jdehn

I have a 89 GT. I was driving home the other day I notice the gauges in my car started acting wierd. I got into the car later to pull it into the garage and it wouldnt start. I replaced the alternator with a remanufactured part from advance auto and the alt they gave me was bad. I exchanged that one today and had them test the new one before I left and it tested fine. I installed it on the car and the alt light is on in the car and the voltage gauge is only reading about 8 volts. I checked the voltage at the alternator and its only reading 5 volts and it doesnt change when I bring the rpms up on the engine. The battery was fully charged when I started and I changed the plug for the alternator.

Im lost now and not sure what else to check. Thanks in advance for any help.

Jason

DrmZero

make sure you have a solid ground... if its a lttle rusty or loose then it wouls cause poor output..

onesickstang01

yea ground is the only thing i can think of too. otherwise if you changed the plug then maybe you have a weak connection or something through that

jdehn

Where would the ground for the alternator be? Do I just follow the wires from the alt to find the ground? I thought this could be a problem so I added another ground wire from the engine to the chassis last night.

Jason

projectresto83

Check your main grounds on the frame and one the block. If those are good you might want to check and see if any of your fusable links in the wiring are blown. These are not regular fuses either. They are a smaller gauge wire added into the harness that burns up like a fuse would. They are easy to find, it says fusable link right on it usually.

jdehn

I checked the voltage right at the alternator and wasnt getting but 5 volts. Could the fusible links still be causing my problems? If so, how do I check to see if the fusible links are good?

Jason

jdehn

I was just out looking at the car and I believe it may have an underdrive pulley on the crank. If it does could this cause the low output voltage on the alternator. I have a stock crank pulley, should I install it and see if that will fix the problem.

What diameter should the stock pulley be?

Jason

projectresto83

YOu can check the link by probing the wire on each end of the link. Having an under drive crank shouldn't cause it to be that bad. Not sure of the exact measure but mine was about 8 inches. Reenstall it and see what you got.

jdehn

I drove the car up to advance auto to have the alternator checked on the car and the alternator is not energizing. Does anyone know which wire tells it to energize so I can check to see if there is a wiring problem. The small amount of voltage that was showing at the alternator is just what was coming back through the wires.

Thanks,
Jason

notchbackmatt87

just get a new alternator dude spare your self fixing a wire and two months later having the same problem do it the right way get yourself a nice new bigger amp alternator.