Kestrel
Active member
- Joined
- Sep 4, 2010
- Location
- Albuquerque, NM
Some of it is very simple, other parts are more complicated.
The warning lights, indicators, and backlight are all just piped out to the back connector, so making them work is just a case of connecting the correct wires in the car. I designed a circuit board that makes it plug-and-play:
We modified the thermostat housing to accept a CBR1000RR coolant temperature sensor. That is wired straight to the cluster to show coolant temp:
The speedo and tach are a bit more convoluted. The tach expects 2 pulses per engine revolution to show the correct RPM. The megasquirt can only output either 1.5 or 3 pulses per revolution with this engine. The speedometer shows 10KPH per 100Hz, which translates in to a ~70.4 tooth tone ring on the rear diff. Obviously neither of these things are even close to lining up.
I was hoping to hack the firmware on the cluster to re-calibrate it, but that proved to be beyond my patience. Instead we opted to put a frequency multiplier/divider in line with both signals. It's just a small circuit board with a microcontroller that lives inside the instrument cluster and correctly re-scales the input signals.
Many thanks! I suspect most ECUs expect a simple square wave for the speedo? Probably fairly simple to grab ye olde function generator and work out the calibration. Regardless, very cool idea and execution.