Hi All - I've been fault-finding the electrics on my Zafira B Z16XE1. The engine would not crank, and I suspected Immobilizer at first. OP-COM showed CIM OK, but no communication with ECU. Checking UEC, I found no volts on F21. Tried bridging associated relay next to it, and things suddenly came to life. Swapped relays, but problem is still there, so must be something inside the UEC - corrosion maybe.

The problem is, I've no idea how to get the UEC apart. There are some torx screws in the top plate, but one of these is half hidden by the module cover, and I can't pull or lever this off. Does anybody know how to get the thing apart? It's like one of those mechanical puzzles you get.

I'm also trying to find a proper wiring diagram.