Hello all - new to the forum. I have an '07 Dakota SLT with a charging issue and could use some help please. I've read through several threads on here but still haven't resolved my issue.

A couple weeks ago my battery light would randomly go on/off (this went on for a few day), then the airbag or ABS light (don't remember which) also started going on/off. Finally on the way home from work, the batt light, then ABS, Airbag and a few other lights all came on and it started running rough, so I pulled over and it died shortly thereafter - had it towed home. So the next day I put the battery on a charger, and finally took it to O'Reilly and had them check the charging system. The guy said the Voltage Regulator was reading bad and he's the one that told me it's in the PCM but you can bypass it. So I found a video and blog about bypassing, ordered parts and used the following diagram to build and wire it up. I have it all wired per the diagram and the two loose wires going to the PCM have been connected to a 194 bulb (per info I found in this forum) so the CEL doesn't come on - though it has not been coming on during this anyway. I have the center post running to the power outlet fuse in the fusebox. It starts up and runs fine, but is not charging and the batt light is still on. After I connected the bypass, I took it back to O'Reilly and it was still showing a VRM fail. I went ahead and replaced the alternator anyway thinking that maybe the bad VRM messed it up, plus I accidentally shorted the positive to the front of the alternator when assembling and checking - that was fun. I have also replaced the external VRM from Amazon with one from O'Reilly. But, it is still not charging. I confirmed voltage from the fusebox to the VRM with my multimeter. But when I check from the postive batt terminal or the charging wire from the brand new alternator, I'm getting less than 12V (about 11.69 if I remember). My battery was replaced back in Feb with an Interstate battery from Costco.

What am I missing here? How can I narrow down/fix this issue? Thanks in advance for the help.


d blog about bypassing and buil

 

My experience with voltage regulators is entirely with 120v output, but they always have an adjustment screw for fine tuning the output. One weird thing I have seen is certain brands/style of regulators just simply not working as they should in certain conditions. Brand new regulators that would always be outputting a lower than required voltage, not matter what we tried they were also low by 10%. Is there anything in the documentation of the regulator you installed, or in the blog post?
If you link to the post I can go through and see if there is anything I can find.

Edit: if it is the vr-125, it is a transistorized regulator and cannot be adjusted.

 

There is one available with a voltage adjustment, but neither of the two I've tried have the adjustment. They also have different ohm readings. But I find it hard to believe that two different VRM from different manufactures could both be bad.....

 

I've dealt with some that were recommended by the manufacturer of a generator, it's in the documentation, it ships with the unit, they test it with that exact vrm, but we couldn't get it to work with three new regulators. As long as there is a good ground and it is wired like the picture, it should be working. All its doing is turning on an off the feild coil. I'd try one with an adjustment screw, or test your battery. A bad battery can cause some issues with voltage regulators.

 

I think I found some info on the issue.


In the video there are two types of alternators used for dodge vehicles. Only one of the pins is used for the field and the other is not used. Also referenced by this photo of the pin out from rockauto for a 2007 4.7l dakota. I believe the video referred to them as type A and type B regulators. It's possible you need a type B.