What wire makes the tach work? 1994 OBS Z-71

[Z-Rod]

I am using the factory tach. There is a white wire coming from the new computer that is the tach signal. The 680 ohm resistor is needed to make the PCM's signal work with the OBS tach. Without the resistor, my tach never moved. All of my gauges work perfect now, next is the cruise connections. I have the diagram, I just need to run the wires from under the dash to the PCM pigtail, right after I get that pigtail from the salvage yard. After that, I will finish the 4wd wiring. I need to send the PCM a signal when I am in 4wd low so it will change the shift strategy.

So far I have not encountered any surprises from the swap that were not caused by me... I think I hooked up my fuel filter/regulator bassakwards... oh well.

Z-Rod Out

[BlownChevy06]

hey can you explain how do we wire this 680 ohm resistor to the PCM tach signal wire and excicting white wire...? do i "T" it in between both wires with +12v switch?

[haveTBIwantLS2]

GOod job on fixing the prob.
I thought I was gonna need to do this since my truck is a 91, but the tach came alive when I fired my rig up. weird