Hey guys, I had somebody email me this asking a question, and I'm not sure what could cause this. Figured I'd post it here to see what yall said and I will forward it to him.
"I have a 2010 Highlander Sport, AWD and yesterday someone cut me off and I had to brake hard. Now the multifunction computer has a warning that comes up saying there is a brake malfunction, pull over and see dealer immediately. Full brake power seems to be there, no fluid leaks or other obvious signs of an issue. Pads are all new, changed 3k mi ago. The car has 57k miles so not covered under warranty. I am curious if this is something common with Highlanders and you have a suspicion to what it could be. Obviously since it is not under warrant anymore, I am trying to avoid a dealer's costs or local mechanic ripping me off. "
Probably had stability control and ABS kick in from trying to swerve and brake. No big deal. Tell them to get acquainted with the bells and whistles that the Highlander has.
Brake fluid in the master could splash forward and upward causing the float switch to trigger a low level. No leaks doesn't mean the level was full.
I hope that the brakes were completely bled with the pad change.
Brake fluid in the master could splash forward and upward causing the float switch to trigger a low level. No leaks doesn't mean the level was full.
the master cylinder has its own "mini" tank on top that I believe is meant to prevent that from happening. Plus on the actual brake fluid tank we can fill, the sensor is on the verybottom. It has to be bone dry to be tripped (even under severe nose dive)
He might get his HL checked to see if there are any codes present.
Braking is part of the over all VSC system and one of the computers or sensors might have a problem. The mechanical system seems to have done the job.
One computer component:
Quote:
Based on the signals from the master cylinder pressure sensor, the Skid Control ECU calculates the speed and the amount of the brake pedal application and then determines the intention of the driver to make an
Emergency braking. If the Skid Control ECU determines that the driver intends the emergency braking, the system activates the brake actuator to increase the brake fluid pressure, which increases the braking force.
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2008 Highlander Limited AWD, Silver, SmartKey, VSC/TRAK, Bluetooth, Remote Start, No Nav, Tow package/hitch/color matched fascia, roof rack cross rails, Color keyed mud guards, Camry trumpet horns
the master cylinder has its own "mini" tank on top that I believe is meant to prevent that from happening. Plus on the actual brake fluid tank we can fill, the sensor is on the verybottom. It has to be bone dry to be tripped (even under severe nose dive)
The reservoir does not have to be bone dry if it's designed like the reservoir in the Tacoma. Trust me on this...personal experience. Believe it or not, you'd think the baffles that are in the reservoir allow all that fluid to be used. Not so. I went ahead and flushed my fluid in the Tacoma after my light came on when slamming on the brakes to avoid hitting a deer. It then came on again at the next stop sign. When I checked the fluid, it was low (just below the min). Flushing the system, I discovered that there's a chamber in the front that does not get used when the reservoir gets low (which makes absolutely no sense to me). I was flushing the system and the reservoir would almost go dry while this front chamber stayed completely full. I had to use a syringe to drain and replace that fluid. So when the reservoir gets low, fluid can only splash in/out of this section upon acceleration/braking/bumps, etc. When you slam on the brakes, the fluid goes out of the main part of the reservoir and into this front section making the sensor "think" it's dry for a moment. At subsequent hard stops, it may/may not come on (depending on fluid level and how much makes it into that front chamber). Anyone flush their fluid yet in the HL to see if there's a front chamber setup like this on the HL?
EDIT: Granted, if the person already looked for any obvious signs of leaks, then I can't see low fluid as being the culprit in this situation. Sounds like they would have already checked that.
The reservoir does not have to be bone dry if it's designed like the reservoir in the Tacoma. Trust me on this...personal experience. Believe it or not, you'd think the baffles that are in the reservoir allow all that fluid to be used. Not so. I went ahead and flushed my fluid in the Tacoma after my light came on when slamming on the brakes to avoid hitting a deer. It then came on again at the next stop sign. When I checked the fluid, it was low (just below the min). Flushing the system, I discovered that there's a chamber in the front that does not get used when the reservoir gets low (which makes absolutely no sense to me). I was flushing the system and the reservoir would almost go dry while this front chamber stayed completely full. I had to use a syringe to drain and replace that fluid. So when the reservoir gets low, fluid can only splash in/out of this section upon acceleration/braking/bumps, etc. When you slam on the brakes, the fluid goes out of the main part of the reservoir and into this front section making the sensor "think" it's dry for a moment. At subsequent hard stops, it may/may not come on (depending on fluid level and how much makes it into that front chamber). Anyone flush their fluid yet in the HL to see if there's a front chamber setup like this on the HL?
Good to know about the sensor . I was thinking it was a major design fault if it had to go way below the min mark to reach the level of the sensor.
Front chamber... you talking about the mini reservoir on top of the master cylinder?
the toyota instructions on fluid replacement just say to fill the main reservoir to between min/max then bleed the lines/actuator/cylinder (continuing to fill between min/max while bleeding), they don't mention any auxiliary chamber/tank.
Ahhh, caught me again! I just popped the hood and the reservoir is completely different than the Taco. My bad. I need to spend more time under the HL hood. The HL has a much smaller reservoir than the Taco and it doesn't have any baffles in it. Guess they never expect it to get that low to where splashing/shifting fluid would ever be a problem...or maybe it's because it has the mini one on top of the MC? So ignore what I said about the baffles as it's not applicable to the HL. Next time I flush the Taco's brake fluid, I'll take a pic and send it to you because it's just bizarre how Toyota designed it.
But in looking at the HL, I could still see it getting triggered if you stomp on the brakes and the fluid is low. It happens.
The HL has a much smaller reservoir than the Taco and it doesn't have any baffles in it. Guess they never expect it to get that low to where splashing/shifting fluid would ever be a problem...it's just bizarre how Toyota designed it.
I google'd a pic of a tacoma's tank, and the baffles acutally kinda make sense (as long as they are vertices baffles) in that application. Thats a fairly large size fluid tank that is longest in the direction most effected by acceleration/deceleration. Without those baffles I imagine the fluid would be splashing everywhere. The tank does seem unusually large though (as does the highlander's). Older vehicle's tanks, that I've worked on, were much much smaller compared to these (Grand Cherokee for example, had a tiny reservoir).
To the others that provided suggestions I appreciate it - first thing I did was investigate fluid level and for leaks around brake lines, cylinders, etc. The HL is at the dealer. The error codes triggering the Malfunction Warning in the center Information Screen are not readable through a typical OBDII sensor. They have separate codes for the VSC systems, and this is a result of two codes. One was a result of when braking hard, there is a sensor on the brake pedal assembly that indicates pedal position as an input to the system that was damaged from the extreme force. Also bent the brake pedal which throws off the sensor. The second code they are waiting to hear from the Toyota Factory what it is linked to, most likely some other sensor damaged or malfunctioning.
I will post more details when work is complete.
The Following User Says Thank You to kennethpe For This Useful Post:
To the others that provided suggestions I appreciate it - first thing I did was investigate fluid level and for leaks around brake lines, cylinders, etc. The HL is at the dealer. The error codes triggering the Malfunction Warning in the center Information Screen are not readable through a typical OBDII sensor. They have separate codes for the VSC systems, and this is a result of two codes. One was a result of when braking hard, there is a sensor on the brake pedal assembly that indicates pedal position as an input to the system that was damaged from the extreme force. Also bent the brake pedal which throws off the sensor. The second code they are waiting to hear from the Toyota Factory what it is linked to, most likely some other sensor damaged or malfunctioning.
I will post more details when work is complete.
Wow...you must have been standing on that brake pedal! Interested to hear what the other code is actually from....
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2012 Limited Blizzard Pearl, Black Leather, Navigation (never get to drive it )
My HL isn't equipped with the brake override system, if I'm driving (foot on the gas) and I pump the brake - the brake will get hard and the that message will be displayed on the dash. Next time I push on the brake it goes away.
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