Would it work with some sort of a resistor in series with the light? and a relay that would swap back and forth from the resistor to the sensor, using the light to power the relays coil. Of course this all depends on how the sensor works. Or I could be up in the night and way off.Guys I am guessing here but try this on. The ecm will only go into limp mode on its orders from itself. And it will only do that as far as i know from info from some sensors like the temp sensor maybe oil pressure sensor.