Posted by Michael Whitworth on March 24, 2006, 8:56 pm, in reply to "Re: Polo "
Hi Mike,
Without an engine code i am talking in general here but with this system I would expect dissy to be a hall effect with three wires at the multi-plug marked + 0 -
The plus will be 12v from relay (or ign switch) The minus will be an earth The zero is the signal and will have anything upwards of 5v on it depending on system.
The job of the hall effect is to pulse the signal wire to ground giving a square (digital) waveform on a scope. The ECU uses this signal to determine when to make a spark and inj pulse.
After processing this signal the ECU outputs a Squarewave signal to the Amplifier which inturn will switch the coil primary.
The coil/amp assembly has a three pin multi plug of which two are live and earth and the third carries the squarewave signal from the ECU to the module. If you crank engine and monitor signal pin on coil/amp assembly multi plug, you should see a squarewave or maybe pick up a dwell or duty cycle reading on a multimeter.
If there is a signal present and you have a good live and earth to this module under cranking then it is most likely to be this unit at fault.