2006 XC70 Position Light Failure - bulbs, contacts OK

psimmo · Post by **psimmo** » 07 Jan 2015, 12:29

Both rear offside sidelights (position lights) flash when I turn the car on, then immediately go off.
Bulbs checked and changed, fuse checked and changed. Earth and power supply must be OK to make them flash. All other position lights working fine. All other lights working fine, including the lights in the rear offside cluster (except for the little LEDs which aren't working also, and don't flash either)
Suspect a problem with the rear fuse board, or the trailer unit (towbar (Volvo fitted)) attached to the circuit, or a kink in the wiring going across the car from the fuseboard to the lights.....but just guessing. Anyone met this problem before? (main agents hadn't)

draser · Post by **draser** » 08 Jan 2015, 11:55

If they worked after the dealer installed option and now quit, then I'd find what controlls them with wiring diagram. Electrically they seem okay from your description. You may even try a hard reset with disconnectig the battery. If they never worked after dealer option then I'd take it back.

psimmo · Post by **psimmo** » 08 Jan 2015, 12:28

Problem now sorted. LEDs in the cluster had damp on the circuit board and the protective circuitry was spotting a short caused by this and switching the circuit off. The flash was this process in action. Clever designers eh!
It appears post 2005 XC 70s (and others) were installed with this protective circuitry.
Car now fixed with the extra precaution of loads of silicon to prevent more water ingress. LEDs had it though and expensive to replace!