Mk II Focus TDCi Ghia

When the vehical is not doing more than 5 MPH and i touch and release the brake pedal the tailgate mechanism operate to open the tailgate.

I have removed and checked the button from the tailgate, there is no sign of water ingress and the problem persists with the button removed so that rules that out.

All the loom in the bits of the tailgate I removed the plastics from look OK.

Google searches turned up a reference to a recall but the dealer says there is no recall outstanding for my car.

Anyone able to shed any light on this, I'm booked in tomorrow and don't fancy a large bill for something i can fix myself "with a little help from my friends!"