Does anyone know for sure what this wire is on a 52 plate vectra C 2.2 petrol, it's the GMPT-E16 engine management unit.
There are two multi plugs on the top of the ECU and next to them is a single lead, goes to a screw or bolt that apears to attach to the case.
Looks like an earth to me but i can't find any wiring diagrams that cover the ECU.
