I have a 1989 240 sedan and the passenger side brake light is giving me trouble. Any help would be greatly appreciated!

The bulb works when the headlights are on, but will not work as a brake light. The rest of the housing unit lights up fine, as does the left housing unit (brake light included). I've tried the basics thus far, including changing the bulb, bulb casing, and light housing circuit pannel. No difference noted with the new circuit pannel. I lubricated the connectors as well, and this didn't work either. The fuse looks good with no corrosion or break.

Am I looking at a switch here, or perhaps a wiring issue? Thus far I am stuck, and since I have little electrical experience, a few pointers would greatly help.

 

Electricity always attempts to create a complete circuit.

If the lamp doesn't work with the lights off, but does when the lights are on, then you must be missing a ground connection. When the lights are on the brake lamp works because it is "borrowing" the ground path from the running lights!

On my 940 wagon, a black ground wire was broken that connected the body of the car to the lamp cluster. The lamps worked sometimes depending on what light were on. The Bulb Out relay put on quite a light show until I discovered the reason!!!!

Don't know specifically about the sedans, but a close inspection of the wiring may give you a clue as to where the ground path is missing.

 

Thanks, I'll try to work with the ground wires. However, would have the newer circuit pannel I installed (and then uninstalled) completed a proper ground as it has its own ground wire. Does any one know where the other grounds are, or perhaps a good wiring diagram for an '89?

Additionally, I think my original post needs clarification. The right sided dual filiment bulb works fine as an indicator that my headlights are on, but that's it! As a brake light, it does't work if the head lights are on or off. If the headlights are off, the bulb remains unlit with pressure applied to the brake pedal. If the headlights are on, the bulb is on, but won't get any brighter with pressure applied to the brake pedal.

 

The "bright" filament is not working, then. So with the additional information, I'd say that you may not be getting the 12V to the bright side of the bulb.

What happens if you install the suspect bulb & socket on the left side? (On my wagon you can switch them around)

If you can't swap the sockets, perhaps you could run a temporary wire from the left side to the right.

PS on my wagon the lack of a ground wire did not prevent the other lights from working!


HTH

Atwell "Sparky" Haines

 

Last I checked switching the bulb and sockets to the opposite sites yielded the same result, but I'll try it again to be sure.