External voltage Regulator issues

[Orangepeel]

My 91 d150 5.2 has an integrated ecm controlled voltage regulator. It is failing. So I figured I’ll install a voltage regulator externally and by pass that ecm garbage. So I cut the green wire which is ecm to alternator and took the blue ignition wire wired it to the voltage regulator and to the alternator. The other side of the alternator I went to the voltage regulator. The battery + wire is still factory and hooked up to the alternator and I have the factory ground attachment wired to the alternator body as well. It doesn’t charge. If I take the ground side of the wire off the regulator and ground it to the alternator it will charge and full field the alternator.
When the truck is running I have power on both sides of the regulator but only battery voltage (not charging voltage. I followed this wiring diagram so I’m unsure what I did wrong. Any help is appreciated.

 

[mk378]

The regulator case must be well grounded for this system to work. Also those regulators were not real reliable.

 

[Chris142]

X2 on grounded regulator body

 

[Donald]

How about a alternator with an internal regulator?
I'll bet a starter/alternator rebuild shop could fix you up as long as the guy working there was old.

They should have normal alternators that need sense & excite in addition to battery and single wire alternators (sometimes called hot rod alternators).

 

[Cujet]

Sounds like the regulator is not working. Try another. Measure the output of the regulator, I'm guessing it is 0. There are kits that are designed to replace failed ECU voltage regulators.

$22 gets you a conventional voltage regulator that will work. $65 gets you an adjustable unit that is specifically designed for chrysler vehicles with a failed VR.

 

[eljefino]

The regulator case must be well grounded for this system to work. Also those regulators were not real reliable.

All of this. IDK where you stuck yours but the factory position on the firewall is painted so you need to scrape some of that off.

 

[Orangepeel]

All of this. IDK where you stuck yours but the factory position on the firewall is painted so you need to scrape some of that off.

I ended up replacing the regulator and it works now. I got a bad master pro regulator out of the box. I did scuff the paint off with a sand disc on my angle die grinder