External Voltage Regulator Install With Pics - Dodge Cummins Diesel Forum
94-98 Electrical Tech articles dealing with electrical, wiring, gauges, HVAC, etc

LinkBack Thread Tools Display Modes
post #1 of 1 (permalink) Old 04-06-2010, 10:49 AM Thread Starter
Cummins Fan
Shocker444's Avatar
Join Date: Mar 2009
Location: Northwest Illinois
Posts: 77
Thanks: 3
Thanked 20 Times in 3 Posts
iTrader Score: 0 reviews
External Voltage Regulator Install With Pics

It's quite common for the voltage regulator section of the PCM (computer) to fail while the rest of the PCM is fine.
Rather than replace the $600 PCM just replace with a $20 regulator.

I am going to post the pics and parts I used for my external voltage regulator install on my '97 due to some confusion that I encountered when I was doing my own install. Hopefully this will help with the issues anyone has. PM me if you have any questions or problems. Bill, if you could move this to the tech section that would be great.

This is a picture showing where I mounted the voltage regulator, below the wiper panel on the passenger side of the truck. This works great because it's grounded and tucks up in there nicely. I used a Ford style external regulator from O'Reilly's, part number R400 cost $14.99. It can be seen here:

Item Detail | O'Reilly Auto Parts

Viewing from the top down, wiring connected to the regulator is: alternator field connected to upper post, switched power, alternator positive (output).

This shows the alternator connections. The first thing I did was unhook all the original electrical connections from the alternator. I then took a wood chisel to the little black molded box and broke it apart to reveal the individual ground and alternator output cables. Then, pull apart the wire loom that runs over the upper alternator mounting bracket that has the two wires connected to the original alternator field, and cut, heat shrink, and tape them. Re-install wire loom over those wires. Now, the 2 little green and orange wires need the ends cut off, heat shrinked, and taped. You can see them zip-tied to the alternator ground cable. The rest is easy, take the wire connected to the top post on your regulator and run that to the upper field connector. In my pictures that is the orange wire. The 2nd wire down on the regulator goes to switched power, I used the same lead that I power my pyrometer with. The final wire goes to the positive (ouput) wire on the alternator. Lastly, you need to ground the other (lower) field post. I looped a short wire from that post to the ground connector on the alternator case.


A few Fummins trucks, a commonrail, and some TDIs

Last edited by illflem; 04-06-2010 at 11:33 AM.
Shocker444 is offline  
The Following 18 Users Say Thank You to Shocker444 For This Useful Post:
12vbigkermit (05-20-2012), 24vcumminsgirl (09-18-2014), 96cummins 2wd (10-05-2012), 96_cumminsPower (04-08-2011), alonzojohn (01-26-2013), Big Dirty 05 (09-14-2014), dieseljunkiejoe (01-06-2012), dieselscout (10-23-2013), GNBEAST (04-12-2010), hillbilly cummins (08-12-2011), iblowsmokeintexas (01-24-2013), maddogs dually (04-07-2010), michael thorn (06-04-2011), raclash (11-19-2011), slickrock209 (09-08-2011), Smokes when she drinks (07-09-2016), theturbominivan (03-18-2012), WFO (11-19-2010)
Sponsored Links
Closed Thread

Quick Reply

Register Now

In order to be able to post messages on the Dodge Cummins Diesel Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Please enter a password for your user account. Note that passwords are case-sensitive.


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:


Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.

Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode

Posting Rules  
You may not post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

For the best viewing experience please update your browser to Google Chrome