I have a pretty clean low mileage 1990 Volvo 240DL. When I bought it a week ago all three brake lights didn't work. At some point they started working for about a day and now they are out again.

Trouble shooting I have 12V power at both sides of the fuse. I bought a stop light switch to install but it looks nothing like the one on the car. The switch on the car has a vacuum hose connected and a small two wire fitting. I disconnected the wires from the factory switch and installed a jumper still no brake lights. I read there was a relay on some of these cars just not sure what one is for the brakes.

Anyways anybody have a link for a wiring diagram or thoughts on the problem?

I checked the light circuit boards and they look to be in good shape. I wouldn't expect all three to be out anyways.

 

It's probably the Bulb Failure Relay. At least that's what it'd be in a 740/940. I am not sure if the 240 have that but I think they do... It's a big round red job and causes what you describe--no brake lights at all...

The switch you describe is the Cruise Control Vacuum Dump Switch. The brake switch is further up.

 

Thanks for that information I will look a little farther up and check for another switch.

Edit:
Found the switch up above the steering column pulled off the wires and tested new switch no luck. I did see the red cylinder type electrical connection that will be next, looks easier to replace than the switch just more money.