I can't see what the ignition switch would have to do with the alternator.

If the alternator is working correctly and it is still overcharging, then the field is being energized when it shouldn't be. Since the computer controls when the field is being energized and you changed the computer I would examine the wiring from the computer to the field terminal on the alternator. I don't have a diagram for the pin layout on the 93 but for 90 & 91 pin 20 on the computer feeds the field. I would also check what voltage the computer is receiving as that is the reference the computer uses to know when to turn the field on and off. If the voltage feed to the computer is low, say due to corrosion, then it would keep the field energized and cause an overcharge condition.

 

thanks seal, i will look into the voltage feed to the computer,when i get a chance. i do have all the wiring diagrams on disc. thank you

 

I checked out that site and according to them if you use a HO alternator you will need this kit or it could ruin your computer. Is that the case? I was comtemplating the HO alt since I plan on a lot of acc's like extra lights, alarm, siren, stereo, ac and possibly a winch. I have the Bosch 90 amp right now.
Any thoughts??

 

I have run most of those accessories, including the winch but not the siren, in my truck for years with a 90 amp alternator with no trouble. It is my understanding that if you are going higher than a 120 amp the computer regulator won't handle it and even the stock external regulator is not recommended. I have been told the field current draw is too high.

 

As far the lights go, I have 4 - 100 watt floods and 2 - 55 watt drive lights that may be on at the same time. Is there a way to gauge what a 90 amp alt can handle at once? The siren is cool and extremely loud. It came off my old 72 New Yorker. Stumbled across it by accident by flipping a toggle switch which armed the alarm. I want to use it for an alarm again, but think it would be fun to be able to scare the hell outta some folks. It sounds like an air raid siren - it just gets louder and louder.

 

amps times volts equals watts. 90x12=1080watts

 

Looks like it's more than enough to handle it with some left over. Thanks SEAL

 

well so far today i have also pulled apart the wiring harness from the computer to the alt. i can find no bad wires visually,also checked the main field term from the com. to the alt. wires all good.
i guess i will need to go further yet. when i get more time.
also i still am getting 14.9 volts to 15.3 volts output @ alt. thank you

 

Did you check the voltage being fed to the computer at the computer?

 

i did not check that yet. i cant leave it dissabled at all cause i need to use it for work.
had the harness out from alt to comp. checked wires with ohm meter,all are good. retaped all wires put in new wire loom,just so i know the wires are all good and that is not the problem.
i'll get to do more this next weekend. thank you