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Discussion Starter #1
I asked this question in my previous thread introducing myself and my RAV4, but didn't include the problem in the title, hence the re-post here....

I have a question about the dash brake light. The day I bought my new to me RAV4, it comes on and won't turn off. :mad: I made sure the parking brake was completely down, and the master cylinder is at least 3/4 full. Of course, I failed MD inspection because of it. Should I unplug the sensor in the master cylinder just to pass inspection? According to the inspection, the brake pads are in good shape and there are no leaks.

Thanks for any advice!
 

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I would check the switch at the parking brake.
Most are in a location that gets all sorts of stuff dumped on them. Plus it could be a cheap fix.
 

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Discussion Starter #3
Thanks Roundabout,

Ive looked online for a diagram or tutorial on reaching the parking brake switch. Im assuming its not super difficult - will I have to take apart the console?
 

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It could also be the low brake fluid level warning switch on the reservoir. This is a normally open switch, so disconnecting it should make the light go out if that's the problem.
 

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Discussion Starter #5
It could also be the low brake fluid level warning switch on the reservoir. This is a normally open switch, so disconnecting it should make the light go out if that's the problem.
I'd like to try that also, thanks. Is it just an obvious plug/switch on the side of the master cylinder?
 

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Discussion Starter #7
3/4 full fluid in the master cylinder may not be enough. Have you tried adding fluid?

I feel pretty dumb admitting this, but no, I haven't topped it off. That will be my next move first thing in the morning.


Quick update - I unplugged the sensor on the master cylinder and the light went off. Plugged it back in and it returned. Ill top off the fluid before I start asking about where to get a replacement sensor. :serious
 

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Discussion Starter #8
As it turns out, the master cylinder is actually slightly past the FULL mark. The light hits the plastic in a weird way so it looked a bit underfilled..

So the BRAKE light goes out when the float sensor is pulled out. The brakes and parking brake all seem to be working well and the pads are well within spec. If my next step is to source a new float sensor, how can I get a hold of one. A detailed search has yielded nothing. Also, it looks like the sensor is part of a larger harness, Would I have to buy a whole harness just to replace the sensor?
 

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Try going to a Toyota dealer and check out the part number and get a price quote. Then check online to source the lowest price.
 

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Sometimes the float can get stuck down if a brake flush was recently performed especially with a pressure bleeder. Try removing the screen and poking it with a small screwdriver. You may be able to free it.
 

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I'd just adjust the fluid level until it works since obviously the switch itself is good.
 

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Discussion Starter #13
I'd just adjust the fluid level until it works since obviously the switch itself is good.
Including removing fluid? Its filled to a bit above max. I'll jiggle the float form the inside in the morning and see if that does anything.
 

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Including removing fluid? Its filled to a bit above max.
Yes, that's all it might take. I have a few of those rubber ear syringes for just such small fluid transfers. I wrote "BRAKE FLUID ONLY" on one.
 

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I found in my previous vehicle the brake light was on because the parking brake cable was sticking. I couldn't tell from inside the car. I had the mechanic lubricate the brake cable under the car to resolve this. Too much grimme and crap causing the brake cable to stick.
 

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Since the OP has apparently found that the light goes out when the float sensor is removed and operated manually it should be a simple matter of adjusting the fluid level to that operating point.
 

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Discussion Starter #17
Since the OP has apparently found that the light goes out when the float sensor is removed and operated manually it should be a simple matter of adjusting the fluid level to that operating point.
This will be my next move for sure. Ill be able to get to it in the morning. Ill post results.
 

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Discussion Starter #18
Sucked out a half a big plastic syringe's worth of brake fluid to get the level to even. Played a little bit with the float but it seemed fine. Problem still exists. Where to look next?
 

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I thought you said the light would go out if you manually held the float at a right level. True?
 

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Maybe the float has lost it's buoyancy and sinks below the surface of the fluid.

Maybe the fluid has absorbed so much water, that the specific gravity has been reduced, causing the float to sink deeper than normal.
 
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