayed at 14 for about 30 min then dropped again. i have had it put on computer and it is not putting out the volt it is supposed to. they said alt again. is it possible or is it something else? please help its my only transportation. thanks

 

yes it possible that you got bad alternator

 

even if it is doing the same thing as the one i replaced? when they check the alt it is testing good. batteries are good so it has me confused

 

Take the Red wire off the back of alt and put Volt meter to stud and see what it putting out That wire from the back of Alt has a fuseable link in it

 

took wire off and put meter to it, my meter read 2.2.

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someone also told me possible computer problem, is this possible?

 

Your meter read 2.2 was that with motor running or off should be some where between 13 and 14.5 volts with motor running

 

took it to a dr. appt, took a corner to sharp and hit a good bump and it went right up to where it is supposed to be and has been good since. all wires are tight at alt and batteries. is it loose connection somewhere else and where? ground wires from batteries are tight also. i think my meter is bad, i put it on the battery and it read super low to, i will try a different meter tomorrow when neighbor is home

 

of corse it read 2.2 volts. your ''alternator'' has to have voltage to make voltage, c'mon guy's we're not in the 50s anymore. its not a generator.

 

I would check the small plug that go's in the back of the Alt. that is were your "Field wire" would be, that is the wire that sends the signal to the alt that the batt. needs power. If it has an intermittent connection or short it would cause the symptoms you describe. On my 96 there is another plug that connects those wires from the back of the alt to the engine wiring harness, check to see if it's properly plugged in. You might want to trace those wires as far back as you can and look for worn insulation.

 

I've had this same problem on my 84 6.2. I've replaced the batteries, gone through 3 alternators, made my own junction block on the inside of the fender and rewired all the electrical in my engine compartment, including down to the starter, fusable links, etc. All I can say is that perhaps it is the voltage gauge in the gauge cluster on the dash?