Ask The Editors: Gas to Electric Conversion Speedo Issues
Going electric causing issues with the instrument cluster.
The problem I have, as I no longer have an engine flywheel, there is no pickup coil sending an AC signal to the ECU to let it know engine rotation speed.
With no AC signal, the digital speedo remains at zero regardless of vehicle speed.
I have overcome this by using an AC transformer to mimic the AC signal so the ECU thinks the engine is running at 4800 RPM all the time and the speedo now works fine again.
This has thrown up another problem, though, because because the AWD will not engage above 3100 RPM.
I have been trying to find a way of fooling the ECU into thinking the engine is running between 2000 and 3000 RPM but haven’t found a solution yet.
If I could just get the speedo to work without having to mimic the AC signal or the AWD to engage above 3100rpm, then all would work okay.
Does anyone have an idea of how to overcome these issues?
That is a very interesting dilemma. Modern electric vehicles overcome similar snafus by integrating a sensor that sends electric pulses to the ECU from the electric motor shaft (rather than the flywheel) for an accurate RPM reading. In your situation, your machine relies upon the precision of electronic components as can be expected only from an internal combustion engine but are now expected to function off an entirely different means of propulsion.
We have a couple solutions for you but would probably consider them temporary fixes. The real solution would be to obtain an OEM EV instrument cluster sensor and to adapt that to provide your machine’s ECU with accurate electric motor output information.
In the mean time, you could run a jumper to bypass the speedometer and AWD RPM cutoff circuit altogether. If memory serves, it is the brown/white wire behind the 6-prong harness. Your meter should show 12 volts here when AWD is engaged. Detach this wire, ground and electrical tape it then reattach the harness. This should allow you to once again engage AWD as you see fit.
The downside? Since they share a wire, you lose your speedometer again. We would grab a GPS speedometer with suction cup mount like this one here.
The last place you have control over is the AC transformer you installed that is putting out a signal equivalent to 4800 RPM. What is this installed to and how is it achieving that steady number? It sounds to us that although tricking the ECU isn’t possible on that end, getting this transformer to read off somewhere like the motor output shaft would solve all of your problems.
Again, these aren’t great solution, but should at least work until you can track down an OEM EV speedometer sensor, which, as full EV SxSs even from Polaris are arriving to dealers as we speak, shouldn’t be much longer.
