That's how the coil-on-plug set up works, and as with a lot of cars, the switch is the negative wire in the ECU.
The interesting part you'll see is that the plugs aren't electrically connected to anything. The coil acts as a transformer, and when the ECU grounds the primary (top) coil, it'll become a little electro-magnet.
When the power is switched off again, the magnetism collapses, and the magnetic flux shoots through the secondary coiland induces a much higher voltage, as in 20-40,000 volts.
The problems you get are the individual coils (top and bottom, primary and secondary) breaking up so they act like less loops, or the real bad one, the secondary coil ends up short circuiting to the primary coil and sending 40k Volts into the ECU.
Older single coil systems have one massive coil instead which has to fire for every cylinder-
You can see all the loops of wire, and they are the ones that can start to short circuit when the coil breaks down.
i remember doing that at college.
nice to have a decent diagram to visualise it better (Y)
|« Previous Thread | Next Thread »|