Can anyone tell me with certainty where the voltage reg is in a 93 Dakota v8? I was told previously it was part of alternator, but that is not the case. New alt. has sticker that says "externally regulated". Don't see an external reg on the firewall. My problem is amp guage jumps up to 18 intermittently and lights brighten up, wipers and fan speeds up. Blew high beams out one night while driving. I suspect VR???

 

Its the little black box that bolts to the back of the alternator with two little nuts. Its the initial part of the wiring harness that hooks to the alternator.

 

Nope, not the black plastic thingy on the back of alternator.
Finally confirmed through Dealer service, it is in the ECM unit. Mounted in engine compartment on passenger side above wheelwell. Replaced ECM and fixed my Amp spikes. I'm pretty sure VR went out when I was towing (first time) a small trailer and running 12vlt fridge, lights, etc. Dak did not have factory tow and was running 90 amp alt.
Everything working fine now!

 

Well ok then.

 

Yes, I can with absolute certainty. The alternator is regulated by the ECM---The main control computer. Now it is also possible the alternator may have a rectification diode going out which will give you an incorrect voltage due to incorrect signal chopping. If you put a voltmeter on the battery before starting the engine, you'll see "xx" volts, usually around 12.5 or so. Then when it is running, if the voltage goes up at all, chances are the ECM is ok, because it is trying to charge the battery. It could also be a bad battery. Verify the charging circuit first, whether it works or not, and how much, then consider the battery. You will need a multi meter to do all this, preferably one that reads in 10ths of a volt. They're relatively cheap, and you can get them almost anywhere these days.

Hope this helps