volvo 940 gl

alirat · Post by **alirat** » 24 Feb 2005, 16:18

My brake lights are not working , I replaced the bulbs but have no power to the brake lights , I checked the brake switch and I have constant power into the switch and power coming out when activated but I still have no power in the rear . the wiring diagram shows a light fail sensor for the power coming out of the brake switch but I cannot find that box . Any help is appreciated . Paul

LaRy · Post by **LaRy** » 27 Feb 2005, 06:23

That light fault sensor is a relay and is placed together with the other relays behind the ash tray. I agree that according to the wiring diagram, it is hard to see where it is placed. It is big, round and locking like a electrolythe capacitor. What about the high placed brake light in the middle, does that one work?
This relay is just comparing the current flow to both lights and has probably just some coils inside. It would be very supricing if it is broken, not letting voltage through, and same at both sides. If you want to test it, incoming pin for brake is connected to 54, outgoing is connected to 54L, 54R and 54M (middle light). Check that you have connection between incoming and outgoing pins.