Reference: 1993 240 Sedan Brake Light Problem Fixed (new sensor worked)

This is just for reference as I just struggled through this problem and found many posts helpful but couldn't reply because they are older
threads. But I wanted to post the resolution for reference for someone else.
Problem: 1993 Volvo 240 Sedan with all lights working except brake lights (including third brake light in back window). Fuses ok (changed twice). Bulbs ok (tried many). Power through brake switch (the one way up above the switch for the cruise control). Had checked power to back flexible circuit board and power to the white plastic connectors was coming in only to parking, flashers, and fog lights. So it seemed the board was OK with the problem between the pedal switch and the connector in the back (sedan).
Pulled off the hard plastic near your knees (pull out plastic tabs and remove to star screws and then bring down and out). Reached up and pulled the black and red bulb failure sensor (~ 3 inches long and ~ 1.5 inces diameter) down from the clip that holds it. It comes apart (the black and red part but it was difficult.
As others posted, tested lead #54 by slipping in the voltage meter probe. Getting voltage in on #54 meant (I think) that power was coming in from the brake switch when the pedal was pressed. That is how I ruled out the brake pedal switch - it was easier to get to the senor then the switch. So then I kept the pedal down and checked the two out-going leads (#54L and #54R) and there was nothing on the meter.
I replaced the sensor with a $127 (late on a Saturday - no time for price checking) one from the volvo dealer and it all worked!
Hope this helps....
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thanks aplenty! my '90 245 has it's brake lights on all of the time. was this your problem also... why can't i just do a simple switch from the pedal to the brake lights... i've ignored the problem for 2 monhts... used to be a simple replacement on my previous 122 and '86 240s...
am i missing something?
thanks for any advice!
js
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snipped-for-privacy@gmail.com wrote:
: This is just for reference as I just struggled through this problem and
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AND Books wrote:

That sounds like the switch has failed.
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snipped-for-privacy@gmail.com wrote:

It's a reasonably common problem, the solder joints in the sensor crack, takes about 10 minutes with a soldering iron to repair them.
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I thought about soldering (as other posts had mentioned) but had run out of energy and patience for the day. But you are right - $100+ part versus $1.00 of solder...should have been a simple choice... :/
As a side note for the other post, my problem was that the brake lights would NOT go on. It was not the case that they stayed on all the time as I saw in other posts. AS James wrote, that does sound more like a switch that is stuck on.
Remember, at least on my car with cruise control, I think the switch for the brake lights is higher up and a little harder to see. The first one I see underneath is for the cruise control (it has a t-connector for the vacuum hose and then a small two-wire plastic connector).
When I first checked things, I checked voltage on both sides of that switch - which only meant power for the cruise was working. I really hadn't ruled out the brake light switch like I should have until I checked voltage coming in to the senor.
James Sweet wrote:

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