So, my son has a 75 W100 Club Cab, he's driving down the road last weekend and every gauge in the dash pegs to the right side, he pulls over and calls me and I instruct him to quickly pull the fuse. Soon as he removed the fuse all the gauges dropped to the left peg, put the fuse back in and immediately they go back full right. Since the turn signals are on the same fuse he now has no signals or gauges with the fuse removed. I've spent the last few days chasing wires, pulling the fuse box, replacing fuses and I'm officially stumped...anybody got any ideas? Help please. Thanks

Bad voltage regulator for the guages. You should be able to pull it and reinstall the fuse. Gets you lights but no guages. Iirc the regulator is still available.

Is that going to be the little unit that looks like a points condenser?

It's on the back of the printed circuit board. Kind of looks like a points condenser I guess but more of a rectangle. It's held in with blade terminals, no wire connections. Easy to replace if he can reach it, just have to lay on the floor and reach up to get it though he probably won't be able to see it. Probably just as easy and better to pull the cluster and inspect for burns/resistance etc., especially on the ammeter connections. He should be able to pull it out just far enough without having to disconnect stuff.

Today is your lucky day, I took some pics so you can see what to look for. First is is of the V.R. itself, second is of the circuit board with the empty slots and third is where it gets installed.

That part is 1/2 the price of that Year One link at lots of other suppliers....

the local parts store should stock it.. Autozone does.

I'm surprised auto stores stock that part! I don't think I've ever replaced one in the 40 years (and probably 100s of Mopar cars & trucks) I've been driving Mopars! Maybe I've just been lucky? Gene

I've never replaced one either but I suspect a few of my cars needed it. The '77 truck I just picked up might need it. The amp gauge flutters.

This regulator has nothing to do with the amp guage. You may have bad connections or a failing alternator or charging system voltage regulator.

Holy smokes, thanks guys this is awesome information! I actually think I may have a spare one in a box of old truck instrument panels somewhere, guess I know what my son and I will be doing tomorrow...standing on our heads underneath the dash of an old Dodge truck...thanks a bunch, I'll report back my findings and fixes

Check this page out. More info on voltage limiters than you would ever care to know.

http://rt-eng.com/rte/index.php/RTE_Limiter_Faq

That may be.. I'm busy fixing just about everything else right now so instrument woes aren't a priority for now.

Yep, all you can say after browsing through that is WOW...lol

Update!!!! Pulled one off of a spare instrument panel I had and installed it...bingo! Gauges returned to normal. Thanks for the information and help! Awesome!