73-87 gauges in 67-72

[69heavychevy]

I was wanting to use 73-87 voltmeter and temp gauges in my 69. Has anyone ever done this or is there a write up that I could reference??

[ETsC10]

69heavychevy, didn't see too much action for you so
lets ask the electrical gurus! Subscribed...I'd like to know too!

[69heavychevy]

thank you

[Pondscum]

sounds like a good idea, anyone figure this out yet?

[Pondscum]

i took the volt meter and water temp gauge out of a 78 sub i have for parts today and after doing some checking between the gauges and it seem that with a little nipping of the gauges out of the 78 that they will be able to work proly have to be a little creative withthe wiring but i saw no reason why a person couldn't do it and i plan on working on it when i get the time to

[69heavychevy]

Yea I already grinded them down to fit in the bezel, I just have to figure out how to wire them up. Whats making it a little difficult is I want to wire them up to my harness. I also need to figure out what the volt/ohms reading should be on the 73-87 gauges...

[VetteVet]

Do you have the 7 gauge dash with the battery gauge and the oil pressure gauge or the one with the idiot lights?

The ohms readings on the 67 72 temp gauge is in the 80 ohms range and the volts will be 12. The voltage gauge will read the voltage potential between the negative and positive posts on the battery plus the alternator output when it is charging. In other words it will read the system voltage. The ohms reading will be next to nothing since the VM does not draw any current.You can wire the voltmeter to any positive and negative sources and it should work. It will have to be grounded to the vehicle though because the needle coils need a path to ground in order to deflect the needle.

If you have the battery gauge and the wires were intact and the two fuses were good, I see no reason why you couldn't use them as long as you grounded one of them and wired the grounded one to the negative terminal on the VM. These two wires go to terminals 1 and 12 on the dash plug and one is black and the other is black with a white stripe. The downside to this is that the VM will not be keyed on but it will draw so little voltage that it shouldn't be a drain on the battery.

The easiest thing IMO is to wire the VM Positive terminal to the pink wire that comes in to terminal 3 on the dash plug and runs to the fuel gauge, and the other gauges in the dash to power them (see the diagram below). Then just ground the negative terminal to any good ground i.e. the dash itself. This give a key on voltmeter. Be sure to insulate the old battery gauge wires as they are full time hot on the engine side of the firewall.

The temperature gauge should just go in place of the 67-72 wired to the copper strip. be sure to insulate the two terminals like they were in the stock dash. If the sender is the same ohms range as the 73-87 it should work just fine. It is the second from the right and notice the vertical posts are insulated from the dash. The horizontal terminals are for the power and the sending unit wires.

This is the dash gauge I'm referring to.



Here is the backside showing a red wire takeoff for tachometer power from the fuel gauge. You should be able to use it for the voltmeter as well. Then just ground the negative post of the voltmeter to the dash or any good ground.



Here is the dash plug arrangement for the stock dash 67-72. Notice 1 and 12 are the connectors for the battery gauge. Terminal 6 is for the green temperature gauge sending wire.



This is the diagram of the two battery gauge wires with the fuses and the shunt in the wiring that the battery gauge measures. Note that both wires are connected to full time hot junctions.

[69heavychevy]

Thanks Vettevet for the info. Been pretty busy the last few weeks so its taken a while to get everything going. Have all the gauges mounted and ready to go, now I just have to get the quartz clock mounted. That one is a little tricky but once im done i'll post some pics (hopefully later on this week).

[Pondscum]

any luck wiring the gauges up? I got the voltmeter workin in my 72 but i'm still havin issues with the temp gauge was just wanting to peek over your shoulder and cheat a bit to make sure that i did it right