So I leave yesterday morning and notice the light come on and the needle pegged to the top. If i started it up again it was normal but as soon as I start driving and revving up it did it again. I also noticed my windows and interior lights wouldn't work. Well now I go to leave and it's completely dead. It's a 99 f350.

 

what light comes on.
sound like the alternator voltage regulator is bad over powering the truck.

 

yea, rebuild or replace that alternator asap before you burn something up

 

X3 on the alternator. Mine was doing a simmilar issue a couple of months ago. The battery light was on but i didn't notice a change in the guage. Went to O'Reilly and they tested the alternator. It would work for a sec and then drop to 11 volts. Reman alternator and problems fixed.

 

X4 on the alternator, had the same problem happen on two Autozone alternators. The voltage would spike to 18 sometimes without warning, replaced the alternator, problem solved.

 

X5. My truck did the same thing a couple of years ago. Look into getting it rebuilt if you have a good shop. Will get a better product then a parts store one and cheaper.

 

Thanks guys

 

A voltage drop is safe, a voltage spike is dangerous

 

Ok so we put it on the charge for 4 hours on each battery, unhooked it then left it and when I got home at night I tried starting it and it was dead. Something is drawing the power. What could it be?

 

I went through issues over the summer with the batteries getting repeatedly drained. It got so bad that I disconnected the battery cables when not driving the truck until I could figure out the problem.

The problem with ended up being the windshield leaking water onto the GEM module on the driver's side under the dash. The GEM controls the door locks, the radio, and other general electrical functions. Symptoms I had were that the radio would stay on after turning off the ignition and opening the door. The remote door locks would stop working intermittently.

I removed the GEM module and cleaned it with rubbing alcohol. The windshield leak has been fixed and I no longer have the problem.

 

alternators have been known to draw your batteries down when diode goes bad inside