tach help??
Should be pin #35 White wire (Engine Speed).
There is another pin #35, which is LT GRN.
Not sure which row of pins (blue conn/red conn) on the ECM.
Also, you may need a 'pull-up' ckt to create a useful signal for the tach.
Thanks to "FastKat" for the diagram, & the POT idea.
The WHITE WIRE-pin 10, noted in the diagram, is from a different year.
As an alternative, & more exact circuit, you could wire a POT (variable resistor) in, instead of the fixed value 680 ohm resistor. Turn the POT until you get a good tach signal. Then, remove the POT & measure across it, to find the exact resistance threshold which operates the tach. Replace the POT with that resistance value.
There is another pin #35, which is LT GRN.
Not sure which row of pins (blue conn/red conn) on the ECM.
Also, you may need a 'pull-up' ckt to create a useful signal for the tach.
Thanks to "FastKat" for the diagram, & the POT idea.
The WHITE WIRE-pin 10, noted in the diagram, is from a different year.
As an alternative, & more exact circuit, you could wire a POT (variable resistor) in, instead of the fixed value 680 ohm resistor. Turn the POT until you get a good tach signal. Then, remove the POT & measure across it, to find the exact resistance threshold which operates the tach. Replace the POT with that resistance value.
Last edited by gMAG; Dec 11, 2012 at 03:44 PM. Reason: blue conn/red conn
