Astra J, turns but will not start!

Gran Problema!

Driving home one night, turns corner and discovers traction control light (stability control) has come on (amber). Stops car. Engine management light comes on. Oh dear! Turn car off to try and reset. Will no longer start. Don't get me wrong, it tries! It cranks and turns pistons and shafts but will not actually fire up.

Called GreenFlag, came out and scanned the OBDII. Sanner claimed misfire on cylinder#2 but no other faults detected. So, off to euro car parts I went. Getting a new coil pack and 4x new spark plugs hoping that the problem would go away and that the non-starting was just a self protection mechanism. No such luck. Replaced the coil pack and the spark plugs and tried firing her up. Still no joy, now the worrying starts! Scanned again and cleared the fault code just in case. Still no luck. Now for the diagnostic approach, test everything and try and narrow the field.

Multimeters and OBD scanners out we set to it. All the pins on the coil pack harness read as expected, +3ishV on the spark plug pins plus a ground and +12V. Relays appear to be clicking except relay 3/4 (I can't quite remember which one) does not click on ignition and does not appear to be receiving a switched +12V in order to open the gate. Both relays are listed in the user's manual as "Ignition, fuel system".
I've sent the ECU away to be tested as that was our first thought (myself and the 70+ years worth of mechanics standing behind me) and appeared to be the most likely cause but no luck, the testers don't have a rig set up for my particular model of ECU and Delco refuse to give them the ECU schema to set one up (YAY FOR CAPITALISM AND PRIVATE COMPANIES).



In short, I've no idea from here in and neither of the time served mechs know what to do anymore. Have thought it might be immobiliser or possibly the key's transponder but unable to test as yet due to the ecu not being present in the engine bay.



Any ideas or help would be very useful as well as any guidance on possible ECU swap and the procedures involved in doing such a thing.



Thanks in advance guys, hope somebody else has suffered this issue and their car has lived to see the light of day again! Else... well **** it it'll have to be a new car!



Cheers!