Hella Transflash II Relay

[Dazco]

Im currently putting the dash back in my van and im having a problem with a fuse blowing.
It all seams to be related to a Hella Transflash II relay, part no 4JA 004 663-00.
Ive taken the relay apart and found that prior to me removing the screen some water has leaked in and managed to get into the relay , corroding part of the board inside and is now shorting.
Ive done a search on various sites and google and from what ive seen its something to do with Towing and checking the lights are working (may be wrong)
can anyone else shed any light on the matter and where i might be able to get a replacement
If it helps i can post a couple of pics later. thanks for any forthcoming help.
Daz

[Hacksawbob]

Sounds like it may be the turn indicator confirmation. when you plug in a trailer you are supposed to have some sort of confirmation that it is working either visible or a beep.

[Dazco]

its wired to a bulb on the dash that flashes .been to a few caravan places today and noones ever seen one of these, bugger .
they sugested i bought as newer unit that beeps but connections are different and i dont want to start messing with the wiring.

[Dazco]

A few pics. how would i go about testing this relay? ive got a multimeter which i can check continmuity , voltage and Amps etc.