My 240 wagon top tailights are out and I can't figure out why. I replaced a bad brake light bulb and when I finished that, my top taillights won't work any longer and the bulb sensor is on. Luckily the bottom ones are still working or I couldn't drive it at night, but for the life of me I can't figure out what's wrong. Could I have loosened a wire in the bundle? I did go back and everything looks connected.

 

Make sure the Tabs that the wires plug into didn't crack/break.

Then check for power at the wires. The sockets might have a dirty connection as well.

 

Ok, all connections are correct and clean, bulbs are fine. I think this may be an electrical problem due to these other hints: When the back door is open, the stoplight on the window is OFF, and I can hear clicking in the gearshift area when I step on the brake when the lights are on. Sometimes the sensor light is off when I first start the car, but goes on again when I step on the brake, then it's on forever.

 

Maybe something is shorting out from a bad tailgate wiring harness.

 

Hey I'm having the same problem! I think it may have something to do with the circuit boards on the tail lights check and see if all the cooper is still on and that the plastic isnt disrupted!

 

His car is a wagon and doesn't have circuit boards.

 

Ok, here's the deal. The top lights on the back of the wagon are Fog Lights that only come on when you push a switch on the dash. I've had the car since it was new and never realized I had fog lights. Anyway, the bulb sensor light still is on so I took it in to my favorite Volvo mechanic, Swedish Speed and he told me that when you replace a bulb, replace the companion bulb on the other side and make sure the manufacturers are the same and they are of good quality. The sensor is detecting a break in the electrical system, thus turning on the bulb out sensor light when in fact there is no bulb out.

 

Check the sensor - a gizmo under the dash (driver’s side) the monitors all the bulbs. Had some flaky problems with tail lights and brake lights. Dash indicator stayed on no matter what I changed. Then I changed the bulb sensor. Not expensive used but a royal pain when it goes out. I keep a spare in the car. Volvo uses the Bosch electrics on the 240s, inclujding the 1930’s style fuses. I clean the contacts with an emory board and change the fuses whether they look good or not. That ends many electrical problems. Some guy on ebay sells Bosch fuses for the Mercedes 123 chassis that are made of better metal that does not react with the fuse box contacts. The standard fuses corrode and go intermittent. Start with the fuses which are cheap before spending more money.