1989 Volvo 244 DL
Still kicking at 340k miles!

Summary:
All three brake lights do not work in all ignition positions
All other exterior lights do work (Except for the right reverse light, will explain more later)
Checked voltage potential at fuse #7 (Looks good, when brake pedal is depressed)
There is no voltage potential at the left brake light socket
There is no voltage potential at the wire interface to the left exterior light circuit board

From my understanding in the Chilton's repair manual, the wiring to the brake lights run from the ignition (always hot post), to the brake light switch (pedal actuated), to the fuse box (8 amp fuse on #7), to the bulb failure relay (under the dash), to the brake light fixture, and then to ground.

I am wondering whether replacing the bulb failure relay will fix my problem. Does anyone have any experience with this issue? Also, is there anyway to test the relay before I spend 50-80 dollars on a new one?

I also noticed that when I removed the bulb failure relay, all of the exterior lights shut off except for the fog lights, and the left reverse light. Some time last year, all lights were functioning properly, except for the right reverse light, which was not functioning while the car was in reverse gear. Then for no reason at all, I noticed that all lights were working properly. Just recently (my friend alerted me several days ago) that my brake lights were not working.

If anyone can help me diagnose the problem I would GREATLY appreciate it! I'm currently in college without a whole lot of money to spare so I am trying to find a cheap way to diagnose and fix this problem without hiring someone obviously...

Thanks for your help!

 

You can bypass the bulb failure warning sensor (BFWS). Pin 9 comes from the brake pedal switch. The juice goes out of pins 10 & 11 of the BFWS. Pin 10 goes to one side brake light, pin 11 goes to the other side. Connect a jumper wire from pin 9 to pin 10 (or 11). Step on the brake and see if you gots a brake light.

The BFWS is a fat red relay right behind the left vent next to the instrument cluster. If you remove the cluster it's sitting right there looking at you. Or you could come up from the bottom, removing the kick panel above the driver's legs.

 

So it it correct that power for the rear brake lights comes into the bulb failure warning sensor (bfws) on pin 9 and goes to the rear circuits on pins 10 (L) and 11 (R)? Also the running lights on 12 & 13?

Left rear light and brake light work. Right do not.

Can't figure it out. Have checked grounds. Reverse and turn lights work both sides.

Any ideas.