[carl.csa]

Hi!

So, I have a 2010 E90 which is a manual car and I do know that these cars have a Start off Assist which prevents the car from rolling back. I dont really care about it but the fact that it is not working is weird. I dont have any lights on the dashboard so there is no reason for it not to work. The more weird thing is that when I wash the car, the feature works for a bit which is like one to two tries and then stops working again. Anyone has any idea what this could be?

I got the car two months ago and the brakes and rotors were replaced last year by the previous owner. Another thing which I noticed and not sure if it’s related to that which is also when I wash the car, there is a bang heard most probably from the rear. It only happens while the car is rolling back and it’s just like the brake pedal was pressed quick for a fraction of a second. Happens like 3 to 4 times in a row immediately after washing the car.

Not sure if it’s sensors related or there might be anything related to brakes (anything loose maybe). If anyone might have any idea about that or how the system works (what could cause bugs in the system) and can provide a cause for what my be causing that, I would really appreciate the help!

[Runnin'Rich]

mine doesn’t always work on my 6MT.

I find If i give the brake pedal a good stab it will engage. Coming to a rolling stop with a small amount of brake pedal won’t active it.

Try a steeper slope and give the pedal a firm push

[carl.csa]

Originally Posted by Runnin'Rich

mine doesn’t always work on my 6MT.

I find If i give the brake pedal a good stab it will engage. Coming to a rolling stop with a small amount of brake pedal won’t active it.

Try a steeper slope and give the pedal a firm push

Sounds good! Will try it tomorrow. Thanks for the advice!

[StradaRedlands]

I've come to really appreciate the hill hold feature... seemed like a gimmick, but it's pretty nice! I really notice it when I drive the Mazda3 that doesn't have it. Hope you can get it working consistently!

[Leucosticte]

Like the others in this thread. I found that I have to give the pedal a good push, was the same when my car was an automatic.

[carl.csa]

Originally Posted by Leucosticte

Like the others in this thread. I found that I have to give the pedal a good push, was the same when my car was an automatic.

Unfortunately, this didn’t help. Since it’s working a bit after washing the car, Im assuming that it might be a sensor issue somehow? Are there any sensors connected to the system? Cuz it seems that when they get some water it helps cleaning them up and the system works for some time.

[sabino56]

Like StradaRedlands I really like the feature. I’ve never messed with it but would assume there has to be sensing what gear you are in ,wheel rotation, foot on brake. Of course, BMW does things the BMW way so you’d have to dig into it to really know.

That said, maybe you can narrow things down.
I “think” the system works in both directions. I have memory of trying to back up a hill and it worked. (But I wouldn’t swear to it). It might be interesting to verify that and see if it works in reversing up a hill. If it does it would seem rotation, brake sensing wouldn’t be the problem?

There was a post from, I think @ctuna, which had some service training info. There might be something in there which explains the system.

If you can get access to INPA or IStA, I’d think there would be diagnostics which would likely tell you if some sensor is failed.

Good luck!