I have an 83 Ram D150 Prospector with a 318. About a month ago I was driving and the truck slowly lost power and it killed on me. It turned out the Battery was not charging. I changed the alternator and it still will not charge the battery. I brought the alternator to be tested and they said it was fine so I changed the VR and still nothing. At that point I went ahead and followed a friends advice and checked all the fusable links and none looked corroded. When I put a volt meter on the alternator it wont put ot 13 volts. I had them switch it out even though the machine said it was fine but even the 2nd new one will not put out 13 volts.

 

with the truck off is there voltage at the larger lug on the alternator? did you make sure the vr was grounded good? could also check the 2 smaller wires at the alternator with the key in the on position. one of them should have 12v.

 

I just checked it. With the truck off there is voltage to the big lug. With the ignition on there is voltage to the lower wire and when I jump it and get it to start for a sec the voltage on the lower one goes away the the top one gets voltage. There is also a small white resistor of the firewall and the driver side. A friend told me that might be the problem. I checked it and it gets kinda hot while the truck is running. Could that cause it?

 

that resister on the firewall should not cause your truck to not charge. the only symptom of a bad resister is the truck will not run. did you try checking the resistance between the negative terminal and the casing of the VR?

 

We had the meter set to 200 ohms and when the truck is off it read .7 and when it was on it read 36

 

sounds like you might have found your problem. try running a ground wire to it and see if it makes a difference.

 

Tried running a ground wire but it still doesn't work. We are stumped.

 

did you accidently mix up the 2 small wires on the alternator? i know it should not make a difference but it might.

 

We thought the same thing and when we switched them and still nothing.

 

Are you sure power is getting to your battery? Your battery could be bad.

Make sure all your terminals are clean.


Possibly could be your 4way rectifier.