Well after 411K miles I finally had the brake light failure on my 89 740. Checked all of the normal areas and it came down to the warning light failure sensor/relay. So I pulled the big red relay and got out my green book to check the wiring. Pulled the cap off and tried the jumpers but it didn't fix it so I assumed the PC board had a failure. All other lights worked except the 3 brake lights. So I jumpered pin # 54 to 54L and 54R. Plugged it in and everything works. Gone to have to go fishing at the local yard for used one.