Good Morning Guys, 

Tried the search function but couldn't find what i was looking for. I have a 93 W250 Cummins I am bringing back from the dead. The voltmeter is swinging from 12v to 18 v and i want to install an external voltage regulator to remedy this situation. Yes, i know the OEM regulator is contained within the PCM. I will be doing a PCM delete eventually and the truck will be fully mechanically controlled. So, back to the situation at hand. I have the older style square voltage regulator and not the one with the triangle looking plug. The one I want to use has screw connection points for eye lug or fork lug connections. The original OEM voltage regulator controlls voltage by allowing a ground to make up to energize the field on the alternator. So, if I connect one side of my field to ground at the alternator and the field connection from the voltage regulator to the other side to the field connection on the alternator, the regulator should control the field and therefore the voltage right? I will use a relay to power a voltage sensing line straight off the positive post of the battery so the regulator will see the actual battery voltage instead of the voltage drop from a switched 12v source, hence the use of the relay. What are your thoughts on this install??

Edited July 16, 20195 yr by JAG1
Correct spelling

Actually yo can get that PCM repaired. @Auto Computer Specialist can do it  for a fair price. 

 

Without the PCM you will not have any speedometer. I'm pretty sure ABS and PCM work together to get speed signal to the dash. Then your transmission will need the PCM to get 4th gear lock up.

 

I do not suggest external regulators. They were discontinued for a reason which is the engine bay heat has to be just right to prevent over charging or under charging. If the regulator is too cold the charge voltage is too high. Then if the regulator is too warm then charge voltage is too low. Really common problem batteries don't last very long typically.

Edited July 16, 20195 yr by JAG1

I understand that the PCM can be repaired, but they arw not making PCM's anymore. So any repair I have done on this PCM will still be on a 25 yr old PCM and getting older every day. I had an 85 W250 with a 360 gasser and it was all mechanical and bulletproof. I want to go in that direction with this 93 resurrection. I was wanting to know if I wired in the external voltage regulator as explained in my previous post would it work? 

Edited July 16, 20195 yr by Butterbean150

Ok... Here you go...