Car=1993 240 wagon
Problem=no brake lights

I have voltage going in and back out of the brake pedal switch when it is activated as should be but no voltage to either side of the brake lights. Ran a temporary wire from the switch output directly to either brake light and they work fine.

I cannot follow the wire from the switch as it goes into a jumbo bundle of twisted wiring. There must be a split somewhere up front before sending two (left & right) wires to the back of the vehicle? Does the wire from the switch go to a junction box or any other relay or component first?

Thanks,
Arne

 

the wire goes from the switch to the 'bulb out detector' and splits inside that, two wires come out of that, go through the fuse panel, and back to the brake lights.

 

Thanks Pierce,

2 questions-where is the bulb out detector located and which fuse # do the wires go to from that detector?
Thanks so much

 

under the drivers knee bolster, normally a red and black cylinder. More likely then not you will find that its charred or melted at the brake lights. as this is a common issue, I bypassed mine completely, the only issue is that by doing so you forgot the bulb out dummy light.

they fuse at #12 the detector itself is not fused as its simply a passthrough device

 

Bulb Failure Sensor is this cylindrical 'relay' module under the dash, almost the size of a beer can. oops, the only fuse is up front of the brake light switch, its fuse 7.

from brake light switch, blue-red wire goes to Bulb Failure Sensor (BFS) pin 9. BFS pin 10 is yellow-grey to the left brake light. pin 11 is yellow, to the right brake light, and pin 5 is brown-black to the center light.

 

I don't have voltage at the blue-red wire in the BFS pin 9 when I depress the brake pedal. But I have voltage at the brake pedal switch out put.

Also none of the other wire colors you reference above apply to this car. Did they change colors in different years? And further, the wire at the left brake bulb is purple but there is no purple wire at the BFS or the fuse box #7.

Any ideas? I need more help.

 

the wire colors I listed were from the 1993 (late) greenbook. the late 1993's have a 4 fuse holder right on the positive terminal of the battery.

in this late 93 greenbook, it shows a red wire directly from the battery fuse "Y" to fuses 7-8-9-10, and a green-red wire comes from fuse 7 to the brake light switch.

in the 1992 greenbook, it shows a brown wire from the positive terminal to fuses 7-8-9-10 (actually plugged into the right-most terminal on fuse 10), then green-red from fuse 7 (middle terminal) to brake light switch pin 1, blue-red from brake light switch pin 2 to BFS pin 9, ohter colors exactly the same.

no purple wires shown anywheres I can see. yellow or yellow-grey is whats shown at the tail lights, and at the bulb-failure sensor.

 

OK an update. I have brake lights now but I bypassed the bulb failure sensor. I don't know if that unit is bad or not. The wire colors I spoke of are sent to the back of the car via a 24 pin connector by the drivers left foot. whit/purple for right, purple for left and brn/blk for upper center brake. So the individual brake wires are NOT sent directly from the bulb failure sensor. Blu/red to the sensor carries the hot lead from the brake switch but I don't know which wire(s) then feed the brakes but they don't match the colors you listed at all. I have ordered a new sensor.

 

the pin numbers at the bulb failure sensor should match what I said...

 

Yes Pierce,
Those wire colors do match up after all.
Can you tell me if the right rear parking light goes thru the bulb failure sensor and if so which wire feeds the light?

Also the same question for the license plate lights. I think the BFS is out and I have one on order but it is slow in arriving and meantime I may try to bypass the above mentioned lights if in fact they travel thru the BFS too.

Thanks

 

see volvo 240 Mods and Fixes

there's like 3-4 versions of the bulb failure sensor as detailedon those pages. you can cut it open, gut it, and solder up a bunch of jumpers between the pins as an alternative. for your 93, see http://www.davebarton.com/pdf/bulbfailure86-93.pdf

 

The wiring problems to the back of the car were so many, it's difficult to pin point the culprits to each problem. I started out with no brake lights but pretty soon I had all kinds of problems with lights at the rear.

First-the bulb failure sensor failed and was the cause of at least a couple brake lights as well as the right tail light.

Also the rear door hinges had severed several wires on both sides of the door severed (both hinges) I had to pull the rear door and splice in new wire-quite difficult. The wire thru the hinges is definitely a weak point.

Thanks for the help. Wish I would have had that PDF of the bulb failure sensor from the get go.