I am putting my tach back in and had to cut off the pigtail connector. Can someone remind me where the 3 wires hook to the back of the tach. the circuit board has two prongs on the top and one on the bottom.

thanks,

 

 

Hey that picture looks familiar to me!

Willcox

 

Ernie, I couldn't remember where I got that picture till you posted. Thanks for the use of it.:o

 

No problem, you beat me to posting it.

Willcox

 

Just what I was looking for.

Just so I make things correct in my car, the positve is switched 12V, the negative can be grounded to the cluster? The tach signal is going to be coming from my LS PCM. I may have to try this out one night this week if I have my wiring correct.

 

Ttt

 

Eddie,

The 12 volts is switched voltage, the ground is to the cluster or where ever you find a good one.

In your other post I told you to make sure to zero the tach. You should do this by running 12 volts to it from a source in the engine compartment. You should run a ground to the engine. Why. . . . You'll see. . .

Ok go to your other post and you’ll see what I mean by zero it out. Anytime you remove the needle from the tach you must zero it!

The reason I’ve told you to do this in the engine compartment area is unless you have a way to generate the square signal to the tach you are going to test the thing before installing it.

To test the tach and after you zero it out, run a wire from the “Tach” connector on the distributor to the back of the tach. (The lower connector). With 12 volts applied you should rest at zero, when you apply the signal you should be working. Now if you have a Dwell meter this would be a great time to hook it up to the car and verify the accuracy of the tach before installing it. If the tach is not reading correctly there is an adjustable potentiometer on the board you can use to tweak the reading.

Once you dial it in you are ready to install in the dash.

Eddie, you know how to get me so if you have a problem just drop me an email.

Just another note to put with this. Today we had an interesting thing happen. The shop calibrated a tach for a customer and he was shocked that it was reading 2K when he picked it up! This is perfectly fine! The tach will show the last reading when the power is cut off from it.


Willcox Inc.

 

I just finished zeroing the tach. Easy enough to do with some help from someone who knows how to do it. Thanks for sharing.

 

Make sure you test it before you put it in the car. It's easy to do and time well spent. The tach is hard to get out on your car and doing it now would be a bonus!

Willcox Inc.

 

Its tested and working. Now I am going to have to change the output of the LS PCM pulses to make the tach read correctly.