Ok, this is a write up on how to do an external voltage regulator conversion on any and all Chryslers with the reg in the ECM and an unregulated alternator. Till now, if you have charging issues with these trucks you had to replace a $3-500 computer. I did this conversion for $43.28 after sales tax. This can also apply to other trucks if you'd like add a second alt, or the wiring is fried.

Here is a list of parts that will be needed with prices as of 8/3/2011.
Regulator part #MPI 2VR1 price $13.99
Regulator plug/pigtail part #BWD PT173 price $8.49
1 coil of 14ga wire $5.99
1 pack of butt connectors $5.99
1 pack of ring terminals $5.99


These are the prices and part #s at my local O'Reilly.
Also a couple of self tapping screws.


The first thing you need to do is remove the little plastic box on the back of the alt.



Tape it up so it won't short out and tuck it out of the way (you will not be using it).


Find a good solid place on the firewall or inner fender to mount the regulator. If you don't have a place with a good ground, you can run a ground wire off one of the mounting screws. I mounted mine behind the battery on the metal fenderwell so no need for a ground wire on mine.
Mount the reg using the self tapping screws making sure you have enough room for the plug to stick out from it.


Cut two lengths of wire long enough to reach from the alt to the regulator. Crimp a ring connector large enough to fit the bolts the plastic block (removed in step 1) was attached to on to each one. Put them on and tighten the nuts down.


Once the wires are connected to the alt, cut a wire long enough to reach from the reg to an ignition pos of your choice. Take one of the wires from the alt (doesn't matter which) and the wire from the ignition pos and crimp them into one end of a butt connector.


Take the doubled wire (batt and alt) with the butt conn already attached and connect it to the TOP terminal on the pigtail. Take the other wire from the alt and attach it to the other terminal of the pigtail using a butt connector. Plug the pigtail into the reg, route the wires out of the way and reinstall the battery.



Start your truck and make sure it's charging properly. If so then you're done!

Take the money you saved from not buying a new comp, buy a six-pack and another upgrade for your truck!!


DOWNSIDE TO THIS MOD__ The only downside is that after doing this, your check engine light will stay on since it has no signal from the alt. There is no way I know of to prevent this, but someone here might have an idea. If that is an issue to you, then this conversion may not be for you!

 

Good Write up. What code are you getting?

 

I would think there should be a way to get 12v back to pcm to indicate that alternator is working to clear and code that is triggered.

 

The codes are for the charging system since it's not getting field current signal from the alt anymore. The problem with wiring it this way is when you remove that block from the alt, it cuts off the signal to the comp. If you leave those hooked up, the comp will still try to regulate it and you'll still have the same problem as before.

 

It's not just feeding 12v to the comp. Chrysler WAY over engineered the original system (2 field currents, air temp and battery temp sensors). If you find a way, I'd be grateful. As far as I know it isn't possible. If you give voltage back to the ecm, the comp will still be trying to regulate the charge and you'll still have the same problems.

 

what ZJ did you do this on?

 

I believe it was on his 1987 Dodge Ram LE.

 

it wasn't on his truck. it was on a jeep. truck already had that voltage regulator system stock from the factory in 87. plus the battery in that picture is on the opposite side of of my trucks

 

It was on my mother's 93 Grand Cherokee. The reg in the comp was bad and it was giving the batt 18+ volts!

 

Just picked up a 1998 V10 yesterday. A it turns out it has a charging problem. New battery, new alternator, and tried writing in the voltage regulator fix above. Sill not charging! Double and triple checked everything.

Any other ideas?