Just as it states, how can i check the signals at the ECU from the CAS, and to the leading coil pack?

 

I can only tell ya about the S4 n/a, although the S5's and turbos should be similar. You'll need to find the pinout and usual voltage readings in the FSM, for the S4's it's in section 4A, pages 30 to 32...

There will be 4 CAS inputs total, IIRC they are all around 1 or 2 volts (it's really just an EMF signal from the magnets passing through the CAS coils' fields, & it ain't much)

Much the same for the ignitor triggering outputs from the ECU, low voltage IIRC...

All voltages will be read with the negative meter lead on ground. Studs sticking up around the ECU are good for this...

 

So the readings can be taken with a simple DMM right? Ive got one, im not too familiar with electrics...

I just set it to the lowest volt measurement on there cause im only measuring low signals? I only have the haynes manual and i will check that now for electic schematics, if not will you post a link to a PDF factory manual?