SimonBr

Hi,

A newbie who found your forum while trying to search a problem.

My brake lights won't come on when the brake pedal is pressed. It's all of the lights.

I'm not mechanical but have changed the fuse (using a spare which was 25), the original is 20, and autozone suggested I changed the brake switch. At home it turned out of all the wrenches I have none would fit the nut. I was however able to unplug the old switch, plug in the new, and push the brake pedal but still none of the brake lights come on. I'm guessing it's not the brake switch. Anybody know where I should look next?

I should mention that no brake light warning light comes on in the dashboard. I've permanently had the 'check' warning light on. A few years ago even a Lexus mechanic couldn't figure out why.

I do have another problem with my rx300 although the brake lights problem is why I'm mainly here. The other problem is the AC doesn't work. The compressor was changed, and all the old fluid was sucked out and replaced. Some guy in an oil change garage with a big machine sucked all the old fluid out. So with a new compressor and fluids the AC still doesn't work. I do notice that with the AC off, sometimes I can still feel warm air blowing on my legs, at times it feels hotter. (I'm told you I'm non mechanical ha)

salimshah

My humble suggestion is to find yourself a good mechanic in your area.

If you are not mechanically inclined, only simple things can be worked out over the net.

Salim

SimonBr

I know of course that yours is the right advice but unfortunately right now I'm broke with a lot of crappy things going on in my life. Life isn't good. The last thing I needed was car repairs so I'm having to try and figure it out myself. I'm going to have to change the brake pads too, they've started warning me.

salimshah

I understand that rough times can befall us, but remember to count your blessings as things can be lot worse too and better times are bound to come. Nothing else it helps us all to develop a sense of empathy for others.

With multiple problems, you need to take care of the safety items first and live with some of the discomforts.

Brake lights are safety items as (depending on where you live) one gets rear ended even when the lights are working.

On your own you can check the fuses ... owner's manual will give you location for brake fuse.You can check them all.

Beyond that you will need wiring diagram and voltmeter and will have to trace presence of voltage when brakes are applied.

I vaguely recollect that there are two switches mounted on the brake pedal and there is an adjustment on those.

If you want to do the work yourself, you will have to have the right tools [metric size] and general know how + access to workshop manual. For general know how I highly recommend "Reader's Digest Complete Car Care Manual" ... I know it is old but it is cheap and with good info which never goes out of style.

Salim

carguy07

So you were able to plug in a replacement brake light switch and push the plunger in and it did not work? I'm confused when you say you pushed on the brakes and it did not fix it, if you could not install the new one, then pushing on the brakes would do nothing??

SimonBr

With the replacement plugged in though not bolted in, I pushed the plunger in by hand, while pushing the brake pedal with the other hand, and had somebody watching from behind the car.

The plunger doesn't have to pressed by via the brake pedal right? I could use my finger in testing that task?

Thanks in advance

carguy07

All you need to do is push the plunger in to make it work (or short out the wires).

SimonBr

Re the brake switch. Do any of you know if the brake switch has to be grounded to work? If so that may be why my attempt of pushing in the plunger using my finger failed.

Re brake light sensor. The Lexus parts dept told me there are two different types for an RX300. A Nippon Denser ($349), or a TEN ($379). The problem is because they're electrical they're non refundable and there is no way to test the sensor first to see if it's broken. We're supposed to just buy one and cross our fingers hoping that it's fixed it. If not we're stuck with it. btw The Nippon Denser brand is also used in IS300 models.

salimshah

You can do bench test with ohm meter or insitu test with circuit diagram and voltmeter.

Salim

SimonBr

That's to test the sensor right? That looks far too technical for me to even attempt.

Do you know if the brake switch needs to be grounded? It wasn't when I tested a new one so maybe that's why the new one didn't fix the problem?

Best regards,

salimshah

I am lost in terminology ..

Brake light switch ... mounted in the foot-well .... operated by brake pedal travel.

Brake lights in the tail (2 side and 1 top)

Brake light warning lamp ... in the instrument cluster.

If I understand your problem ... the brake lights do not lit up when brake is applied.

Basic diagnosis ... fuse ... brake light switch.

If you can upload a pdf of the brake light circuit and if you are handy with voltmeter, I can guide you further.

[note: I hope this does not confuse you further ... the brake/turn tail light wiring is different for Japanese and American cars.]

Salim