Polo wipers operate continuously, will not stop

[nealepb]

My wife's 2000, W Reg, Polo 1.4 Petrol 5-door hatch has developed a mind of its own.

As soon as the ingition is turned on, both front and rear wipers operate.

I have tried operating the switch in all positions (a bit obvious), but it makes no difference.

Removing Fuse No50 stops the front wiper (as expected)
Removing Fuse No 6 stops the rear wiper (as expected)
Putting the fuses back in causes the wipers to operate again (as expected)

Opening the Hatchback stops both wipers, just before it is fully open (the exact position varies a bit). Shutting it causes them to start again.

Disconnecting the courtesy light inside the Boot area (suggested on a different discussion forum) cures the problem and th ewipers operate as normal, under command of the switches on the stalk.

Does anyone have any idea what the cause is, or how to fix it permanently?

[sonic]

option 1:
check the relays for the wiper circuit.

option 2:
disconnect front n rear wiper motors
remove fuse 50 and 6
connect test light to fuse 50 terminal 1st.
ignition on
if the test light lights, then u have a short circuit
repeat same test on fuse 6 terminal

luggage light and wiper motor SHare same earth on this vehicle.
check earth connection near the left hand tail light
perform option 2 tests on fusses 11 and 10

[nealepb]

Many thanks for the hints and tips, Sonic.

I could not see any obvious problems with earths in the tailgate, or near the left hand tail light cluster.

Before disconnecting the wiper motors to follow your Option 2, I thought I would just take a look at the wiring loom as it goes between the body and the tailgate on the left hand side. There I found a Red and Black wire where the insulation had been worn through and I could just see the conductor inside. I taped that up and put it all back together - the fault SEEMS to have gone.

As I don't have a wiring diagram, I have no idea what the Red and Black wire does, so I cannot judge how likely that is to have been the cause of the problem, but bare wires in confined metal spaces cannot be a good thing, so fingers crossed.