Brake lights
#1
#4
Is the high-mount light in the middle working? If not, your brake light switch on the pedal could have failed. Otherwise I'd think that the problem would be in the wiring harness on the passenger side (of a 240). I've noticed that the 240's tail light wiring runs up the driver side of the car, then goes across the rear to the right.
#6
#7
there are wiring harnesses throughout the car.
240 wagons, a common failure point is the wire bundle in the tailgate hinges.
the bulb out sensor is not a relay per say. further, its failure modes usually involve false bulb-out indications, NOT actual lighting circuit failure.
looks like the brake light circuit is pretty simple. power from battery to positive terminal (on left fender under hood) to fuse 7 to brake switch. from the brake switch, it goes to the bulb-out-sensor, and from the sensor, separate wires run to each of the 3 brake lights.
240 wagons, a common failure point is the wire bundle in the tailgate hinges.
the bulb out sensor is not a relay per say. further, its failure modes usually involve false bulb-out indications, NOT actual lighting circuit failure.
looks like the brake light circuit is pretty simple. power from battery to positive terminal (on left fender under hood) to fuse 7 to brake switch. from the brake switch, it goes to the bulb-out-sensor, and from the sensor, separate wires run to each of the 3 brake lights.
#8
#9
the 7/9's use essentially the same bulb-out sensor module as the 240's... they aren't all directly interchangable due to different pinouts and such.
the sensor is a bunch of counter-wound coils, like the left lamp might be wound clockwise while the right one is counterclockwise, these are all wound around a magnetic reed switch.... if the current in the left and right circuit are the same, then the magnetic fields cancel, so the reed stays open. the reed switch is wired to the bulb-out light on the dashboard.
if I was faced with a dead bulb-out sensor, I'd quite likely hack it open, gut it, and replace all the coils with jumper wires.
the sensor is a bunch of counter-wound coils, like the left lamp might be wound clockwise while the right one is counterclockwise, these are all wound around a magnetic reed switch.... if the current in the left and right circuit are the same, then the magnetic fields cancel, so the reed stays open. the reed switch is wired to the bulb-out light on the dashboard.
if I was faced with a dead bulb-out sensor, I'd quite likely hack it open, gut it, and replace all the coils with jumper wires.
#10
before sweating the bulb-out thing, however, some basic testing is in order.
get a volt meter, set it for DC Volts. black lead on a handy ground, and verify that both sides of fuse 7 are 'hot' (+12V) even if the car is switched off. to the right of the fuse panel are 3 columns of spadelugs. the right most of these 3 goes to the left side of the fuse (and is power input), while the middle and left spades go to the right side fuse clips, and are 'output'. fuse 7 should have a green-red wire on the middle or left spade. the input is the red wire to fuse 6 (fuses 6-10 are wired together).
that green-red wire goes directly to the brake switch at the brake pedal arm. pin 1 of thise switch should always be hot, pin 2 should be hot when you depress the pedal. pin 2 has a blue-red wire that goes to pin 9 of the bulb-out detector.
pin 5 of the bulb-out is a blue-black wire to the center brake light. pin 11 is a yellow wire to the left brakelight. pin 10 is a yellow-grey wire to the right brakelight.
get a volt meter, set it for DC Volts. black lead on a handy ground, and verify that both sides of fuse 7 are 'hot' (+12V) even if the car is switched off. to the right of the fuse panel are 3 columns of spadelugs. the right most of these 3 goes to the left side of the fuse (and is power input), while the middle and left spades go to the right side fuse clips, and are 'output'. fuse 7 should have a green-red wire on the middle or left spade. the input is the red wire to fuse 6 (fuses 6-10 are wired together).
that green-red wire goes directly to the brake switch at the brake pedal arm. pin 1 of thise switch should always be hot, pin 2 should be hot when you depress the pedal. pin 2 has a blue-red wire that goes to pin 9 of the bulb-out detector.
pin 5 of the bulb-out is a blue-black wire to the center brake light. pin 11 is a yellow wire to the left brakelight. pin 10 is a yellow-grey wire to the right brakelight.
#12
Thread
Thread Starter
Forum
Replies
Last Post
zinko
2001-2013 model year V70
5
02-11-2014 07:18 AM
Scott V
2001-2013 model year V70
0
07-21-2013 02:28 PM
chrystald423
Volvo V70
7
03-27-2010 08:05 AM