Hello all. Had a little issue today and was curious to see if anybody has input for me. I tried searching around a bit but wasn't able to find anything relevant. 2010 G37x 7AT

Today, I drove to a family member's house and parked in the driveway. The driveway is sloped uphill, but not that steep. The car was in park, but without the parking brake on.
As I was shoveling snow around my car, it randomly started slowly rolling backwards down the driveway(as if the car was in neutral). Luckily I was right there with keys in pocket. I quickly unlocked and opened the door, pressed the brakes, and turned the parking brake on before it made it very far. Just to clarify, the car was actually rolling, not slipping or sliding on ice.

I'm very lucky that I was right next to my car when this happened, this could have been very bad had it happened at a different time or place.

So why did putting my car into park not work? Anybody have any thoughts or experience on this?
Thanks

 

This might best explain the possible issue. Could be the "parking pawl" or Shift linkage is not fully engaging the "pawl" to keep the car from rolling. I know my car will roll a little before the pawl hits and stops the car from rolling any further.

It is recommended if parking on a incline to firmly engage the parking brake first then put it into park so this does not stress the parking pawl overtime.

You may need to have a mechanic look into this if your not sure how to check the shift linkage and\or pawl

Transmission Parking Pawl - My AutomaticTransmission.com

 

Thanks svclee. That sounds about right.
I'm not sure why the pawl didn't engage this one time, but I can tell that it is still functioning otherwise. I'll definitely be a bit more cautious until I can confirm the parking pawl is fully functional.

Hadn't heard this advice before, thanks.

 

That is ALWAYS the way to do it. Get into the habit and when on an incline/decline you will keep the stress of holding 4000lbs still off the very expensive transmission. My wife learned the hard way even though I repeatedly reminded her. Now she parks that way all the time

 

FWIW, when parking, I hold the regular brake, place the transmission in neutral, set the parking brake "firmly" and then slowly let up on the regular brake to make sure the parking brake will hold the car. If it doesn't, I release and reset the parking brake more firmly so it will hold the car. Once I've convince myself that the parking brake is holding the car, then I put the trannie in park and turn off the ignition. That way, the parking brake is holding the car, not the parking pawl in the transmission, and there is little if any torque applied to the driveline while the car is parked. If the brakes do start to slip, the pawl will catch the car but the parking brake will still be holding most of the weight. As pointed out above, that transmission is pricey to fix.