New owner of a 2000 RX 300. None of the rear brake lights are functioning during standard driving with the lights set to on. All bulbs function perfectly when depressing the brake pedal but when I let up, the they all turn off completely. At the point when they did work, briefly, the left turn signal was stuck on (no flashing, just steady on). Once this stops happened the blinkers continue to work normally but the brake lights stop working (In dim mode, the lights always work when I depress the brake pedal, in any light configuration)

I've checked each fuse relating to the lights.
Replaced all turn signal and brake light bulbs, including the high mount.
Checked the brake light failure module for any damage to pin #1, it looked fine, no discoloration or cracks.

Any other ideas? My left blinker and hazard lights also stop working randomly as well. Would the flasher relay have anything to do with the brake light failure?

TIA

 

Hi Mulazi, Welcome-to-Club-Lexus!!!

If someone has the complete schematic for this circuit I can give it a shot since I don't have full electrical schematic for this model.

There could be a problem in your headlight/turn signal stalk but would need to see the circuit and compare to your symptoms
to find a hack where these wires intersect to have somewhere to start.

Maybe someone else has been there and done that and has a fix for this please share.

 

Check for faulty 'Brake light failure sensor module'. Usually one pin fail. A soldering pencil will be needed to reflow the solder joint.

 

It wasn't that as I mentioned in my post. I did figure it out though. Sunroof drain flooded the back hub and it shorted out the trailer harness. All fixed now (Ditched the harness, I don't even tow anything).

 

I can only imagine how much work it was for this guy tracking down a problem like this! lol
PS- Awesome job Mulazi thank you for sharing your fix.
Are you saying water leaked on your hub under your car at the tow harness or inside the car at a factory harness junction just curious?

 

Yeah I just got fed up and started removing everything in the back and there it was lol a pool of water. Just the tow harness was affected!