Assuming it's not the obvious like a blown bulb, then, If it's anything like the scenic 3 (which it normally is) there is 1 heavy duty permanent live cable ran to each of the rear clusters (along with a heavy duty ground). Then a little signal wire to activate the brake light and another signal for the indicator. The first test for you is, "does your indicator work" this will prove your heavy duty cabling. If that's ok then your looking at the signal cable which is a thin wire that runs from the body computer behind the glove box through a couple of connectors and ends up at the light. There are dedicated signal cables for the left, right and high Level lights.

 

IceReturns, many thanks for your reply. Previously I had replaced the bulb, and the checked the indicator (which works).

Do you (or anyone) know whether the fault is likely to be a loose/corroded connector, broken signal wire or body computer fault?
Many thanks,
Pete

 

I'm out at work at the moment so I'm limited in the info I can give, but for a fault like this I would start at the beginning (the connector on the light as it's really accessible) and work my way to the end the body computer. Assuming you have a multi meter I will try to give you some pointers later.

 

Ok, so starting with the 5 pin connector going into your light :-
Pin 1 = Indicator control signal (Im assuming it goes 12V +ive when needed)
Pin 2 = Brake control (Im assuming it goes 12V +ive when needed)
Pin 3 = Not used
Pin 4 = Permanent +ive
Pin 5 = Gnd

I originally thought there may have been some intermediary connector for you to check, but apparently those signal wires then run directly to the body computer.

Body computer BCM/UCH
Looking at connector 'E' it is a black connector with 2 rows of 20 pins (40 pin connector)
For Comparison sake your rear right brake is controlled by Pin 39 but your Rear Left Brake is controlled by Pin 40 (Im assuming it goes 12V +ive when needed)

Body computer is situated behind the glove box. Also note that the On/Off peg for your glove box light is removable, once you have removed the light, remove the peg, when refitting the light, put it in position and then try to slide the peg in to place.

 

Thank you, that' very usefuI information. I think I'll be having some fun this weekend with a multimeter and checking the wires...

 

No problem