So, long story short, the brake lights on my 88 240 will not function
Here is what I have done:

Replaced/verified power at fuse
Verified power at brake light switch
Replaced bulbs
Replaced bulb failure warning sensor
New tail lights/circuit boards within last 12 months

Temporarily, I have wired the rear fog lights into the brake light switch and I am using the rear fog lights as my brake lights. Although this works just fine and gets me by, I would like to fix the core problem and have fully functional tail lights/brake lights

Does anyone have any idea of what the issue could be if it is not the brake light switch, the bulb failure relay, the fuse, or the bulbs? I am completely puzzled at this point... Everything else works just fine, as it should. Headlights work, interior lights work, ect.

The only other minor electrical issue I've noticed is occasionally when I turn the RIGHT (only right) blinker on, the hazard switch starts flashing in the car, but only the right blinker blinks.

Thanks!

 

Did you change the Bulb Failure Relay, the big red one? That'd be my guess... Make sure it's a good one.

 

I replaced the bulb failure warning relay with a working one out of my wagon, and a new one. No change.

 

Are you saying "power at bulbs"?
Yet no lights?
The only thing it could be then is bad ground(s).
I mean electricity is not that mysterious at least when it comes to 240 brake lights!
If you have POWER, +, then you need - which is the ground...

 

Sorry, I didn't not explain myself properly. I replaced with bulbs, and tested them in another 240 to make sure they would good. There is no power to the bulbs (including third brake light) when pedal is depressed. There IS power from switch, fuse, and relay ( bulb failure relay).

 

ok, there is a blue-red wire from the brake light switch to pin 9 of the bulb-out-sensor. a yellow wire goes from pin 11 of the bulb-out-thingie to a connector D, and yellow from there to the right brake light.

a yellow-green wire goes from pin 10 on the bulb-out-beercan through that same connector D and on to the left tail light, a blue-black wire goes from the left tail light to the 3rd brake light.

connector D is a 9 pin (3x3) thing under the dash near the fuse panel somewhere.

 

Thank you! I will start tracing it back this weekend.

 

I should add, the brake light bulb-out circuit is more sensitive than others. its wound unbalanced, since the left bulb plus center light draw more current than the right bulb, its designed to detect if ANY of those 3 bulbs has failed. now, nothing in the bulb out sensor should prevent the bulbs from actually working even if it stupidly thinks they are fubar.