[sambo]

Sideshow, it's one of your looms. Well, the ECU/engine part is anyway. Not your fault though, I wired the rest of the system.

Yep starter relay is the one that's "tripping". I've disconnected the immobiliser for now.

The car starts perfectly. It's when turning off the ignition, going from ACC to OFF that it blips the starter (via the starter relay) for a fraction of a second. If I disconnect the ACC wire from ignition barrel to main fuse box, the problem goes away.

So how do I find bad earths using a multimeter? I tried measuring resistance but the readings were all over the place and inconsistent even when testing the same spot.