hey everyone, I've got a 1987 Trans Am 5.0L with a digital dash. A few days ago the battery voltage dropped to around 12V and will not rise, if the car is idleing all the power options work but the dash will stay dim. When driving down the road things will randomly start to turn off. The sterio cuts in and out the turn signals/brake lights will switch on and off and the battery gauge will read no charge and suddenly jump back to around 12V

I've tested the alternator, belt, wiring and ignition switch all of which seem to be in decent condition. I even changed out the alternator and the ignition switch incase of a bad reading yet I still can't get the battery to charge off the alternator and all the wiring seems to be carrying the correct current. When I leave the car for 12+ hours and make sure everything is shut off the battery will be completely dead when I try to fire her up. I'm clueless as to what to check next, any suggestions??

 

check all your grounds...could be something like that

 

Check the FAN/FP fuse in the underdash fuse panel. The alternator recieves its activation signal from that fuse. If the fuse is good, check for power at the main charge wire at the alt post with key off. Then check for power at all wires of the rear alt connector with the key on. All these tests should show power.

 

Hey guys, I'm having the exact same problem as "tripleblue" I have the same car, 87 Trans Am with a 5.0 L motor, only difference is mine don't have the digital dash. That fuse you mention "ASE doc", on my car there is no fuse for that spot. There isn't even a fuse socket. Like when I try to put a 20 amp fuse in that spot, there is nothing to hold it in place, the fuse hole is empty. What do you guys think??

 

these third gen always have chargeing issues just you have to check all your main wire alt bat grounds all and any thing that has to do with the chargeing system ive had the same problem many times the only thing that worked for me was to get a alt from gm in detriot last one on the self two years ago

 

Do you think a rebuilt alt would cause this?

 

For the Record, my Alternator is a rebuilt one, it has the sticker. I dont know if would be the cause or not, but i know i have one.

 

Again for the record, I figured out the culprit. My rear hatch pull down motor was out of alignment, forcing it's cycle to not stop properly and "click" in the closed position, 6 hours later, I'd have a dead battery. So after re-aligning my hatch and the pull down motor, all is well, only complaint now is the motor itself is real slow, probably due to it trying to run constantly.

 

Thats interesting....I may have to check mine out Thanks

 

Did you ever check this out?

 

No not yet since I just bought a 67 Firebird and I am starting a resto on that