Gents,
I bought an OBD Scanner - ELM 327 device... talks via blu tooth to your Android fone and gives you a constant readout of the entire electrical system of your vehicle....
EBay for about £$ 10. you will need to download an App called TORQUE for about £$3 too, and it really does work.

The device give rpm, fuel economy, a running commentary of all ECU functions and systems and all sensors etc... if it's got wires poking out and some kind of sensor, this thing should find the fault and why...

GB