19stang66

So I returned the ugly Summit brand tach I initially bought and got the Sunpro Sun super tach II. Man I love this thing! It looks sooo good with the rest of my gauges.

So anyways I need help with some of the wiring. In the directions it says to hook the red wire up to "any vehicle harness wire which is energized with battery voltage ONLY when the ignition key is in the ON (RUN position, NOT OFF or ACCESSORIES)." So what wire do I need to splice into? They give you these cool red connector things that i've never used before (See pics).

I also don't know where to hook up the white wire (for lighting). The instructions say "Connect the white wire to the instrument panel lighting circuit or any lead that is controlled by the instrument panel dimmer switch." They show using the red connector thing for this one too. (See pic) So what wire do I need to splice into for lighting?

MidNite27

The red wire is for the Tachs power. It wants to be on only when ur keys are in, that way ur not sucking ur battery dry. You need a voltmeter and just stab some wires untill you hit a 12v wire that only gets power with keys in ignition. Or you could get power from your ciggarette lighter wire, which is 12v and requires keys to be in.

The white wire is the tachs backlight, which will be wired up to a 12v wire which turns on with the dashlights. That way u turn on ur dash lights, and ur tach lights up as well.

As for the connectors they are known as T-Taps. You slide the fully hollow part over the wire you want, then slide the wire for the tach into the blocked passage and crimp the metal slide through both wires. This connects them both of them together.

19stang66

So when crimping it, do you actually cut through the wire? or how does that work?

Soaring

The cigarette lighter is constant voltage on your 66, so that's not a good spot to hook into for the + red wire. Either hook into the ignition switch itself, or the radio + wire. Those crimp things work OK, but I prefer soldering the wires together and then slide a tube of heat shrink over the connection that you need to slide onto one of the wires before you solder. Then hit the heat shrink with a butane ligher and it will seal it from moisture and make a very clean looking joint.

19stang66

I have an aftermarket radio and I have it hooked up so it only turns on when I press the power button. So that wouldnt work, or would it? What if I bought some switches from Radioshack and spliced them in the red wire and white wire and had those two wires hooked to a constant voltage? Then I could flip the switches when I wanted the tach on and the backlight on. Or would that be way too much work than what I need to do?

MidNite27

Then u'd have to mount the switches (possible cutting) and always be flicking them when u want the tach to be on, and if u forget to turn one off, u will kill ur battery. I'd rather have it automatic so ur tach light turns on with all ur other gauge lights at the same time, and u turn ur key and it gets power along with everything else.

Seems like alot of extra work. With the switches: Cut, Mount, Find power wire anyways, battery risk, and more wiring.

Sorry about the cigg lighter suggestion, didnt know it was constant power.

6mustang6

Yeah, just get under the dash, by the ignition switch. using a light, find a wire with power with the switch on. I installed the SAME tach not too long ago.

daver

You will also need to hook up a wire to the postive side of your coil and another to somewhere on the engine as a ground.

6mustang6

Negative side of the coil....., and you dont have to have the ground on the engine. I just ran the green wire to the negative terminal on the coil. I ran the ground and everything else, under the dash.

19stang66

Yea its the neg side of the coil. I got to the ignition wiring and none of the wires seemed to give any voltage, and yes I had a good ground. I just ended up stabbing myself a couple of times with the voltmeter. When I did get into the wire, the interior lights would just dim and the red wire on the voltmeter would get really hot.

6mustang6, if you installed the exact same one and since we have the exact same year, couldnt you just tell me what wires you spliced into???