Cool - got all hatches battened and lug nuts back on, fired up and drove it around yesterday, and all systems seem to be good to go 👍. One girl in a JK hollered out the window "that's the sexiest truck I've ever seen!", which made my day . R-rear hub is dry, exhaust is maybe a bit less loud - not as quiet as I'd hoped for but any little bit helps. Steers and stops just as good as it ever has. So yayee 👍 .

One nagging issue I've been tracking (and resolved this morning) was a 'pulsing' voltage regulator/charging system. Since day 1 the truck charged its two big deep cycle batteries fine...but when it's running...every two seconds or so you can watch the voltmeter needle 'twitch' - meaning it'll be at ~14.2 volts and 'twitch' off/on every few seconds like clockwork - like the charging stops(?) for a very brief moment - not even a second's worth of time - it's like a blip in the charging system...and it has done this ever since day-1 nearly 9 years ago. It reads normally and charges the batts 'fine'...but every 2 seconds the needle will 'twitch' and simultaneously you can hear the engine rpms 'twitch' too - a very slight but noticeable rpm drop, kinda like the alternator is 'demanding' more for a very very brief moment, dropping the rpms...at least that was my theory.

If the rpm's were up the issue seemed to eliminate itself - just as a data point.

Whatever the problem was has never affected charging of the two big batteries nor has it affected engine performance...and it does not seem to be mission critical, but I know whatever is causing the 'twitch' is not normal and I wanted it to stop. It's one of those things you can't 'un-notice'.

I recently replaced the voltage regulator - no change. I checked all the connections, and added another ground, but again, no change.

What did make a change, albeit a small change, was separating the VR's green field wire from both the 12v wire and the big charge cable off the alternator and wrapped them in separate plastic conduit - just in case there was any minor voltage 'bleed-over' from one wire to the other(s); it was still pulsing...but much faster - like every half second. Don't know what the hell that means, but apparently having the field wire and 12v wire running 'alongside' each other from the regulator to the alternator...along with the big charge wire...for reasons unknown...seemed to make a difference, but the base issue still remained. Also, on a voltmeter it's pulsing up to 15.2 and down to 14.8 back and forth...so it was technically overcharging.

One interesting actual solution (on another guy's truck) I read about on the interwebs was using a relay to 'clean up' the 12v sense wire power to the VR/alternator 12v inputs, so I tried that this morning, and...so far...it seems to have worked. Source power is now coming from the alternator charge terminal (with a 20a in-line fuse), 'signal-on' from the original 12v wire, output to the VR/sense terminal wires, and ground to the VR, and it now has no pulse and is charging at ~14.6 volts.

I think the charge rate is a bit high because the batteries may be a bit low, and I'm going to drive it around a bunch over the next few days to ensure all is working properly. It may have simply been a crappy sense signal all along - not enough for it not to charge, but enough for it to...well to do all of the above shenanigans.

One note - on this truck, there are two big powerful batteries...but they are located 15 feet away from the VR, and the frame completes the overall circuitry as the ground for 'everything'. Lot of distance in the wiring, and I think that is what caused this particular issue to begin with. This isn't the first 1st-Gen-Cummins-powered-truck I've done this external VR 'upgrade' to, and I don't remember this issue occurring in any of the others, but again this truck has the batteries way far away, so maybe that is why this happened to begin with. Just a data point for anyone else considering wiring in an external VR.

Diagram for easy reference -



Booyah 👍