|I have a 1993 L-8000 ford truck with the 7.8 diesel. About a month ago I went out to find it dead. Charged the batteries and it runs fine. When I look at the volt meter on the dash, I can see that the alternator is not charging. When I turn lights on I can see the voltage dropping on the meter. The more stuff I turn on the more it drops. I used my multimeter to test the batteries when the truck is off and all 3 batteries are about 12.7V. When the truck is running the volts on the batteries show about 12.3. That made me think the alternator was not charging properly. |
I got a new alternator, put it in. No change. The alternator I put in is a Delco Remy 22SI (same one that came out). Thinking maybe I got a bad alternator I took it back, put another one in and I still don't get any charge.
I read up on voltage regulators and I'm pretty sure mine doesn't have an external one. I believe mine is internal to the alternator. I could be wrong about this but the only place I see anything that could possibly be a voltage regulator is behind the air intake and when I cross reference the part number it says its a starter exciter solenoid.
I tried to follow a you tube video and "bench test" my alternators. I took a screw gun with a socket and ran them up while holding the multimeter on the cable that says battery and the negative. Those are the only two places the alternator connects to my truck with wires. I assumed I would get like 13.5 - 15.0 volts when I did this test. When I test them one alternator reads like 0.6V, one reads like 0.3 and one reads like 0.10. I assumed if the alternators were all good they would all read the same voltage. I don't know anything about bench testing these so I might not even be doing it right.
Is it possible I have 3 bad alternators? What else should I be looking for. All my wires are cased in rubber so I can't trace them very well. There are 2 wires that come out of the rubber right where it hooks into the alternator and I'm pretty sure those are correct because I have owned and run this truck for over a year with no issues until a month ago.
Really appreciate any advice anyone can offer on this problem. Thank you in advance.
Edited by rollinghorseranch 3/19/2023 11:32