Can anyone tell me if there is a wire from the coil neg going back to the ECU on an EB, and which pin (if any) it goes to. Is it 56 (PIP)? Thanks

theres no wire back to the ecu, what are you trying to acheive?
there is a tacho feed on the diag connector.

I was checking the ignition wiring diagram in my workshop manual and it showed a wire (pink/blue) going from the Engine Control Module to the coil. Mine works fine without it, but as this is my first attempt at a bare bones wiring job (speedway car), I was just wondering if there was anything in it.

is it a 6 or v8?
the pink/blue is a tacho feed, on the 6's it goes from the coil - through a resistor to the diag connector. all it does is give a tacho feed, and is not operationally required.
All the ignition control is done by the TFI via pip and spout signals.
on the 8's the pink blue goes from the tfi back to the ecu as an ignition monitor.

Its an I6 4.0 with the log manifold (not allowed to run the BBM). Thanks for your help - looks like my wiring is OK.