P mode vs Park mode

[Mario Veras]

What’s the difference between putting the Model 3 in P versus Park mode? I’ve seen some YouTubers talk about that it makes no difference, so why is there a logo displayed on the screen if it makes no difference?
I can’t seem to find this in the manual.

 

[Gauss Guzzler]

Given there is no way they are using a linear voltage regulation to control the motor, just what frequency averaging do you want that voltage reading at, and what kind of load do you expect (remember, this is a reactive load which doesn't obey ohms law).

Ask around at work, someone must have a voltmeter they can lend you. Set it to "DC" and it'll read a kHz bridge just fine. Did you say you're an electrical engineer?

You have a voltmeter too, right? Given you are so sure, it seems you must have data. What voltage does it apply for PARK vs BRAKE? I'll await your numbers, then I can go do the scientific method and see if my results match yours.

I told you the exact voltages and cited the data, but you insist on blindly believing your imagination and getting yourself all confused with Maxwell's equations instead of just acknowledging the simple facts. I suggest that you reach behind your tire with a voltmeter if you're so intrigued by all the quantum physics involved in running a simple DC motor. Until then, don't disagree with me without citing data - it's only fair.

 

[gearchruncher]

I told you the exact voltages and cited the data, but you insist on blindly believing your imagination and getting yourself all confused with Maxwell's equations instead of just acknowledging the simple facts.

You literally did not. Nowhere in this thread do you list a specific voltage you believe it runs at in two different modes. All you did was link to another thread, where the only reference to a voltage is:

There's also a sensor voltage that normally sits at 1.7V and goes up to 4.5V only during SuperPark, so this may in fact be a more secure stronger braking force.

Are those the voltages you mean? You think I am going to see 1.7V at the motor in normal park and 4.5V at the motor in SuperPark? From the instant I put it in park until forever?

And Maxwell's equations? Yeah, I brought those up because you said:

First, current is *always* proportional to voltage.

Which is completely false. But sure, divert the conversation to me making a DC motor more complex than needed, even though ohms law is irrelevant for DC motors and they won't work at all without Maxwell. Oh, but I forget, only brushless motors have back EMF. That's why golf carts with DC motors can go infinite speed, but Teslas run out of steam as they go faster.

But sure, let's take this to ohms law. The temp of the caliper motor could be -40C. It could also be 200C. Copper changes about 2:1 in resistance over this temperature range. Which means the current would change 2:1. Which means the torque changes 2:1.

Tell me, why would Tesla design this so poorly when they could do current control instead of voltage control?

Set it to "DC" and it'll read a kHz bridge just fine

What is a "kHz bridge" signal?

 

[Gauss Guzzler]

I didn't say current is *only* proportional to voltage, I said it is *always* proportional. Which is correct.

Also, no one cares about quantum physics here, it's just a simple motor. Are you going to tell me that my lug nuts aren't properly torqued because I didn't consider relativity?

Yes of course Tesla might adjust the voltage for temperature compensation or other factors. This could be from a simple lookup table, or it might be a feedback loop closing on a current shunt reading. Or maybe they just pick an ample voltage and stick with it. Who cares? It's not relevant to this topic. I know you're trying to get all pedantic with me because current is what technically produces torque but again, no one cares and neither does the system - it adjusts the *voltage*. Because current is always proportional to voltage.

Lastly, if you dig out your old textbook you'll see that PMDC motors are typically controlled by an H-bridge circuit, and on this scale they typically use switching frequencies in the kHz range. Which you can read for yourself with a volt meter. If you don't know any of those things and are wondering about linear regulators and back EMF and what frequency to read the voltage at, then you're not in a position to arbitrarily speculate that the data I presented is wrong simply because you feel like it is.

 

[gearchruncher]

I didn't say current is *only* proportional to voltage, I said it is *always* proportional. Which is correct.

It's kind of interesting how you seem to understand the existence of AC signals such as pulse width, the basics of how inductors and capacitors work, and I assume you believe in oscillating circuits and diodes, yet you continue to abuse the English language's definition of "proportional" to defend your silly statement.

But let's move on. I noticed you still have not posted the exact voltages you suggest will be seen at the parking brake caliper connector. Post your numbers and I'll go hook a voltmeter up to my car and make a video of exactly what voltages actually occur, and we'll end this with evidence.

 

[gearchruncher]

In case anyone thinks the noise difference is not due to a second actuation, go try it yourself.
Put the car in neutral (soft press up on the stalk from park).
Press Park. Listen.
Put the car in neutral. Press and hold park, and it will go into park+parking brake as indicated on the screen. Listen.

You'll hear no difference, despite one ending in just park, and one park+brake.

You only hear a difference if you engage the parking brake *after* already in park.

 

[mtmra70]

That noise does not mean its applying any new process or additional force. Much like electronic locks on a car.

Lock the doors (car other than Tesla) once and they make that classic "cla-chunk" sound. Lock them a second time and you hear a soft "click". That doesnt mean you car is extra locked or any more safe. It just means an event was triggered a second time and because the locks were locked, you hear relays and/or the attempt to lock them again. It's trying to move the lock mechanism but cannot.

The noise you hear is likely just the process attempting to move the brake actuator but not actually doing so.

 

[launchd]

That noise does not mean its applying any new process or additional force. Much like electronic locks on a car.

Lock the doors (car other than Tesla) once and they make that classic "cla-chunk" sound. Lock them a second time and you hear a soft "click". That doesnt mean you car is extra locked or any more safe. It just means an event was triggered a second time and because the locks were locked, you hear relays and/or the attempt to lock them again. It's trying to move the lock mechanism but cannot.

The noise you hear is likely just the process attempting to move the brake actuator but not actually doing so.

That analogy doesn't work here. Once you lock your car, you don't have an additional button to press that emergency locks your car, do you? You are pressing the same button twice in your example. Here, we are putting our car in Park (single button press) and then engaging the emergency brake (single button press and hold).

Some questions for anyone to answer if they think the two are the same...

Why are there two different functions (Park and emergency brake) and ways to engage them if they are the exact same thing?
Why is one able to be engaged at high speeds (emergency brake) but the other requires the car to be under approximately 1MPH (Park) if they are the exact same thing?
Why is one called Park and the other called SuperPark in CAN bus logs?
Why did a Model X roll back on a boat launch (incline) while towing a 5,000lbs boat in Park but, after engaging the emergency brake, this Model X did not move?

 

[gearchruncher]

Why are there two different functions (Park and emergency brake) and ways to engage them if they are the exact same thing?

Because 49 CFR § 571.135 requires, by law, a control for the parking brake that is independent of other controls. You may wish to actuate the parking brake while under motion, while "park" is only available when at zero speed.

Why is one able to be engaged at high speeds (emergency brake) but the other requires the car to be under approximately 1MPH (Park) if they are the exact same thing?

Park is not the same thing- it also disables the drivetrain. While parking brake only changes the brake system.

Why is one called Park and the other called SuperPark in CAN bus logs?

Because the can bus log names were made up by someone that doesn't work for Tesla. The CAN bus does not label itself. It's just something Jwardell came up with to try and define the difference between two sensor states in the CAN bus, but we don't know for sure. SuperPark is not a Tesla term in any way, shape, or form.

Why did a Model X roll back on a boat launch (incline) while towing a 5,000lbs boat in Park but, after engaging the emergency brake, this Model X did not move?

Because this car first went into park, and then the parking brake was used. This is TWO applications of the system. Just because it happened doesn't mean it's a purposeful part of the design that can be relied upon.

We will never know unless you go back and try the test I listed- which is to not do PARK and then BRAKE. But instead to put it in Neutral and go straight to BRAKE. Also, you must make sure you do all of this without your foot on the brake pedal at all. If it is on the pedal, you're helping the parking brake engage in some Teslas that use a shared caliper.

Now a question for you:
If activating the Parking Brake is purposefully designed to provide more holding force than just putting the car in park, why does Tesla not document this in any way in any of their manuals? Rathe than saying "when on a steep hill, use the parking brakes for extra holding power" what they actually say is "don't rely on them."

It's actually hilarious that people have been in this thread discussing how it uses the hydraulics, etc, when the manual literally tells you this isn't true.
What is also interesting is that Tesla treats activation via the stalk and the touchscreen differently. Using the touchscreen actively puts you in neutral, telling us that Tesla doesn't expect you to use the "parking brake" to walk away from the car at all, since they don't allow a car to be in neutral with nobody in the seat.

 

[mtmra70]

That analogy doesn't work here. Once you lock your car, you don't have an additional button to press that emergency locks your car, do you? You are pressing the same button twice in your example. Here, we are putting our car in Park (single button press) and then engaging the emergency brake (single button press and hold).

If the act of putting the car in park engages the parking/emergency brake, then the analogy works. The point I and others are trying to make is both processes are invoking the parking brake, thus why the sound is short and quick when going from "P" to "really P".

Why are there two different functions (Park and emergency brake) and ways to engage them if they are the exact same thing?

Legal requirements and/or supporting older cars that don't put the parking brake on?

When you put the car in park Tesla literally says the parking brake is enabled (2023 M3P). Why would they say its enabled when its not?

Why is one able to be engaged at high speeds (emergency brake) but the other requires the car to be under approximately 1MPH (Park) if they are the exact same thing?

Nobody said park is the same thing as the emergency brake. We are saying the emergency brake is applied when using park.

Why is one called Park and the other called SuperPark in CAN bus logs?

Because they are two different functions? I know if I was the programmer and someone said "hey, my car went into park while I was moving" I would want an easy clear way to understand if the "park" function was called or the "emergency brake" function was called. Also, no one is questioning Tesla's nomenclature....don't ask us why they called it "superPark"...lol

Why did a Model X roll back on a boat launch (incline) while towing a 5,000lbs boat in Park but, after engaging the emergency brake, this Model X did not move?

As requested earlier, did that person try going from N to emergency brake to see if it moved? Heck, my Subaru Ascent would every once in a while move after the e-brake was on and I release the brake pedal. Vehicles are allowed to settle.

I feel like this thread is stuck in a CRC loop...lol

 

[mtmra70]

View attachment 901110

Quoting my previous picture, as I think this drives an important note home.

When you put the car in regular "park", the car says the parking brake is applied. I'm not sure how this is not a slam dunk proof that the parking brake is applied?

 

[launchd]

Park is not the same thing- it also disables the drivetrain. While parking brake only changes the brake system.

Okay good, we're on the same page. Park and the emergency brake are not the same thing.

Because the can bus log names were made up by someone that doesn't work for Tesla. The CAN bus does not label itself. It's just something Jwardell came up with to try and define the difference between two sensor states in the CAN bus, but we don't know for sure. SuperPark is not a Tesla term in any way, shape, or form.

The CAN bus is simply an internal network that allows a car's computers/devices to communicate with each other. It does not define the terms being used by the software or firmware that these devices run, that is done by the manufacturer. SuperPark is 100% a term Tesla intentionally used.

Because this car first went into park, and then the parking brake was used. This is TWO applications of the system. Just because it happened doesn't mean it's a purposeful part of the design that can be relied upon.

We will never know unless you go back and try the test I listed- which is to not do PARK and then BRAKE. But instead to put it in Neutral and go straight to BRAKE. Also, you must make sure you do all of this without your foot on the brake pedal at all. If it is on the pedal, you're helping the parking brake engage in some Teslas that use a shared caliper.

Sorry what? The Model X went into Park on an incline (boat launch) while towing a 5,000lbs boat. The Model X rolled backwards when the driver took their foot off the brake. The driver put their foot back on the brake (to stop rolling) and engaged the emergency brake. Taking their foot off the brake once again, the Model X did not roll backwards. This would clearly indicate that the emergency brake is applying more clamping force (hence them not rolling backwards) to the rear calipers than Park did.

Now a question for you:
If activating the Parking Brake is purposefully designed to provide more holding force than just putting the car in park, why does Tesla not document this in any way in any of their manuals? Rathe than saying "when on a steep hill, use the parking brakes for extra holding power" what they actually say is "don't rely on them."

Because emergency parking brakes have all provided the same function in cars for a long, long time. Engaging them provides more stopping power than putting a car into Park. You typically engage them (or they auto-engage) when a car is on an incline or you need to stop quickly. Tesla stating what the purpose of an emergency brake is would be the same as Tesla telling you what the "gas" pedal does.

As requested earlier, did that person try going from N to emergency brake to see if it moved? Heck, my Subaru Ascent would every once in a while move after the e-brake was on and I release the brake pedal. Vehicles are allowed to settle.

I don't get it. Let me repeat what I said above for you so you can point out what part doesn't make sense/isn't proving a point. The Model X went into Park on an incline (boat launch) while towing a 5,000lbs boat. The Model X rolled backwards when the driver took their foot off the brake. The driver put their foot back on the brake (to stop rolling) and engaged the emergency brake. Taking their foot of the brake once again, the Model X did not roll backwards. This would clearly indicate that the emergency brake is applying more clamping force (hence them not rolling backwards) to the rear calipers than Park did.

Edit: You realize the reason traditional (ICE) cars roll backwards (or forwards) when you put them in park is because the parking pawl in the transmission is engaging the output shaft? This is not happening in a Tesla. If you put a Tesla into Park, you are not going to roll backwards (or forwards) unless gravity/weight are greater than the stopping force being used by the car.

 

[gearchruncher]

Okay good, we're on the same page. Park and the emergency brake are not the same thing.

Yes, but this does not mean that Park mode is not a superset that ALSO includes engaging the parking brake. Just like Tesla documents.

The CAN bus is simply an internal network that allows a car's computers/devices to communicate with each other. It does not define the terms being used by the software or firmware that these devices run, that is done by the manufacturer. SuperPark is 100% a term Tesla intentionally used.

100% wrong. Please go educate yourself on how the community has identified signals on the CAN bus, and what is transmitted on a CAN bus.
As Jwardell put it in his own post:

There is definitely a status mode dedicated to SuperPark (that's what I'm calling it!)

Why would he say that's what he's calling it, if in fact the CAN bus called it that? Why do DBC files exist if the CAN bus is self documenting?

Sorry what? The Model X went into Park on an incline (boat launch) while towing a 5,000lbs boat. The Model X rolled backwards when the driver took their foot off the brake. The driver put their foot back on the brake (to stop rolling) and engaged the emergency brake. Taking their foot off the brake once again, the Model X did not roll backwards. This would clearly indicate that the emergency brake is applying more clamping force (hence them not rolling backwards) to the rear calipers than Park did.

Like everyone keeps telling you, this is a SECOND application of the parking brake. Not proof that the parking brake is purposefully more capable than the park mode.

Because emergency parking brakes have all provided the same function in cars for a long, long time. Engaging them provides more stopping power than putting a car into Park. You typically engage them (or they auto-engage) when a car is on an incline or you need to stop quickly. Tesla stating what the purpose of an emergency brake is would be the same as Tesla telling you what the "gas" pedal does.

Except you're wrong again.
1) There is no such thing as an emergency brake legally. Only parking brakes. Please read 571.135 before commenting more.
2) "Park" in an automatic transmission is stronger than parking brakes. It literally hard locks the driven axle(s).
3) What are you talking about that you typically engage the parking brake on an incline or if you need to stop quickly? That's the point of the main brakes.
4) Tesla tells you the parking brake is on anytime you are in park. So since they only document parking brake, and tell you the parking brake is on when in park, why do they have this undocumented "stronger" parking brake mode?

Edit: You realize the reason traditional (ICE) cars roll backwards (or forwards) when you put them in park is because the parking pawl in the transmission is engaging the output shaft?

So you do know that Park in an automatic is stronger than the parking brake.....

 

[launchd]

Oof, alright - I'm tapping out, you win.

 

[mtmra70]

Edit: You realize the reason traditional (ICE) cars roll backwards (or forwards) when you put them in park is because the parking pawl in the transmission is engaging the output shaft? This is not happening in a Tesla. If you put a Tesla into Park, you are not going to roll backwards (or forwards) unless gravity/weight are greater than the stopping force being used by the car.

I said the emergency brake was on. Transmission is irrelevant at that point.

But again, the MX owner should retest, unless you are said model owner. It's really all hearsay.

 

[T4M3]

I am also convinced now, thanks for the discussion.

Your helpful guide to the Tesla Model 3 parking brake

These three things are true: 1. Whenever the car is put into Park (P), the parking brake is applied. You can call this "automatic parking brake" 2. If you press and hold the right stalk end-button for 3-4 seconds it will apply the parking brake if it is not already applied. If already applied...

teslamotorsclub.com

 

[mtmra70]

Woah woah woah, don't be linking to a thread that quotes the manual! None of that here!

 

[mtmra70]

Edit: Perhaps Tesla is using the electronic emergency braking system for both Park and the emergency brake? I don’t see why they would do this though.

Holy cow, that is what we have been saying...lol

When you put the Tesla in park it engages the emergency parking brake. The thread above has quotes from the manual stating that

 

[launchd]

I am also convinced now, thanks for the discussion.

Your helpful guide to the Tesla Model 3 parking brake

These three things are true: 1. Whenever the car is put into Park (P), the parking brake is applied. You can call this "automatic parking brake" 2. If you press and hold the right stalk end-button for 3-4 seconds it will apply the parking brake if it is not already applied. If already applied...

teslamotorsclub.com

Just so I'm clear, what are you convinced of? That thread states two different things. If you read page 3, it is full of responses that indicate the long press emergency brake engagement provides more stopping power. This is where the Model X owner assumed both modes were the same (post #46) until he experienced slippage during a normal Park engagement which he remedied by a manual emergency brake engagement (last post, #56).

 

[launchd]

Also, just so this is clear, I was wrong about Teslas using their hydraulic brake system to engage the brakes in Park... I think

Holy cow, that is what we have been saying...lol

When you put the Tesla in park it engages the emergency parking brake. The thread above has quotes from the manual stating that

Yes, I'm now aware that hydraulic brakes are not being used when you put your Tesla in Park, I admitted to this on the other page. I was confused about the brake pedal moving during a Park engagement. This confusion lead me to think that the hydraulic brake system was being used as I thought the pedal was being pumped.

I'm also aware that, if you put your Tesla in Park, the parking brake is engaged. However, you can engage the emergency brake after by using the long hold button press. What we are arguing about is if this is doing anything.

@gearchruncher is convinced that it doesn't do anything. You seem pretty convinced of this too. You both believe the parking brake and the emergency brake are the same thing and I'm 99% positive that it isn't. I believe (as others do and has been proven) that the long hold press engages the emergency brake (SuperPark) and clamps the calipers with more force than the parking brake, providing more stopping power.

 

[gearchruncher]

I believe (as others do and has been proven) that the long hold press engages the emergency brake (SuperPark) and clamps the calipers with more force than the parking brake, providing more stopping power.

Yet, Tesla has ZERO documentation of this in their manuals. Zero reference to an emergency brake. Just that you can either engage the parking brake by putting it in park OR pressing and holding. Same definition and description. Weird that a company would go to all this trouble for this feature, and then completely avoid telling users about it in any way or form.

"SuperPark" was made up by one Tesla owner looking at a CAN bus log. That is not proof. This is a made up name because they saw a "2" vs a "1" in a datalog.

You say there is proof- where is there proof that the calipers apply more clamping on the rotor when a long press occurs? A singular Model X not rolling after a complicated path of multiple parking brake actuations is not proof.