Hold Slipping into Park

[Snowball316]

Hello,

Just wanted to know if anyone else is having issues with their "Hold" feature. Starting with "2022.28.2" and going into "2022.36.2" I noticed that when I am parked on a light decline hill/driveway, I have the hold feature turned on and when I enable and pressing "parking brake" the car rolls forward a bit before actually stopping again. Is it just me or is there something mechanically wrong?

Thanks in advance. I hope I can confirm this actually "normal"

 

[Snowball316]

@Moderator - if you could update the subject to "Hold Slipping into Park" as the title. Please and thank you.

 

[Candleflame]

Hello,

Just wanted to know if anyone else is having issues with their "Hold" feature. Starting with "2022.28.2" and going into "2022.36.2" I noticed that when I am parked on a light decline hill/driveway, I have the hold feature turned on and when I enable and pressing "parking brake" the car rolls forward a bit before actually stopping again. Is it just me or is there something mechanically wrong?

Thanks in advance. I hope I can confirm this actually "normal"

the car doesnt have a parking brake. It just acuates the rear brake.

There is actually no difference between just getting out of the car and using the automatic Parking break and holding park and engaging the pseudo-parking brake (and getting the ! on the dash).

There are some rumours that manually activating it loosens the brake and applies it a bit tighter. But who knows. The manual calls both Parking Brake.

 

[jjrandorin]

@Moderator - if you could update the subject to "Hold Slipping into Park" as the title. Please and thank you.

(moderator note)

Thread title changed as requested. In the future, please use the report function to request this, as we sometimes miss requests posted in thread like that.

Thanks

 

[Snowball316]

the car doesnt have a parking brake. It just acuates the rear brake.

There is actually no difference between just getting out of the car and using the automatic Parking break and holding park and engaging the pseudo-parking brake (and getting the ! on the dash).

There are some rumours that manually activating it loosens the brake and applies it a bit tighter. But who knows. The manual calls both Parking Brake.

Ok thanks for the confirmation. I thought it was just my car. I never had a car hold, delay, and lock into "park brake" like that before.

 

[Gauss Guzzler]

"Hold" uses the brake booster to apply 4-wheel hydraulic brakes just as you would with your foot. You can even see the brake pedal move as it does so.
"Park" uses a jackscrew motor on each of the rear calipers to lock the wheels.

Some handoff occurs between the two methodologies when you shift from "Hold" to "Park" and while it ideally shouldn't allow for motion, the tuning might not be quite right. Apply the brake pedal before shifting if you are concerned.

Note that there is a much harsher transition that can occur if you engage park while driving up a hill at approximately 0mph. You'll immediately lose power and begin to roll downhill until the relatively slow caliper jackscrews engage. The car can easily roll more than a foot if the hill is steep and it is very alarming.

 

[Candleflame]

"Hold" uses the brake booster to apply 4-wheel hydraulic brakes just as you would with your foot. You can even see the brake pedal move as it does so.
"Park" uses a jackscrew motor on each of the rear calipers to lock the wheels.

Some handoff occurs between the two methodologies when you shift from "Hold" to "Park" and while it ideally shouldn't allow for motion, the tuning might not be quite right. Apply the brake pedal before shifting if you are concerned.

Note that there is a much harsher transition that can occur if you engage park while driving up a hill at approximately 0mph. You'll immediately lose power and begin to roll downhill until the relatively slow caliper jackscrews engage. The car can easily roll more than a foot if the hill is steep and it is very alarming.

sorry, again, whats the difference between using auto-parking brake and the manual parking brake?

 

[Gauss Guzzler]

The owner's manual and the screen icons both make a distinction between "Park" and "Parking brake". JWardell found that this distinction corresponds to a 260% increase in power sent to the brake caliper jackscrews. I assume Tesla chose to implement partial-strength and full-strength options to reduce wear and noise.

There's also an emergency brake mode anytime the button is pressed at speeds over 5mph. The major difference is that E-brake mode does not latch like the parking modes do - it immediately releases when the button is released.

That said, I don't think any of this is related to OP's original question regarding the transition from "Hold".

 

[father_of_6]

Note that there is a much harsher transition that can occur if you engage park while driving up a hill at approximately 0mph. You'll immediately lose power and begin to roll downhill until the relatively slow caliper jackscrews engage. The car can easily roll more than a foot if the hill is steep and it is very alarming.

Whoa... just want to make sure I understand.

Are you saying that if I'm facing up a steep hill and I pull up next to the curb between two cars and let the pedals go (and thus, am sitting still because of hold mode), then when I press "park" at the end of the year stalk my car will roll backwards more than a FOOT?

 

[Gauss Guzzler]

No, I said "while driving at approximately 0mph", not while in "hold" mode at 0mph. You have to stay on the Gauss pedal for this to occur.

As long as motor torque is moving the car uphill, hold mode will not engage the hydraulic brakes. Thus when you shift from D/R to P - while moving - the car will instantly cut power to the motors whilst simultaneously applying the parking brake. But the parking brake is kinda slow so there can be a brief freefall during the transition.

They should fix this by fading out the throttle input when shifting to P rather than immediately cutting all power. Or by using the (fast) hydraulic brakes to bridge the gap whenever shifting to P. But I don't know if they have made any attempt to address it yet since the last test I did a few months ago.