bkgthe1st

I just bought a 2005 RX330 and need to fix the CHMST, ie the 3rd brake light. The entire things is out so it's not a single bulb. All I've found on the Fuse is a 10A labeled STOP. But that, according to the fuse diagram, connects to several different systems at once. So is there another fuse solely for the 3rd/High Brake?

Lexuswiz

iTrader: (1)

I remember the whole 3rd stop light assembly is LED, also check if the LED assembly itself isn't shot since you already checked the fuse. I recall it was one fuse and that STOP fuse you checked was the one, if I still had mine I would have ran out there and checked lol

bkgthe1st

Thank you for confirming that. The fuse chart I'd found labeled the STOP fuse with a bunch of different systems which made no sense. Thus my confusion. I haven't removed the assembly yet, gotta track down my stubby screwdrivers to get it out. But I do know that there are 12 LED bulbs in it. I saw on another thread where someone suggested that they're wired in series so if one is out all of them are. Sadly the OP didn't come back later to confirm if that fixed his issue or not. But it's a lot less money than replacing the assembly so I'm going to buy a couple replacement bulbs and see if that fixes it or not. I'll let everyone know what I find.

DennisMik

The high mounted brake light does not have its own fuse. When you step on the brake pedal, the brake light switch sends power to the 3 lights. The one wire from the brake light switch splits into 3 wires in the rear of the car behind the rear seat.

What you want to do first is see if you have 12 volts at the high mounted brake light. If you do have 12 volts, then the light assembly is bad. As stated, the brake light is a bunch of leds. They ARE NOT wired in series. If one led goes out, the rest still work.

Lexus did not design the high mounted brake light to have easily replaceable individual leds. The leds are soldered onto a printed circuit board. If you are an electronic tech that repairs printed circuit boards, then it will be easy peasy for you. The only challenge you will have is to find the specific led that Lexus used. There are hundreds of different leds and Lexus isn't saying which one they used.