Wiring Aftermarket Gauges

I am installing an Autogauge 2 5/8"gauge pod (water temp, oil pressure and voltmeter) and tachometer in my '75 318 Duster as part of my "Day 2" look build. I've the mechanical part done, now starting on the electrical hookups. Does anyone have suggestions on what wires to splice into for the lighting and switched power? The fuse panel isn't marked and I don't want to randomly start splicing into the almost 50-year-old wiring harness. Thanks!

Do you have a service manual? If not you can download one. Teh 73 or 72 manual might get you close to find a circuit to test.

Service Manuals – MyMopar

When I added gauges, I added a remote fuse block in the glove box to power all my Auxiliary stuff like gauges, stereo, etc.

I went direct to the dash light fuse

dano said:

Do you have a service manual? If not you can download one. Teh 73 or 72 manual might get you close to find a circuit to test.

Service Manuals – MyMopar

When I added gauges, I added a remote fuse block in the glove box to power all my Auxiliary stuff like gauges, stereo, etc.

Click to expand...

Thanks for the link. I like the idea about an auxiliary fuse block!

Usually the orange wire on Mopars is the dash light circuit.

middleagecrisis said:

Thanks for the link. I like the idea about an auxiliary fuse block!

Click to expand...

On the one I used from Painless, the only thing from the stock wiring was to trigger the relay, the rest is all sperate.

On the top side is a power bar can tap in there run you own fuse and switch, Or with a relay/fuse and run a wire from the light switch to turn on relay.

You probably already know your 75 model has a white fuse box with about twice as many fuses as the earlier black 5 circuit fuse box shown above.
If this is a gauge pod that mounts under the dash, like under the radio maybe, All the power you need is right there at the radio and already fused. The orange wire for lighting can be found at the lamp in the top of the radio, or at the ashtray lamp (if so equipped). This allows the instruments to brighten and dim like all other OEM illumination.
Without a 75 manual to reference, I'm going to say the power connector to your radio has a red wire and a white wire. Both are switched hot (white is just extension of same fused circuit. I forget if it went to turn or reverse lamps).
I think adding fuses and relays for a few gauges is overkill. Just properly tap the power sources and install male/female connectors so they can be disconnected if needed.