94 OBS 2004 LQ4 swap tach problem

[brharris27317]

I read the swap article and saw no mention of tach issues and maybe its just me. I am using a 2004 LQ4 which has the blue/green plugs instead of the red/blue. I have my tach hooked to GREEN PIN 10 which from my research is Engine RPM output to the white wire that I had traced back from the ignition coil from the original TBI setup and hooked it up and nothing. It looks like it moves some but that may be just wishful thinking or cam lope from the cam I am running in the LQ4. If at all possible I would like to get tach working and if this has happened to someone else please let me know how to fix it. Oil pressure and water temp, I used the old TBI sensors in the LQ4 block and those all work fine. I worked on the speedo wiring today and believe I got that fixed but battery was too low to crank and drive to see but I think its fixed.

[flattopwill]

I used an aftermarket tach with my setup and had no problems although I have red/blue connectors. It looks to me like you have the info you need but try this resource to see if it shows a detail you are missing. Tach wiring for 99+ Vortec/LS1

The PCM could be sending a 4cyl signal and you might need a converter box from msd for it to work. Just a guess.

[brharris27317]

Thanks, I will give that a try. I can get a Dakota Digital SGI-8 box to calibrate the signal for accuracy once I get the thing to move. I have a similar problem with my LT1 swap with my 91 Camaros tach reading twice what it should so I got that Dakota Digital box for that project. Just wasn't expecting the 2003+ PCM not to make my tach do anything.