67mustang302

The trigger wire has to go to the tach output on an ignition box if you have one. I dunno if it'll even work if you don't, but even if it did, your tach would read about 5-10 higher than it was under 3,000rpm if you use the coil as a trigger with an msd type box.

adr3naline

So, I attached the red wire to the ASSY bolt. I attached the white wire to a dash light wire that controls the light at the heater controls. Nothing is working. The green I've routed to the (-) negative side of my ignition coil. The black I've grounded to my chasis in the engine bay.

What is wrong? Why isn't it working?

noroof66

Looks like you did it correct. Check your fuses, and if you have a meter, put it on there to double check power.

noroof66

BTW, Is it at least lighting up when you turn on your lights? When you say not working do you just mean the needle?

67mustang302

THE TACH LEAD HAS TO GO TO THE IGNITION BOX.

[>:]

adr3naline

Nothing is happening. It's not lighting up, and the needle is not moving.

67mustang302, is the ignition box the same as the ignition coil? I've got that right.

67mustang302

No, if you have an MSD/Mallory etc box hooked up to the coil, the tach MUST be connected to the output on that to read correctly. Make sure your ground is good, if you connected it to the underside of the dash etc, it may not be closing the circuit. Also, are you sure the red is hooked to a 12v switch? And youare checking with the engine running, right?

noroof66

Even if it is not connected correctly at the coil, it should still light up if the other wires are correct.

adr3naline

Okay, this Tach is really starting to make me mad.

I've attached the red to the ACCY post at the fuse box. I've tested the connection, and I get power there when the car is in run.

I've attached the white to a dash light wire, again, I know I'm getting power when I turn on my lights.

I've attached the green to the negative post on the ignition coil (is there a possibility that it should go to the positive side?)

I've tried grounding my black to multiple sources, but it's all the same.

When I have my car in "Run", and I'm testing ground locations, the needle is moving... What does that mean? Why aren't I getting any power to the tach even when I've tested my connections. What is wrong! I feel like JohnCalvin because I really don't want to take this to a shop for such a little thing. Could my tach be bessed up? When I turn on the engine, it's the same as if it wasn't on. No lighting, no needle moving, no power, etc.

bluovalguy

You have everything hooked up correctly. The only thing it could be is maybe one of your wires in the car is not working properly. Call summits tech line, maybe it is a bad tach. Try dry hanging it on someone elses car and see if it works.