Odd electronic issue

[thebadger]

Hey guys, I need some help as to what I can do.

My car is saying that the tailgate is open (it also switches on the boot light) but this only happens when I switch on the rear window/wing mirror demister on.

I've tried the usual UEM reset procedure, but to no effect.

Has anyone else had this issue, or advice on what to try to remedy it?

Thanks in advance!

[Harvey]

I would guess the harness has a broken wire or the insulation is poor cracked near the tailgate hinge and some water is in there,I lost locking on tailgate ,rear doors.

This photo was what mine harness was like,just fitted a new one.

[mikealder]

Get the tailgate hinge point wiring inspected ASAP, the last phase 2 V70 I went to look at managed to burn out loads of the wiring in the rear of the car and damaged one of the outputs from the CEM, doesn't take too long to repair simply replacing the damaged sections of wire with new lengths soldered or spliced in, to get at both ends of the wiring take the D pillar trim off the car and the upper inner tailgate trim panel - Mike

[LeeT5]

Hey guys, I need some help as to what I can do.

My car is saying that the tailgate is open (it also switches on the boot light) but this only happens when I switch on the rear window/wing mirror demister on.

I've tried the usual UEM reset procedure, but to no effect.

Has anyone else had this issue, or advice on what to try to remedy it?

Thanks in advance!

That's because you have an Earth fault. Resetting the UEM will do nothing. As Harvey has shown, the earth fault is most likely to be the wiring harness for the tailgate.