Ok, replaced everything multiple times including the PCM, still showing 16.5+ volts at the battery when running.

I suspect that a field wire id grounding somewhere, but I can't seem to find it.

So, ready to do the external regulator. Just bought a nice 75 amp relay, but unclear about the wiring.

Can someone post a drawing of how to wire up an external regulator using a relay?

 

Is this what you are looking for?

http://www.thedieselgarage.com/forum...ad.php?t=58251

 

I was looking for a way to "fool" the PCM so it would not throw a check engine light.

 

Have you tried cutting the dark green field wire at the PCM to see if it still overcharges? That would for sure show you have a grounding issue in the wiring. If so, then I would just run a new wire to cavity 20.

You want to verify cavity 20 is the field driver on the diesels the same as it is on the gassers.

It is possible you have multiple bad PCMs

I am pretty sure no one has figured out how to do the external regulator and keep the check engine light off.

 

I've done the external regulator cause my PCM is problems and it is a lot cheaper to just bypass the things that don't work. The external regulator has no gave me any problems my check engine light is on but it don't bother me any. I charge an about 15.3 volts and hasn't hurt anything is kinda nice cause the lights a bit brighter.

 

What is the voltage at cavity 57? Say compared to right off the battery.

 

Well, I did the external regulator hack again. Voltage is 15.1 but that is better than 16.5. Still a little concerned about battery life... Optima Yellow top is a few months old.
When i get time i will disconnect the green wire and see what happens. I would rather keep things tidy running through the PCM if possible.

 

I will check the voltage ay cavity 57 this weekend.

 

ive got a part on the shop counter that satisfys the pcm from coding when switching to external regulation, I did this a while back, ill dig it up.....

 

Thanks Sooty!

 

also, I remember a similar van, had connection issues within the harness, the blue ignition feed "sense wire" needed to be at the battery, reading the volt output coming from the alternator, I wired in a ignition switched relay to the blue from the battery, and volts dropped. this will still be operating on pcm.

 

I picked up a 75 amp relay (overkill) just in case.

 

ive done conversions with biltit's post successfully, but the pcm controlled alternator will lose whats feeding from the small blue ignition wire, restoring battery feed volts fixed it, give that a shot first, im only talking 1 volt, 14.5 is what you want, at your precious (coniptima) battery.

 

I dont understand. So make sure the blue wire has full battery voltage with a relay ?

 

blues from asd relay to alt, check voltage running at blue