Hi, this is for my friend's '89 RS which is currently stuck in my driveway. It has a 305 tbi. The car has been having problems for some time that I just thought was a bad alternator. The voltage guage always read very low, like around 10-11 volts,and since this is what my car was doing when the alt started to go I just figured that was the problem. The alt has been replaced with a brand new one because it actually did die, but the problem was still there and now it is not charging at all. I know it's not the alt that's causing this because we also tried an extra one that I had and it made no difference. Does anyone have any ideas about what would cause this? I checked the main (big) wire going to the battery and it is not shorting but I'm not sure what to look for otherwise.

 

There should be two orange wires coming off the alternator going to the power terminal of the battery probably connected to the starter wire. There is also a fusible link in the line somewhere. If the car is running there should be 12 volts coming from this wire. I believe if the fusible link is broken it could prevent charging from the battery. Not too sure how to test this try a voltmeter at the alternator connection( the two orange wires) (with the car off) if you get no charge the fusible link is bad. The alternator supplies voltage when the car is running so if you check while running it wont be able to tell if it is bad. I hope this helps if you need any help let me know hope this helps
JMFNX@AOL.COM
1989GTA

 

Sorry if I misread the post if it is not starting and has been charged it could be the fusible link at the starter. These are the two orange or red wires comming from the starter connected to the thick starter wire. The way to test this is see if it has power supplied past these fusible links. If these are bad the whole car will not have power this happened to me last week.
JMFNX@AOL.COM
1989GTA

 

First, check the large wire coming from the rear of the alt. Disconnect it from the rear of the alt. It should read 12 volts. Next you should check the state of charge of the battery. 87 and up use the CS series alternators-they will NOT charge if the battery is not at least at 75% of terminal voltage. The two wire plug should have 12 volts on both pins with the key on and engine NOT running. I cannot emphasize the importance of a fully charged battery when diagnosing a charging problem.