Black and red 12G wires on instrument cluster

[72RoadrunnerGTX]

The pictures are of a spare cluster that came out of a car I drove for several years and then parted out almost 30 yrs ago. Never had electrical problems with it even though the insulator is missing a corner. I doubt it had ever been apart before - certainly not by me, but I didn't see the missing piece in the housing. The ammeter actually mounts to the circuit board and not the housing itself. Nuts on the back were snug, but not tight - I removed them with my fingers.

When I restored my Satellite in the early '90's, the insulator disintegrated when I disassembled the cluster so I scavenged one from another spare. More evidence that this is a delicate part that's easily damaged if the cluster has been disassembled. I didn't remember the nylon washer/bushing from before, but it's likely also important for isolating the gauge from the housing.

If you look closely, the back of the circuit board is stamped RED above the left ammeter stud and BLACK above the right one so you know which way to wire it.

I had a ’66 Sat many years ago, should be the same cluster. The white telltale rectangular pattern on the inner insulator shows it does mount up against the inside of the cluster frame, can see in one of your shots the raised lip around the single rectangular stud pass-through hole, with tabs at each end to locate the insulator centered over the hole. The PCB on that cluster would then double as the outside insulator, nylon washers would likely be protecting the PCB from damage from the stub nuts. Not sure I can agree that the fiber insulators are all that delicate, not by my experience anyway, only ever seen obvious heat or physical abuse damaged insulators, have quite a few used original insulators in as new condition. That insulator material was, and may still be, widely used in electrical of all kinds, going back decades.

There is usually some indication on all ammeter clusters what wire connects which stud, in the E-body cluster pictured above, “RED” is cast into the cluster frame.

 

[440 PHIXX]

I just put both lugs on one post in my wagon when the amp gauge started acting up. And yes… the FSM doesn’t show many grounds. My brother’s ‘70 Challenger had a discharging battery problem that no shop could fix. It turned out to be the voltage regulator ground to the firewall.

 

[1 Wild R/T]

The ammeter actually mounts to the circuit board and not the housing itself.

True on B bodies.. E bodies don't use a circuit board..

 

[Nacho-RT74]

71/74 B body standard cluster is also PCB. Rally clusters are not thought.

I never have seen any kind of insulators or protection washer on the outside of the cluster on PCB assemblies since the PCB already serves as an insulated surface per se.

 

[Nacho-RT74]

I don't how to determine a good ammeter vs a bad one, or what insulators I'd be looking for.

A bad/damaged ammeter will be easy to diagnose just watching at it. In some cases (if not most of them) are easy to fix/reinforce.

The insulator piece is a very standard piece along the Mopar models ( ammeter specs and stud gaps uses to be the same ) and years and Performance car graphics ( as far I recall ) sells repros of these. Can be home made thought getting the material.

So for now, I'm want to sneak up on a solution, one thing at a time. From the image above (72RoadrunnerGTX) of the damaged ammeter I can assume mine is damaged in some way. So back to my earlier plan and that is to replace the ammeter, put my red and black wires back and I should be good.

once again, you won’t know untill remove and check.

 

[Nacho-RT74]

and Performance car graphics ( as far I recall ) sells repros of these. Can be home made thought getting the material.

my bad, this is the seller

ALL Car Lines Ammeter Insulator - Premium Dash Decals by Mr.Heaterbox

it seems this is the manufacturer?

Dash Circuit Boards — Mr Heaterbox and Interior Restoration Services

 

[72RoadrunnerGTX]

71/74 B body standard cluster is also PCB. Rally clusters are not thought.

The PCB on that cluster has nothing to do with the ammeter mounting or insulating.

 

[Nacho-RT74]

Sure… but I never said the PCB on them gets the studs over the PCB LOL. I meant that because the previous comments about clusters with circuit boards.

forgot to attach the pic thought LOL

 

[copper67sat]

I had a ’66 Sat many years ago, should be the same cluster. The white telltale rectangular pattern on the inner insulator shows it does mount up against the inside of the cluster frame, can see in one of your shots the raised lip around the single rectangular stud pass-through hole, with tabs at each end to locate the insulator centered over the hole. The PCB on that cluster would then double as the outside insulator, nylon washers would likely be protecting the PCB from damage from the stub nuts. Not sure I can agree that the fiber insulators are all that delicate, not by my experience anyway, only ever seen obvious heat or physical abuse damaged insulators, have quite a few used original insulators in as new condition. That insulator material was, and may still be, widely used in electrical of all kinds, going back decades.

There is usually some indication on all ammeter clusters what wire connects which stud, in the E-body cluster pictured above, “RED” is cast into the cluster frame.

You are correct about the inner insulator mounting against the rectangular frame. For some reason I was thinking the insulator went into the rectangular recess when I posted this morning. Should have had coffee first lol.