I'm trying to wire a tach into my 78 and am kinda stuck on how to physically connect to the fuse box for the red and white wires. There aren't any obvious connection points for adding a connector or wire. I figured I might just have to splice into the existing wires, but wanted to see what others have done for the older trucks.
I would likely splice a wire off the 15A lighter circuit. I think it’s the 3rd one down? where have others wired accessories for switched power off their fuse box?
Yeah I've got t taps I just don't like the idea of them haha. They were what I was going to do but I wanted to ask if someone smarter than me has come up with something I can't remember what it was called, I'll check when I get home from work. I was looking to connect power to like third or fourth from the bottom I think
So i had about a half hour to work on this last night and hooked up the power/lights/ground wires to test it, but as soon as I reconnected the battery, the backlight on the tach came on.. I ran the red wire to what was labeled "IG Coil" and the white wire to "Lighter room". I checked the owners manual and it actually had different but similar names than what was on my fuse box. I couldn't find my multimeter to check voltages, but I'll try to find it and do it tonight. I thought I had wired the red/white correctly?
Be careful on which side of the distributor you power from. You could damage your electronic ignition. Old school says attach the (+) from tach to (-) coil terminal. Ground wire from tach to any body ground. Easiest way would be to run a new wire from coil (-) to wherever you’re installing your tach. Also, be sure your tach is designed for a 4 cylinder application.
Yeah I know the green wire goes to the neg side of the coil, I didn't connect that wire when I tested it last night. My tach (Bosch) has a selector switch for the number of cylinders and it's set on 4
You saying green wire is telling me its an aftermarket tach. Tap the + to the *Heater/Gauge* fuse, then Ground and tach signal. Connect the light to the ign source too fckit just to simplify the install and go on about your day. Just knock out the install.
