Error | Incline too steep: parking brake may not hold

[dmfische]

Maybe Tesla got more data about the parking brake capabilities. Tesla is not known for super thorough testing before shipping cars, Elon model is "ship it and fix it later". This could just be that someone finally got around to checking what the max grade the parking brake can hold and added a warning to the software to wash their hands of any liability. Or, maybe as part of cost cutting the new parking brakes are weaker, but software has no way of knowing which ones you have installed, so warning is for shown to all. Or maybe it's a Model 3 feature which accidentally got turned on for Model S. It's really hard to tell with Tesla.

That said, a friendly warning to @thatisug , when you first park, the car's regular brakes may be engaged in addition to the parking brake (they for me are when I park on a much less steep driveway). After you get out of the car, the regular brakes disengage leaving just the parking brake ON. What that means that you may get out of the car, everything will seem fine, then the regular brakes will disengage and if the parking brake fails to hold the car, the car will roll down the driveway all by itself. Here is a video of my Model S parked on an icy driveway, where the rear wheels (the ones which have the parking brakes) were on ice, so after I got out of the car, when the regular brakes disengaged, the car rolled down the driveway - in my case only until the rear wheels got enough traction to stop the car, but if it was the parking brake failing, nothing to stop it.

It freaked me out when that happened btw, at first I thought maybe Summon got enabled (I always keep it disabled), so I pulled my driveway security cam and realized the rear wheels were locked and sliding.

I had this happen to me. Have a Dec 2018 S100D and parked it on a hill in icy conditions. Have winter tires but in retrospect the incline was a bit much given the conditions. Just as I closed the door, car slid backward 15’. Very lucky it didn’t hit anyone or anything.

I’ve looked through the manual and forums. Can anyone explain what the long press on the park button actually does other than turn on the indicator? Is there anyway to engage the front brakes when parked?

New to the forum and to Tesla. Other than this incident, I’ve been loving the car.

 

[Feathermerchan]

On my Model 3 (Sep 18) I can hear a sound like the rear brakes are being set when I hold the park button in. If it is just grabbing the rear caliper with another set of pads, then it is probably no help on a slope as the tires slide any way. Maybe some wheel chocks?

 

[MarkJ]

I’ve looked through the manual and forums. Can anyone explain what the long press on the park button actually does other than turn on the indicator? Is there anyway to engage the front brakes when parked?

Hi,
Long press of Park button is intended to activate the parking brake in an emergency, i.e. when moving.
When stationary it does nothing that a short press doesn't do. I'm not aware of any way to lock the front wheels as well.

 

[TSLA Pilot]

I would say there is definitely something more than just the brakes engaging. When I engage the braking “hold” on my significantly steep driveway and then engage Park the car moves forward a little as the hold brake is let off and the “Park” mechanism (however it functions) engages.

You're transitioning from ALL FOUR hydraulic brakes holding the car, to just the rear wheels, hence the slight shift in load. I'd be surprised if it moved a single mm, but you'll feel a subtle shift if you're observant.

But for you, and the OP, and the guy who had his Model S slide down his driveway in the video above, since the rear tires hold the car in place you will find it best to park facing UPHILL, not facing downhill (Why? As the Weight vector shifts on a slope, you'll find that more Force Normal on the rear wheels increases your car's holding power on very steep slopes--high school physics).

Depending on your date of manufacture, and your model, there could be a seperate set of parking brake pads on the rear discs, or the same pads used by the hydraulic brakes, but that's just FYI and not relevant here.

 

[RogerHScott]

OP after looking further in the manual that red circled P on your screen and the Alert is discussed here:

View attachment 392073 View attachment 392076

Isn't saying the brakes may or may not work not all that different from saying the accelerator is only a suggestion and the vehicle's actual acceleration is unpredictable, but you, the driver, are ultimately responsible for the movement of your vehicle? I don't recall any other car I've owned coming with a warning that the brakes may or may not work.

 

[SMAlset]

Isn't saying the brakes may or may not work not all that different from saying the accelerator is only a suggestion and the vehicle's actual acceleration is unpredictable, but you, the driver, are ultimately responsible for the movement of your vehicle? I don't recall any other car I've owned coming with a warning that the brakes may or may not work.

On a hill, I have in past ICE manuals. That's why you are suppose to angle your front wheels when you park because brakes can slip or go out.

 

[RogerHScott]

On a hill, I have in past ICE manuals. That's why you are suppose to angle your front wheels when you park because brakes can slip or go out.

Good advice, of course, when possible. But you're not always parked against a curb. I just wish they were a little more clear on how much of a hill was "a hill".

 

[jjh1234]

I had this happen to me. Have a Dec 2018 S100D and parked it on a hill in icy conditions. Have winter tires but in retrospect the incline was a bit much given the conditions. Just as I closed the door, car slid backward 15’. Very lucky it didn’t hit anyone or anything.

I’ve looked through the manual and forums. Can anyone explain what the long press on the park button actually does other than turn on the indicator? Is there anyway to engage the front brakes when parked?

New to the forum and to Tesla. Other than this incident, I’ve been loving the car.

My MS had the separate parking brake calipers. When placing the car into park, I could hear the mechanical sound of the parking calipers engaging. When I would hold P to get the emergency brake indication, I heard an additional mechanical sound that I assume was the parking brake calipers clamping down a little harder. I would assume this extra force, if that's what it is, would not be applied with the normal park to reduce war and tear on the parking brake. Just my guess.

 

[TSLA Pilot]

On a hill, I have in past ICE manuals. That's why you are suppose to angle your front wheels when you park because brakes can slip or go out.

That's because you've never owned another car as smart as a Tesla, and that knows the angle of road you're parking on, and probably even knows which way the car is facing--uphill or downhill . . .