Stack rev counter and GM ecu

[deadscoob]

Has anyone had issues trying to get a stack rev counter working with a GM ecu?

Am struggling to get mine to work and wondered if there were any weird things around configuring these with gm ecus that anyone knows of?

Thanks

[02PRUV]

Does it work at all or is it just not reading the correct RPM? I set the dash as a 4 cylinder to get an LS1 ECU to read the correct rpm on the dash.

[deadscoob]

Not working at all.

Demo mode works fine so motor is ok, but doesn't seem to be picking any feed up. Tried another brand tacho and it's ok, is pointing towards the stack being broken..

[LS7TANGO]

Hi,

Sorry away from workshop (as usual) but if I remember correctly you will need to install a pull up resistor in series - the GM ecu provides a 5v signal - to get the rev counter working. If you contact stack tech helpline the can confirm.

HTH, Simon

[deadscoob]

Yeah tried that, seems its a dodgy gauge.

[GTR-P]

You definitely need a pull-up resistor to make the GM ECU work with the Stack rev counter as the ECU produces a low voltage square wave output.
I experimented with various resistors to determine the largest value that would reliably work in 2010. I have experienced no problems since the installation of the pull resistor noted below.

The value I settled on was 22K Ohms 1/4W (The Stack manual recommends values between 470 and 4.7K Ohms)
Here were the results of various resistor values on the operation of Tach.

Resistor Value(Ohms) - Static Pull Up Voltage - Comment
33K - 4.5V - Intermittent Tach. operation
22K - 5.7V - Reliable operation
14.7K - 6.8V - Reliable operation
3.6K - 10.5V - Reliable operation

I subsequently came across the GM E-Rod Crate engine installation document p/n 19244807. It suggests a starting point of 5K Ohms. This document also contains lots of additional useful recommendations and is worth reviewing.

Installation:
The Stack ES cable contains 3 Wires.
• Red = 12V IGN power that is common power from the switched IGN voltage
• Black = Tach Signal input
• Bare stranded = Ground
The Red wire became the very handy switched 12V power source for the pull up resistor. Just install the resistor between the Red wire and the Black Tach input signal wire.