[bacampbe]

My wife was read-ended in the 2012 328i today. It was a moderately hard hit. The rear bumper is compressed, and there's some denting around the lower part of the trunk. Nothing unexpected, and I would have expected it to still be drivable. She is a little shaken, but otherwise fine.

Problem is, the car would not start afterwards. The brake pedal was partially depressed and hard. And we could not put the car (auto) into neutral. It had battery power, so I suspect both the failure to start and the transmission issue may have been due to a problem with the brake interlock for both.

So, is this normal behavior?

It was inconvenient at best. What should have been a "drive to the body shop on Monday" problem became a towing problem. The tow truck driver had to spend some time getting the car on and back off the flat bed.

At worst, it was dangerous, because she could not move the car out of traffic until the police and tow truck arrived.

[goj]

Sounds like the collision got into the exhaust and that potential caused some other chain reaction damage. Happened to my dad in his X5. Of course it's only speculation on my part. Sounds like you need to just find a local body shop to get it figured out for sure

[bacampbe]

Originally Posted by goj

Sounds like the collision got into the exhaust and that potential caused some other chain reaction damage. Happened to my dad in his X5. Of course it's only speculation on my part. Sounds like you need to just find a local body shop to get it figured out for sure

I can see how that would keep the engine from starting. But did that make the brake pedal act strangely, or keep the transmission from going into neutral?

In our case, the engine won't even turn over. Also, I forgot to mention that it gave a "chassis stability" warning when we tried (and failed) to start it.

It's sitting at the BMW dealer's body shop, waiting for people to show up Monday morning.

[goj]

Originally Posted by bacampbe

I can see how that would keep the engine from starting. But did that make the brake pedal act strangely, or keep the transmission from going into neutral?

In our case, the engine won't even turn over. Also, I forgot to mention that it gave a "chassis stability" warning when we tried (and failed) to start it.

It's sitting at the BMW dealer's body shop, waiting for people to show up Monday morning.

My guess is that the accident got into the brake lines

[bacampbe]

I just experimented with my car (an M235i), also with auto. You cannot move it from park to neutral if the engine is not running. That seems to me to be a safety-impacting design flaw: if the engine won't start, you cannot move the car.

How are you supposed to tow these cars without damaging the transmission?

[HFW003]

There is a "secret" way to get into neutral, I can't recall it but I do remember this discussion being had before.

[eluded]

have it totaled

[ajob]

Originally Posted by HFW003

There is a "secret" way to get into neutral, I can't recall it but I do remember this discussion being had before.

Yes, it's hidden in the manual under:

Driving > Steptronic transmission > Unlocking transmission lockout electronically

meant to move the car even if the engine does not start again.

A six step procedure... I wonder how one is supposed to remember all this after an accident!

If you have an iPhone you can keep there a full searchable manual for any recent BMW car by first dowloading a "Driver's guide" app, then follow easy instructions.

[xG35c]

Certain impacts can trigger a fuel pump shut off switch that needs a dealer reset.

[F32Fleet]

Originally Posted by ajob

Yes, it's hidden in the manual under:

Driving > Steptronic transmission > Unlocking transmission lockout electronically

meant to move the car even if the engine does not start again.

A six step procedure... I wonder how one is supposed to remember all this after an accident!

If you have an iPhone you can keep there a full searchable manual for any recent BMW car by first dowloading a "Driver's guide" app, then follow easy instructions.

Well if you have power you can search the manual via I drive or keep manual in the car.

[tturedraider]

Originally Posted by bacampbe

My wife was read-ended in the 2012 328i today. It was a moderately hard hit. The rear bumper is compressed, and there's some denting around the lower part of the trunk. Nothing unexpected, and I would have expected it to still be drivable. She is a little shaken, but otherwise fine.

Problem is, the car would not start afterwards. The brake pedal was partially depressed and hard. And we could not put the car (auto) into neutral. It had battery power, so I suspect both the failure to start and the transmission issue may have been due to a problem with the brake interlock for both.

So, is this normal behavior?

It was inconvenient at best. What should have been a "drive to the body shop on Monday" problem became a towing problem. The tow truck driver had to spend some time getting the car on and back off the flat bed.

At worst, it was dangerous, because she could not move the car out of traffic until the police and tow truck arrived.

The battery has a small explosive charge that disconnects it in a crash. It does not completely eliminate all power so the doors can be unlocked and the SOS center can connect with the driver. Your description makes me think of this.

[bacampbe]

Originally Posted by F32Fleet

Well if you have power you can search the manual via I drive or keep manual in the car.

Sitting with your car stalled in a busy traffic lane is probably not the time to be searching through the manual.

[bacampbe]

Originally Posted by __

The battery has a small explosive charge that disconnects it in a crash. It does not completely eliminate all power so the doors can be unlocked and the SOS center can connect with the driver. Your description makes me think of this.

Thanks for answering my original question--it looks like this behavior is to be expected.

But seriously? I can imagine a few situations where that would be a good thing--but a lot more (like this one) where it would not.

That reminds me; she says the SOS system activated, but never got a person on the other end.

[bacampbe]

Originally Posted by bacampbe

Sitting with your car stalled in a busy traffic lane is probably not the time to be searching through the manual.

I just searched the manual for my M235i (her manual is in her car at the body shop, but I assume it works the same way). It says the unlock process requires the starter to be able to turn over the motor. That was not the case, so it wouldn't have helped.

It seems like if the battery cutout that tturedraider mentioned activates, one would never be able to get the car out of park. If I understand things correctly, this is a pretty serious safety issue.

[//M]

Originally Posted by __

The battery has a small explosive charge that disconnects it in a crash. It does not completely eliminate all power so the doors can be unlocked and the SOS center can connect with the driver. Your description makes me think of this.

Originally Posted by bacampbe

Thanks for answering my original question--it looks like this behavior is to be expected.

But seriously? I can imagine a few situations where that would be a good thing--but a lot more (like this one) where it would not.

That reminds me; she says the SOS system activated, but never got a person on the other end.

Yes you're right about that but it should only go off in a severe accident, airbags are pretty much a requirement for that.

If there was airbag deployment that does seem like the likely cause.

OP unless this was a big big rear end accident, the battery charge should not have tripped.

[//M]

Originally Posted by goj

My guess is that the accident got into the brake lines

Nope, if it got into the brake lines the pedal would go soft not hard. What he's describing is the absence of the brake booster, the brake booster uses vacuum from the engine it also has a very small internal Reservoir that will allow assisted braking with the engine off one or two times. I'd assume his wife press the brake pedal a couple times trying to get it into neutral.

Is the shift lever still in Drive, if so that's why the engine won't start. I wouldn't worry about the brake pedal unless it stays hard once the engine starts.

[BMWrules7]

Originally Posted by bacampbe

Thanks for answering my original question--it looks like this behavior is to be expected.

But seriously? I can imagine a few situations where that would be a good thing--but a lot more (like this one) where it would not.

That reminds me; she says the SOS system activated, but never got a person on the other end.

The explosive charge does disconnect the battery as described.

I, too, often wondered about safety.


An assailant would only need to rear end the bimmer and presto the explosive charge renders the bimmer inoperable. Plus, the doors will automatically unlock to help the assailant even more.

[goj]

Originally Posted by tifosielia

Nope, if it got into the brake lines the pedal would go soft not hard. What he's describing is the absence of the brake booster, the brake booster uses vacuum from the engine it also has a very small internal Reservoir that will allow assisted braking with the engine off one or two times. I'd assume his wife press the brake pedal a couple times trying to get it into neutral.

Is the shift lever still in Drive, if so that's why the engine won't start. I wouldn't worry about the brake pedal unless it stays hard once the engine starts.

Interesting, besides the pedal stuff which I had no idea about, sounded the same as what I saw with my father's x5. That makes sense that it would go soft though

[bacampbe]

Originally Posted by tifosielia

Nope, if it got into the brake lines the pedal would go soft not hard. What he's describing is the absence of the brake booster, the brake booster uses vacuum from the engine it also has a very small internal Reservoir that will allow assisted braking with the engine off one or two times. I'd assume his wife press the brake pedal a couple times trying to get it into neutral.

Is the shift lever still in Drive, if so that's why the engine won't start. I wouldn't worry about the brake pedal unless it stays hard once the engine starts.

The brake part makes sense. But the car put itself into Park--probably when she released the seatbelt or opened the door. It was in park when she, and later I, tried to get it into N.

[bacampbe]

Originally Posted by tifosielia

Yes you're right about that but it should only go off in a severe accident, airbags are pretty much a requirement for that.

If there was airbag deployment that does seem like the likely cause.

OP unless this was a big big rear end accident, the battery charge should not have tripped.

I would call it a "moderate" rear-end impact, given the visible damage. I compare this to a prior read-end collision in her previous Acura TSX, where the trunk was pretty much gone and the rear-window smashed, but the car was still drivable. OTOH, maybe the bimmer just held up better structurally.

Would the air bags deploy on any read end collision? (Assuming no secondary collisions). I don't know if the other driver's air bags deployed.

[Beowulf65]

Originally Posted by bacampbe

I just searched the manual for my M235i (her manual is in her car at the body shop, but I assume it works the same way). It says the unlock process requires the starter to be able to turn over the motor. That was not the case, so it wouldn't have helped.

It seems like if the battery cutout that tturedraider mentioned activates, one would never be able to get the car out of park. If I understand things correctly, this is a pretty serious safety issue.

In the 435 2015 manual, it appears to be the same:

"Electronic unlocking of the
transmission lock
General information
Electronically unlock the transmission lock to
maneuver vehicle from the danger area.
Unlocking is possible, if the starter can spin
the engine.
Engaging selector lever position N
1. Depress the brake pedal.
2. Press the Start/Stop button. The starter
must audibly start.
3. Press and hold the selector lever into position
N.
A corresponding Check Control message
is displayed.
4. Press the selector lever again into position
N within approx. 6 seconds.
Position N is displayed in the instrument
cluster.
5. Release brake, as soon as the starter
stops.
6. Maneuver the vehicle from the danger area
and secure it against moving on its own."

[kd0t]

According to my SA, there's a button under the gear shifter surround that'll put the car in N. This is assuming there is power