2000 RX300. Light bulb warning indicator comes on after releasing brake pedal on engine start. Problem still exist even after replacing all brake light bulbs. Help!!!

 

I don't recall a brake light indicator. There is a brake warning indicator and a light bulb warning indicator. A common cause of the brake warning indicator is low brake fluid (or failed fluid level sensor). The fluid level declines as the brake cylinders expand due to brake disc pad wear. For the bulb failure warning, check all external bulbs (best at night), including reverse bulbs.

 

Brake fluid is properly serviced and all the brake bulbs were replaced including signal lights but the problem still exist. Thanks for your quick response.

 

Check the left and right and top mounted brake light.

If you have recently replaced the bulbs, check if they are the right rating (wattage). If one or more bul b is old, it could be on the verge of going out and drawing abnormal current causing the fail light to come up.

Salim

 

Exactly what indicator do you have on? As Bob2200 already mentioned there is no brake light indicator. There is a brake indicator (nothing to do with bulbs) or a lamp failure indicator which could be brake lamps or others.

 

Also could be a bad parking brake switch up under the dash. I had a defective brake fluid reservoir cap which caused the dash brake light to stay on and it kept the chime dinging.

 

This is the most important clue ... light comes on when brake is applied [engine start -> engine kill, resets the warning]. If I understand it correctly, it will happen on brake fluid falling low [on being sent to slave] or brake light sense circuit noticing less than expected draw.

Obviously the diagnosis over the net depends upon information provided.

Salim

 

I would not stress it to much. I keep getting an intermittent light (for the bulbs not the brake system) and can't find the "bad" one to save my life. I'm not sure what they use to trigger the warning light but they are all working fine on my car and I can go several days before it shows up again. I can clearly see both filaments lit up on the dual filament bulbs. I figure if I can't find a bad one then neither will a cop, so for now it's just an intermittent annoyance.

 

Well, I just looked in the manual and there is a "Light Failure Sensor" and a procedure to test the circuit. Looks like it is back in the hatch on the driver's side. Send me a PM and I can email you the test procedure.

The sensor is $257, so if it is the problem I would probably forget about it or pull the bulb in the dash. I suppose it will burn out on it's own eventually.

 

I agree with carguy07. It can be the sensor or most likely the current draw is off the refrence. The reference is set up in the sensor based on the current draw of good (and specified wattage) bulbs. Before the bulb actually pop, they can draw abnormal current, and visually produce light.

I too would suggest to leave it alone and keep an eye on the brake lights. There are 3 light sources, so there is safety built in.

Salim

 

im pretty sure the one he's talking about is the one that looks like the car from the top and then three little lines coming off of each tailight

i think the wifes rx is doing the same thing, i knew it had a tailight out and i changed that but i think its still doing the same thing...oh well

 

if you have replaced any of you bulbs with lower wattage bulbs or led's then it is possible that the light will stay on because there is not as much resistance in the system. It only takes about a half hour at most to remove the bulb from the dash, and that fixes the problem everytime.

 

Quick tip---Brake light indicator circuit boxes often fail.
Very expensive.
Quick fix/cheap fix----Open up the box and pull out the circuit board. locate the burnt resistor and replace/resolder.

 

Did not know that the circuit box often fails? I dont recall it being discussed in CL Forum. Does it happen when people use non-spec'ed bulbs?

Salim

 

Where did you get info on this failure? I have been here and on other Lexus forums for many years and this is the first I have heard of it.