dougpark714

Just got back from Tahoe and went for a car wash. I noticed the car did not have its lights on while going through the auto car wash. As it reached the end of the cycle, the car wash started to skip under the tires which means the car was probably in park mode, not neutral. I usually don't watch the car during the wash process but I strongly suggest others to watch.

I spoke to the mgr afterwards and he said his guys are trained for the different systems but admitted they sometimes get confused with all the different systems out there now. He was going to review the security tapes.

Car seems fine but does anyone know what kind of damage if any could be caused by going through the wash with the car in "park" mode? The strange thing is the tires rotated fine until it got towards the end when it locked up. I thought the tires could not rotate if the car is in park?

I have a feeling this happens more than people think. The bmw 550 in front of mine did not have its lights on either so I am assuming the same situation. Even if the lights are on, it's not a guarantee the car is properly set to neutral for the wash.

StevethePilot

I'm sorry but I'm missing how the lights being on or off show the car is in neutral or park? If I recall from my childhood days (literally, days - not weeks or months) of working at a car wash, the engine is left running so as to ensure a car which won't start won't block the tunnel, meaning a car with auto-on lights will have them on whether it's in park, neutral, drive, reverse ... whatever. If the auto-on lights are off, they are off no matter what. And if the car is off and in neutral, the lights will go off after a few moments if the engine is off.

I know this doesn't answer the question but I'm confused by the situation you have posited.

dougpark714

You're right, you can't tell if the car is in park or neutral based on the lights. But if you have your lights set to auto, the side marker lights should be "on" if the car is in neutral (or park) and the ignition is set to position 1 or 2. If you turn off the car "position 0", the lights will turn off (which was my case yesterday in the car wash) and the car will be in "park" mode. I don't think there's a way to keep the car in neutral while the car is fully off in "position 0".

Sorry for the confusion.

StevethePilot

Ahh! I did not know that! (I'll have to check this stuff out more thoroughly, I should know my truck better.)

dougpark714

Gets more complicated with keyless go. I usually take the keyless go button out at the car wash.

I don't understand how the wheels were turning when the car was in "park". I wonder if MB has a failsafe in case the car is towed in "park" mode.

Max Blast

According to the 7G transmission literature out there, when you put it in park there's a pawl that engages the output shaft. Nothing should turn freely, especially not the wheels. If it indeed was in park with the wheels turning freely you need to look for transmission damage. More specifically, a broken park pawl.

Max Blast

+1...Keyless has actually introduced more confusion than it was supposed to alleviate in my house.

dougpark714

Interesting. Transmission seems fine and "park" mode engages fine as well. No strange noises or leaks. I wonder if the park pawl is a wear item like brake pads. Or a mechanical pin.

I agree it's strange to see the wheels rotating. Could the car wash conveyer belt be that strong to push the suv in "park" mode? What's strange is the wheels locked up toward the end after the dry cycle. I wonder if there is a way to engage neutral mode while the car is turned off.

Max Blast

It most certainly is not a wear item...it's a mechanical arm that physically blocks the output shaft from turning. You'd hear it if it broke off, and it's a remove and replace the transmission type item...$$$$
Bottom line, if it's broken - that's bad. Sounds like you're in the clear though, since it engages.

03'55AMG

I can put my car in and out of any gear while no key is in with a hidden button

Max Blast

Good for you!

dougpark714

Thx Max Blast for the helpful info. Do you know if the park prawl locks all 4 wheels or just rear or front ones?

The reason why I ask is I thought I saw the left front wheel turn but perhaps some of the others were locked by the park prawl and were literally dragged by the car wash conveyer belt since it was slippery/soapy. But once it finished the dry cycle, there was sufficient traction to lock up the wheels causing the conveyer belt to skip under the left tires.

I'm done with automatic car washes. No more chances. I'll pay extra for a hand wash.

Max Blast

It only locks the output shaft of the transmission, so all driven wheels will as a result be locked. Over to the 4Matic experts on which wheels are driven, but your theory makes sense. Here's how it's put together:
http://www.mercedestechstore.com/pdf...%20cutaway.pdf

03'55AMG

Well I say it because if the lights aren't on, let alone the car, it can still be shifted

StevethePilot

... avoiding the joke ... avoiding the joke ... avoiding the joke ...

dougpark714

I checked the manual and there is no manual way to get the GL into neutral for towing or moving. So if your battery is dead or have major electrical issue, your car will be stuck in "park". Seems strange.

mdadgar

I think that's the point of the backup battery for the transmission, no?

- Mark

BACONMOTORSPORT

I am not sure what the car wash looked like exactly, but lets say the drivers side wheels are on a conveyor that hits against the back of the tires on the drivers side only. The tires do not spin as they are sitting on a belt or chain of sorts. The passenger side tires are meant to roll along on the floor. If the car was in park it would still move along since the diffs in the front and rear end are open, not mechanically locking, allowing the passenger side tires to roll. As soon as the car started off of the conveyor it would start to jerk and bind. Probably no damage done since you need to figure that they engineered the park pawl to hold the weight of the truck with a 7500# trailer on a hill.

03'55AMG

There is a way to override a trans to shift it with no power whatsoever. It is hidden, and not in the manual

Brocktoon

I though you said that yesterday...

03'55AMG

I did say that yesterday, but appearently he didn't read it

dougpark714

Apologies. Is the hidden button the 1/4 inch hole below the shifter with what looks like a recessed button? Any idea how it works?

dougpark714

Yes, the conveyer guide hits against the back of the tires on the driver side. But I don't think the tires were sitting on the belt. Instead, the guide pushes the car by applying pressure to the rear driver tire. I could be wrong but I thought I saw the driver side tires rotating -- I could not see the passenger tires. Car started jerking shortly after the dry cycle -- the conveyer guides behind the driver tires could not push the car and were hence forced to go under both rear and front tires. Attendant jumped in the car and drove off.

Interesting to hear about the open diffs in the front and rear end.

mdadgar

Well, you said it yesterday but didn't actually include the location of the button.

Which is, you know, not so helpful.

- Mark

monroerr

According to the manual for the 2013 GLK 250 BlueTEC there is a requirement to set the car in permanent neutral when going through a tow car wash. They state to remove the Keyless Go if necessary and switch the car on using the Smartkey. Then place it into neutral and make sure the parking brake is off. Then switch off the ignition but LEAVE THE SMARTKEY IN THE IGNITION SLOT.
Is the car wash really going to know this unless you are standing over them?