Hey all,

I have a Elite 1500 controlling a K24 in a 2002 NB Miata. Tacho previously worked with this exact ECU controlling the original VVT motor with the PnP harness adapter.

The dash works, fuel gauge, speedo (controlled with a DPO) works, ODO works, turn signals, bulb etc. Works and I have verified the following:

ECU Settings: Using Tacho function, 12V pull up, active state low, 4 pulse per cycle, needle sweep 8000 rpm

Continuity between DPO1 and Dash Pin 2K (even tried running a brand new wire direct from ECU to dash to test and no change).

Dash Pins 1F, 1C both have 12V.
Dash Pins 3J, 1N both have good grounds.

Dash Pin 2K shows ~6V when Tacho Output is giving a signal (like the initial sweep on power ON)

Dash Pin 3G has power when headlights are on.

Dash Pin 1P (start) and Dash Pin 3H (Instrument Lights Dimmer) are both unconnected. If this is the problem what signal would I need to provide these pins?

I replaced the cluster with another unit from ebay with no change either.

At a loss of what else I can test, appreciate any help

 

With key on/engine off, do you have about 12V on pin 2K?

 

Yep, around 12V on 2K with key on/engine off. When running it drops to around 6-7 with the 50% duty cycle frequency signal

 

If you change the output to be on/off and set it to on, does the voltage drop to 0 volts?

 

Sorry - just got back from Japan lol but going to check this again - when you say set the output to on i tried these:

I can set it to "on" by just output any specific frequency at 50% duty cycle with a 12V pull up (which is what the Haltech uses for its tach output signal)

• When I do the above the voltage is around 6V measured from 2K to one of the ground screws on the back of the cluster.

I can do also change it to be a simple "state on/off" output with the 12v pull up enabled.

• When I do this output set to OFF = 12V, ON = 0V