Parking Brake unexpected Release (MT)

[Spart]

I also wanted to mention that when parking on an incline, after setting the parking brake, it's good practice to place the transmission in the opposite direction gear as the potential roll direction. Example, if parking nose-down, leave the transmission in REVERSE gear, and FIRST gear if you're nose-up. That way if the parking brake fails, the load path would be trying to turn the engine backwards, which needless to say, is much more difficult than the direction it's used to rotating in.

It's not really more difficult to turn the engine backwards, you'll get the same resistance from compression in the cylinders either way. However, there are some considerations. Reverse is often a different ratio than first. And turning an engine over the wrong way could cause it to jump timing depending on the design. Food for thought.

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[lucky phil]

I learned to live by the rule that "one is none, and two is one" with many things. Never rely on a single potential failure point if a second option is easily available.

I also wanted to mention that when parking on an incline, after setting the parking brake, it's good practice to place the transmission in the opposite direction gear as the potential roll direction. Example, if parking nose-down, leave the transmission in REVERSE gear, and FIRST gear if you're nose-up. That way if the parking brake fails, the load path would be trying to turn the engine backwards, which needless to say, is much more difficult than the direction it's used to rotating in.

Not a bad rule to live by there and one I subscribe to.
The engines resistance to rotation in reverse in reality is a bit less than in the normal direction of rotation because of the cam timing and cylinder filling. The engine doesn't fill the cylinders in the reverse direction as efficiently because the cam timing isn't timed for that DOR. The advantage of using reverse over 1st is that reverse gear is always a lower ratio than first gear and therefor harder for the wheels to rotate the engine due to the lower gearing.

Phil

 

[lucky phil]

It's not really more difficult to turn the engine backwards, you'll get the same resistance from compression in the cylinders either way. However, there are some considerations. Reverse is often a different ratio than first. And turning an engine over the wrong way could cause it to jump timing depending on the design. Food for thought.

I've never experienced that happening. It's true that rotating the engine in the correct DOR is what you always aim to do but I've never had an issue with the cam drive when I need to turn them in reverse direction by hand which you need to do at times doing cam timing. The main reason you avoid turning the engine in reverse is to do with the backlash in the cam drive system when doing cam timing and on some engines the sprag clutch for the starter motor engages and you also turn the starter which makes life harder.

Phil

 

[Kroberter]

Y’all are missing the point. Of course you can place it in park when you shut the engine off.
I’m complaining about the alarming moment when you role out of a parking spot when the engine is started without the intention of immediately moving.

 

[Kroberter]

Y’all are missing the point. Of course you can place it in park when you shut the engine off.
I’m complaining about the alarming moment when you role out of a parking spot when the engine is started without the intention of immediately moving.

In gear* I mean

 

[Jmanlevan]

I’ve had my MT for a few days now and I’ve tried to replicate the ebrake malfunction but I can’t get it to happen, which is obviously a good thing. So there is definitely something faulty going on with a few of the cars. Hope you all get it fixed as I understand that not being able to trust your parking brake totally sucks.

 

[Spart]

I’ve had my MT for a few days now and I’ve tried to replicate the ebrake malfunction but I can’t get it to happen, which is obviously a good thing. So there is definitely something faulty going on with a few of the cars. Hope you all get it fixed as I understand that not being able to trust your parking brake totally sucks.

Did you follow these steps exactly? Also make sure the doors are closed.

• Engine running, transmission in neutral.
• Set parking brake.
• Hold clutch pedal in.
• Touch brake pedal and release.
• Touch throttle pedal and release.
• Wait ten seconds or so.
• Release clutch pedal.

ETA: It's the system that allows you to drive away with the parking brake applied that's releasing the parking brake automatically, so you might also make sure that it's working as intended. Set the parking brake, then shift into first and try to drive away with it applied. It should automatically release.

 

[Supra_UK_]

Did you follow these steps exactly? Also make sure the doors are closed.

• Engine running, transmission in neutral.
• Set parking brake.
• Hold clutch pedal in.
• Touch brake pedal and release.
• Touch throttle pedal and release.
• Wait ten seconds or so.
• Release clutch pedal.

ETA: It's the system that allows you to drive away with the parking brake applied that's releasing the parking brake automatically, so you might also make sure that it's working as intended. Set the parking brake, then shift into first and try to drive away with it applied. It should automatically release.

^Sorry, just trying to think, I get that it's for testing purposes, but in BAU driving, when / why would you need to do that specific sequence of events?
Why would you touch the brake pedal if the parking brake is on in the first place? (To be clear, I pretty much never use the e-brake anyway unless I'm parked, or at a very long traffic light). I don't even use it at home, so the brakes never seize after washing and if I don't drive it for a few weeks I can just roll it a few inches to allow the tyre to not flatten, use a couple of 5 lb plates as chocks.

 

[Kroberter]

I have the brake release immediately on start up. Usually I wanna mess with the radio or hvac so it’s a little annoying I have to reset it to stay out without using my feet.

 

[Jmanlevan]

Did you follow these steps exactly? Also make sure the doors are closed.

• Engine running, transmission in neutral.
• Set parking brake.
• Hold clutch pedal in.
• Touch brake pedal and release.
• Touch throttle pedal and release.
• Wait ten seconds or so.
• Release clutch pedal.

ETA: It's the system that allows you to drive away with the parking brake applied that's releasing the parking brake automatically, so you might also make sure that it's working as intended. Set the parking brake, then shift into first and try to drive away with it applied. It should automatically release.

Yeah I followed it exactly and I tried every possible situation/combination I could think of and it held engaged each time when I wanted it to stay engaged. No issues. Seems like this is definitely an electrical issue or miscommunication in the system with those of you that are having issues.

and it is working as intended, where if I have it in first and try to drive away with it engaged, it will disengage automatically but with like a 1 second Hesitation and I get a little feedback that lets me know it’s engaged and then it disengages and the car pulls away as normal and intended.

 

[Spart]

^Sorry, just trying to think, I get that it's for testing purposes, but in BAU driving, when / why would you need to do that specific sequence of events?
Why would you touch the brake pedal if the parking brake is on in the first place?

It also functions the same way if you're holding down the brake pedal while you apply the parking brake, but for the purpose of giving concise instructions this was easier and gives the same effect.

 

[Spart]

and it is working as intended, where if I have it in first and try to drive away with it engaged, it will disengage automatically but with like a 1 second Hesitation and I get a little feedback that lets me know it’s engaged and then it disengages and the car pulls away as normal and intended.

Try driving away in first without applying any throttle (might help to be pointing slightly downhill.) Does the parking brake release?

If that works, try doing it again but leave it in neutral.

 

[NocturnalEmber]

Really interesting people are having this issue. My car has (so far) been completely trouble free, including with the e-brake. Has anyone tried to isolate this to a potential range of build dates?

 

[mkv.trav]

I just came across this older thread as I went searching to see if others have had this problem.
My 23 MT does this same thing. I turn the car on, take my foot off the clutch and the parking brake releases.
I’m used to it now so I just always keep an eye on it, but I was hoping it was a setting that could be fixed.
This definitely startled me the first time it happened because I was on a slight decline but I learned quick ?

 

[Spart]

I just came across this older thread as I went searching to see if others have had this problem.
My 23 MT does this same thing. I turn the car on, take my foot off the clutch and the parking brake releases.
I’m used to it now so I just always keep an eye on it, but I was hoping it was a setting that could be fixed.
This definitely startled me the first time it happened because I was on a slight decline but I learned quick ?

Please report it to NHTSA. They will not take action unless more people report. Toyota has already made it pretty clear that they do not care.

https://www.nhtsa.gov/report-a-safety-problem

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