I'm working on a friends '91 740 wagon. He's got no brake lights. All 3 are out, every other light works, and the "bulb out" light on the dash is not on. The fuse is good, there is power to the brake light switch under the dash, and power through it when the pedal is depressed, but there is no power at the back of the car in the wire for the brake lights.

The fuse location tag indicates that the #4 fuse is for the brake light, and "shift lock". Should we be checking for a shift lock switch? I don't see how the two are related, but if somebody says they are I'll take your word for it.

I did a search, but after reading about a dozen threads about bad bulbs and loose sockets, my brain melted. Neither of these is my problem.

Short of tearing the entire car apart to follow one wire, is there anything I should check? Any thoughts appreciated.

 

Hmmm, weird! I'd change (swap) that fuse, just because. Then, short of tracing that wire from the switch and on, I don't know. Strange that the warning light is not on-usually those things are hyper sensitive. I'd also recheck the work done so far-sometimes things get missed, and usually in a mysterious situation like this, it may be the answer.... keep posting...

 

I have the identical problem on a 1992 740 .power through the switch and fuse and no volts at the lights (all three). Did you have any success? Is there a relay or something else in the path? does the wiring go back up through the headlight switch or some other weird path?

any hints will be greatly appreciated

Phil

 

Well now, I scratched around the 740 for an evening and found 12V at the fuse,through the brake switch and then the wires disappear into a maze of organized spaghetti and loses the 12V by the time it gets to the taillights.
I searched every source of Volvo scripture I could find and came up with a wiring diagram that showed the brake light wire going through a "bulb condition sensor,bulb integrity sensor" and a few other names indicative of that function. Why that would stop 12V from getting to the lights ,I don't know but I found another post mentioning the same story .I replaced the sensor $ 64.00 ( partsgeek.com) and voila I have brake lights again .

Phil

 

I've been out of town for work and just got back around to working on this problem. I was in a junkyard today and found the bulb failure relay was missing in all but one car. I grabbed the one I found, swapped it, and I got brake lights.

 

I'm glad I found this thread because I was having the exact same brake light issue on my '92 740 wagon. I checked all of the usual suspect areas, but still no brake lights. Then I took the advice of the other two posters here and ordered up a bulb failure relay ($55 at eeuroparts.com) and now my brake lights are back in business.

Justin

 

I have the same situation with my 2001 S60... Can anyone tell me where the brake light sensor is usually found ? thanks

 

I had this problem a few months ago. All of my brake lights simply weren't working. Its an expensive fix($55-$120), unless you go to the junk yard... To test that it is the relay, check out this article. It fixed my problem. https://volvoforums.com/forum/volvo-240-740-940-12/240-brake-lights-19551/