Need some help. I have a 7747 ecu and am trying to use a innovative LM2 wideband o2 controller on it. I got the TPS, and MAP signals to log and view fine, but cannot get the RPM output to read on the LM2. I have tried several places to get an RPM signal (coil, control module, injector). I would like to run it off of the TACH signal from the ecu. does anyone know which pin on the ecu runs a tach signal??

 

The tach signal is directly from the coil. It is the white wire that leads into the harness. On the coil connector it is paired with the heavy pink wire. This wire usually has a fast-on type connector about 6 - 8" from the coil.

RBob.

 

That was my worry this was the only tach signal. I have tried it and cannot get the lm2 to read off of it. When i view the output of this wire on an oscilloscope the wave form is very ugly, common from a coil output, very large voltage spike and lots of ringing. I was hoping for a 5v square wave or 12 volt signal from the ecu i could use. I guess the closest i can get to this is the injector signal???

 

You could use D4, EST from ECM to distributor. But it isn't something that I would do.

RBob.

 

Would you be worried about the LM2 ruining the signal?? elaborate if you would
thanks for the help