So I have a 93 rx7 which previously had an Electromotive Tec3R. Since I have replaced it with a Microtech LT-16c. The only issue I am having is that the tach does not read but it does display on the laptop program. The tach worked fine with the Tec3R. I connected the Yellow w/ blue tracer (car side) to the Microtechs Blue W/ white tracer. I have continuity between the two wires. I checked with a test-light and the connection showed voltage. So I cut the connection to see where it was coming from, and found that with the key on the car side Y/blue is showing 12v when I connect the two wires and check with a test-light you can see it flicker when the engine is cranked but the tach does not move. Is it possible that there is a way to turn on tach output in the programming, and it's possible that it's turned off?
Other than that the ecu is working great the green and yellow light are light the red is not. The car starts and runs no problem just the tach issue

First startup on the new setup...

 

You need to trace that wire and see if it's getting to the tach. When you changed out your wiring it's possible that connection was broken. If all else fails you could tap into that yellow/blue stripe wire and run it to the appropriate input to the instrument cluster.

Dale

 

I only cut the wire from the tec3r and replaced it with the Microtechs. I can see what your saying, but if it came disconnected how would it have voltage?

 

That wire is fed from the trailing coil, that produces the tach output. Obviously it's getting to the ECU it just isn't getting to the tach.

Find out if the wire going into the back of the tach is getting a signal. If not, wire it up, if it is, you may have just had your tach die, not an uncommon problem.

Dale

 

what I',m saying is the yellow wire with blue stripe has 12 volts with the key on is that normal ?(disconnected from the microtech) l I do not have the factory harness in the car. should that wire have switched 12 volts coming from the tach?

 

Fixed it, I wound up just going to the back of the cluster and she's back in action. And btw there should be no voltage on the car side Y/L wire.