75 Electrical Questions

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Greetings all, I am so glad I found this place... A little history

I have recently decided to give up on the "rolling plastic mistakes" that crowd our streets and cost a fortune to fix after sinking $4000 into my Xterra just for its 100,000 maintenance and decided to go back to my roots and pick up a beater.

A beater I did find... A 75 C10 shortbed stepside in need of some serious love, body is rough, interior is missing but i have been spending the last 2 months getting the motor and trans rebuilt and now it is making some nice horsepower and is quite fun to drive. I have been aquiring parts as I can find them on craigslist and ebay and tonight started on getting some safety issues resolved. Mainly no dash cluster, and no turn signals.

After spending a few hours on it tonight I got the turn signals working, and installed a instrument cluster I grabbed on ebay out of a 79. Tach works, fuel works, oil pressure works, Volts do not.

As I understand the 75 had a Amp gauge in it originally. So my first question is , what wiring changes need to happen to convert it to a Volt gauge? The wiring harness in this thing is rough, and looks like it was put together by a monkey with a butter knife, so any in depth info will help.

2nd question, which goes with the wiring harness being a mess. The dash lights all work, the only problem is that they work ALL the time! As soon as you turn on the ignition the dash lights come on. The light switch has no effect on them turning on and off or diming. The dimmer will turn on the dome light under the dash, but has no effect on the gauge lights or heater control lights.

Any help for this NEWBIE would be greatly appreciated

[87 STEPPER]

To the board

Thats a good lookin' Truck you got your self.

The simplified version is to remove the guage cluster and find the wire thats for the lights and follow it back to where ever it terminates i would bet someone hooked it into the fuse block to a SW. IGN. port. unhook it and rewire it to the light sw. you may need to buy yourself a manual with some wiring prints in it to find out what post to connect it to.

As for the volt meter you can just run a fused wire right to the Alt. and the other one to ground. thats it.

Good luck

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Thanks for the help!

I went and grabbed the Haynes guide this morning as a little extra support, but you were dead on.

The guys who built this thing had no idea what they were doing. The green wire coming from the headlight switch to the fuse box was in the right spot, the grey wire coming from the fuse box to the dash lights was right, but they had wired the ignition post on the fuse box directly to the post with the grey wire which in turn had fried the headlight switch Picked up a new switch at Napa for $12, fixed the wiring and good to go.

The Volt gauge was easy too, cut the black and black stripe wires from the cluster harness, spliced in a 4amp inline fuse on the black stripe and hooked it to the igintion post on the fuse box that had been so clearly pointed out by the previous botched wiring. Threw a spade on the black and grounded it with the other harness ground and voila, working Volt gauge.

Next step is swapping the steering column, which is also going to be a treat. The ingition switch on the column is broke, so the key only operates in accesory and the running position. The previous owner wired a push button ignition button under the dash, which is kinda cool in my mind. I think I am going to keep it but move it up onto the dash, kinda have a race car feel to it.

Again, thanks for the help, I am sure I will have more questions as time goes on, but thats half the fun of saving a 31yr old truck from the junkyard

[lurch115]

Painless wiring also makes replacement harnesses...that might be easier for you

[84 400]

welcome to the board and nice "beater"