987dot3

As the title implies, I've got a bit of an issue. 2010 base 6MT 997 engaged the rear calipers while driving on the highway. After sitting, the rear brakes would release, but then lock up again after driving a few feet forward or backwards. Once towed home, I pulled the rear end apart and didn't notice anything unusual, but decided to rebuild the calipers, fresh fluid, etc.

I then decided I ordered a Durametric as it was clear that there wasn't a mechanical issue with the rear brakes. The ECU has a ton of stored codes, but the only ones that seem specific to this issue are:

4444: steering-angle sensor not initialized
c152: communication PSM control unit (drive)
c203: Fault steering wheel electric control unit (drive)

I lookes through as much live data as I could. So far, comparing side-by-side with my 987.2, I don't see any non-functional sensors. I tried unplugging the yaw sensor, checked all fuses, had battery tested and charged, and checked voltage manually and through Durmetric. All wheel speed sensor respond to forward and backwards movement and the yaw sensor is functional. I also briefly activated the ABS pump hoping that'd shake something loose.

I'm running out of ideas here short of buying a bootleg PIWIS or taking it to the dealership. I can't find a lot of information on how "drive off assistant" or hill hold works, but I assume the yaw sensor, brake, and clutch switch work together to determine when to hold, and the ABS pump closes off the rear lines until it's told to release?

Any ideas would be greatly appreciated!

Ob917

Crap sorry about your issue. I’d like to just permanently disable that feature in my car

Bruce In Philly

2009 C2S 191K miles

I hate that function. Back when I got the car, I looked into disabling it and could not find any information on it. Nothing I found in my Durametric either.

I have no idea why your car is doing this. I believe I read somewhere that the car senses it being on an angle (yaw sensor?) and I believe it is true given the years of dealing with it... but I have no idea where the tech is that determines this.

Peace
Bruce in Philly (now Atlanta)

ADias

Why is it an issue? Not asking if there's a malfunction, but when it does what's supposed to do.

Bruce In Philly

On a hill, my shifting skills are pretty good and quick. They are faster than the car can release and it is still annoying as hell to have to wait for the release. On steep hills, I know how to use the handbrake.

Peace
Bruce in Philly

ADias

I hear you but my experience with PDK is that there's no issues. Accelerate and the car goes.

Wayne Smith

A different reality for a MT.

Petza914

I'm adding this to the short list of .1 vs .2 benefits so those of us with the earlier cats can feel better about our choice

workhurts

It’s not terrible. Feels less intrusive than on my 981 and at least there’s a handbrake. On steep hills in the 981 I never trust it and I hate the ebrake …. but yeah if you have a hand brake what’s the point of it?

wjk_glynn

My experiences with hill-holds on my current PDK 997.2 and previous (non-Porsche) MT cars are quite positive.

Essentially you do all the normal steps (e.g. you slowly release the handbrake as you feed in the forward torque), and hill-hold just acts as a safety net in case you screw something up, or you’re a novice driver on a particularly steep hill.

When you put the car in gear, they’ll typically hold for up to 3-ish seconds to give you time to collect yourself, and you can pull away. If you’re an idiot and don’t do anything, your car will roll backwards after the 3-ish seconds expire.

Prior to the 3-ish seconds, they’ll release their hold immediately, basically as soon as the system detects there’s enough forward torque and clutch-clamping-force to progress.

For me, it was seamless (at least on MT BMWs from the mid-2000s, and current PDK car), and made life a lot simpler when living in San Francisco.

So how is the hill-hold on MT 997s bad? For example, does it not release when you’re feeding in adequate torque / releasing handbrake, and actually impede forward progress?

If so, that’d be terrible.

Thanks.

Karl.

PS: I grew up on a farm, learned to drive on 1960s Massey Ferguson, and I can slowly reverse that thing up a steep silage pit with a rear buckrake full of grass… just in case anyone was wondering if I knew how to feather throttle, clutch and brake

kellen

Agree with above. Pretty seamless on my car.

Jaws1

No complaints from me. Seems to work well.

Ob917

I agree it’s way to slow to release on a hill. I don’t need the help

wjk_glynn

Can you describe what happens?

Assuming you're feathering in the throttle and clutch, and balancing the parallel release of the handbrake...

In that case, are you literally blocked from progressing (including a risk of stalling) because the hill-hold won't release the brake for another second or two?

Thanks.

Karl.

Zepper