Stand Alone Harness - White - Tachometer

Tachometer

1.   White wire

ECU controlled tachometer output signal

A.     Supplies Engine speed (RPM) Signal to tachometer

B.     Most LSx engine computers will output a 4 cylinder signal unless altered in the program

C.     Early LSx engine computers (Blue/Red or Blue/Green style) output a 0-12v square wave which is compatible with most tachometers.

D.    Later style LSx engine computers (E40, E38, E67, etc) output a 0-5v signal that usually requires a pull-up resistor to work with common aftermarket tachometers. This resistor is pre-installed in the wiring harness from CPW and should not require anything extra be done on your end.

E.     Occasionally, the 03-07 Blue/Green style ECU will need a pull-up resistor installed for the tach to work. Some operating systems have adjustments in the tach settings, so it is not needed, but sometimes certain combinations of computer, program, and tachometer just don’t work without the resistor. See below for how to install when needed.