Well...that NOS speedometer is expensive. But at least it will work. Removing mine left a pile of tiny springs and a broken needle. Not the best thing ever, I'm afraid.

Now: I have an RTE solid-state relay en route, but can somebody tell me what the two wires could possibly be doing here?

Black runs from right prong and grounds underneath the radio.
Red runs from column to one of the mounting bolts of the radio.

I cannot imagine what purpose the red wire has. Did they believe they were grounding the radio?

As far as NOS speedometer goes that's actually not expensive for NOS speedometer. They've gone through the roof lately. There's another NOS one speedometer on feebay for $250 and a used one for $60 which I'd never buy a used one, then one here for $140 http://www.dpmotorparts.com/list_parts.cfm?page=273 Here for $275 https://www.hiltopautoparts.com/pro...6-chrysler-plymouth-dodge-b-body-models/

No none of them are mine lol

wiring:
ok, the red from column to radio does absolutely nothing. it doesn't connect to the metal of the radio case or the dash frame so it's pointless. the black one going from the dash vr to a ground is an attempt at adding a ground to dash ckt board or vr specifically. Need book to check location, where to test for what it's trying to do. probably pointless attempt to fix gauge. oem radios have a ground lug on the back. some years a stud, some years a nut, many years a rear support bolted to it.

speedo:
in this skin, 75 only, also used in 74 and maybe 73. I have a couple working ones stashed, I'll hook ya up., remind me.

hey, balance knob missing entirely? I mean knob not unusual but entire lever gone??

this one works, have the floor button.

Balance slider is completely MIA. I'll hold off on the radio replacement for the moment, the gauges are a much more pressing issue and I need to do speakers as well, later on. If a 1974 will work, will a 1971 work? For that matter, wonder how well an entire 1971 gauge pack would transfer over...hmm...

Hopefully my books show up sometime this week.

earlier gauges won't fit. the jumper from column to radio could be doing something - some years the radio mounting tab is part of the chassis, most years it part of the plastic face plate. it's still a hack fix for the whatever the actual issue is.

'71-'74 B-body gauges will not fit?





Exactly. Maybe it's just glare in the photo, but the photo with the red wire looks like the tab is cast as part of the front of the radio chassis. I still would recommend this method, but it's not total insanity.

Work was performed this weekend. Old voltage regulator is out, a new RTE IVR3 limiter went in. NOS speedometer went in, cable lubricated. The results: the speedometer works like a charm. The fuel gauge now reads slightly over 1/8th tank when fully topped off and drops fast. Everything else can't be bothered. And that's with the two odd wires both hooked up and not. All that seems to happen is if I unhook the red wire from the column, my seat belt buzzer quits working. I do wonder if the sending unit in the tank is moving properly, but as far as everything else?

'71-'74 B-body gauges will not fit?

Hmmm... I remembered this thread and pretty sure they fit in the later clusters. From what I remember the earlier speedometer is smaller if I remember correctly. https://www.forbbodiesonly.com/moparforum/threads/71-74-b-gauges-in-a-magnum-cordoba.45211/

74s should, 73s might, going back earlier ya run in to size / mount / font issues.

Ok, so jumper from column to radio is for seat belt buzzer. That's freaking odd. Seatbelt interlock noise is mounted between ash tray and glove box, should be grounded as needed to metal frame. I still say loose them and chase the real issues.

Gauges run off variable resistors - fuel sender is 0-90 ohms, dunno exact resistance of temp and oil. In all cases, ground the gauge lead at the sender and the gauge should read max. From there it's chase the wires, connectors, senders and grounds. Only time I see temp and oil refuse to move is unplugged at the sender. Gas sender generally has a horrible ground making it read low.

More work has been done. Popped the sensor wire off of the temperature sensor, ran a ground to the battery, and hit it with a AA battery with the wife in the car watching. Nothing, not so much as a twitch. I believe the gauges are cooked. This leaves me with the new speedometer and the fuel gauge that reads 1/8th when the tank is topped off.

This also leaves me at a bit of a conundrum. I want to keep the OEM feel of the car, but I really want a Rallye cluster in the car. At some point, I am going to pull the whole dashboard out so I can send it off to Just Dashes to get the crack in the dash cover repaired. I would be somewhat alright with just a functioning speedometer and fuel gauge for the time being, but I wouldn't be completely comfortable on longer trips like I want to do. (read: RMRW, Power Tour, etc.)

For now, I'll watch eBay and start poking around. Any other ideas that I could try out, let me know. Once this tank of fuel runs low I'll drop the tank and have a look-see at the sending unit. I appreciate all of the help!

Hooked a AA battery between the temp sender lead and bat ground?? Ummm, no. Jumper the temp sender lead to ground and turn on ignition, check for needle movement. When the voltage limiter for the gauges goes poof it can fry the gauges but like I said, don't often see that. A simple ohm meter across the gauge leads should tell you.

This bit is easier if you have the wiring diagram but ya can do it blind if ya really have to. Pull all the gauges out of the carrier, figure out which clip on each one is ground. Run an ohm meter between the other clip and the sender lead. There's a connector at the gauge cluster that can cause issues but usually doesn't. Same with the bulkhead disco. In the case of early 76 build there's another disconnect on the passenger side wheel house.

The Rallye dash is kinda nice to have from a rarity standpoint - if you can find a tach with the needle still attached. Used to be a pretty cheap score at swap meets and bolts right in. I find the gas gauge hard to read in part because it has about 1/3 the sweep of the regular gauge. I might still have most of one stashed away and more than likely have a lower bezel. Lemme know if ya want me to dig.

*squints*

...is that a 140 MPH speedometer?!

yup - fury / coronet cop car certified speedo. real tough find.

I started wondering what I had left and have been wanting to catalog the bits so 2 birds, 1 stone.

1st one: 75 only, complete standard dash, working when pulled. No kmh scale.

2nd one: 76, 77, complete standard dash, dual scale speedo US, blue trim on cluster mask, bezel is 78/79.

3rd one: 78/79, complete tach dash, 76/77 speedo random bezels

a couple of 75-77 tachs

As long as I'm at it......

75-77 tach vs standard: different gauges, different circuit board, different carrier, same wiring harness, direct plug in swap.

78-79 tach vs standard: different gauges, different circuit board, same carrier, wire harness might be 75-77 plug compatible.


This is the early vs late tach dash circuit board. Early ones had a stand alone harness for the tach, late ones had it built in. Also switched the tach mount to the same push pin arrangement as the other gauges.

Oh yeah super tough to find!

I did actually score one in a boneyard once. The one pictured here was an NOS find complete with red 1/10 digit. Would ya believe $77 shipped from Island Dodge in Hawaii?

More testing done, since the car is currently sitting with no fuel tank underneath it right now. Pulled each gauge and tested individually except for fuel gauge. Happily, with the tank and sender removed, the LED warning light for low fuel has come to life. All gauges show life bench-tested, which rules out a load spike death. I cleaned the gauge contacts before reinstalling them.

This leaves me with two options: the cluster connectors themselves, or the bulkhead connector. I've pulled both cluster connectors, cleaned the terminals, and have made sure the contacts are good. How likely is it that the bulkhead connector has an issue?

The bulk head connectors are always a possible problem area. A lot of it depends on where the car spent most of its days, damp cold storage often causes issues with the bulk head connector.

I bought a 75 Daytona Charger that spent a good share of its life in a wet garage. I had a hit or miss electrical issue. After chasing it for several months, I discovered that somewhere along the way, the bulk head connector was separated and cleaned, but when it was reassembled, they didn't get all the spades pushed completely in. The car would run great until it would die on the road. About the time you started checking things out, it would fire up, and could run for a month or more before it died on the road again. One day, out of frustration, I took a screw driver and pushed in all the wires in on the bulk head connector, about 1/2 of them pushed in at least an 1/8" . Never had a problem with it after that.
Check the bulk head connector! Gene