Short story: It appears that if both parking brakes decide to stop working while you're driving, when you get to your destination the car will only shift into Neutral and will not shift into Park. Hopefully, I get to verify this theory later today.
FYI: 2015 Model S85D, ~120K miles
Longer version: Last Sat (12Dec) I got the parking brake 'fault' message. When I returned home I shifted the car in-and-out of Park/Reverse/Drive a few times and noticed that I could hear the parking brake activate on the passenger side only. I pulled the parking brake calipers off of both sides (to inspect/compare them) and noticed that the plastic motor cover was missing from the driver's side. It appeared that water had flooded the electric motor so that is possibly why it was not working. (Dammit, I didn't think to hook the right caliper up to the left connection to make sure the connection was working. Dammit. I'll find out tonight.) Anyway... so I ordered a driver's side assembly (which should be delivered today, 21Dec).
I was able to drive fine with the fault for the rest of the weekend, then to work Mon-Wed (145 mile commute, round-trip) of last week. Then on Thurs (17Dec) when I got to work the car would not shift into Park at all. I tried holding the Park button... nothing. I tried a hard reset, I tried opening the door while the car was in gear (Drive and Reverse)... nothing. The car would just shift into Neutral instead of Park. Since the car would now just ROLL, I parked against the curb and started making phone calls. The Tesla service center was SURE that I was mistaken, so I left work early to stop by the shop. They were able to see me right away since this is considered a SAFETY issue. Nice! When I got to the shop, they tried all of the same things that I tried yet the car would still only shift to Neutral.
Besides being able to roll away in Neutral, a couple of other issues I found is that the car could not be 'powered down' while in Neutral so your daytime running lights remain on. But the biggest issue (yes, bigger than not being able to shift to Park) is that since the car is not in Park, you can't open the charge door to charge the car. And even if you could open the charge door, the car still will not charge if the car is not in Park. The service guys said that they didn't even have a jerry-rigging way to work around that issue and they've never seen this happen to a car before. So I drive home with about 26 miles left in reserve.
I've come to the conclusion that the car waits for a signal from a pressure(?) or reed(?) switch in the brake assembly before the car actually shifts to Park. (I've never noticed if I heard the brakes actuate before or after the car shifts to Park. I'll have to look for that when it's fixed. Some of you can check now.) Since the parking brake signals between both sides are parallel, all will work fine as long as one brake is working. That's why I was able to continue driving over 4 days with a non-working driver's side parking brake. I'm 'assuming' that my passenger side brake failed on the drive to work. When I parked at work, since the car saw neither brake actuate, it wouldn't shift into park. "Maybe" that's a safety feature so that an owner doesn't get a false sense of security with the car being in "PARK" yet able to roll? I have no idea.
Anyway, I just noticed on my Blink cam that the FedEx guy just dropped off one of my brakes and the other should be in later today also. Once two working assemblies are installed, I'll find out if my theory is correct or if I'll need to 'creep' to the service center. (FYI, the car has been sitting since Thurs and the mileage has only dropped from about 15 to 11 miles in the 'tank' in 4 days. That's actually pretty good; especially, for cold weather (unheated garage). BUT, I also have a trickle charger (2 amp) hooked up to the 12V battery so that the high-voltage battery doesn't have to worry about keeping it charged.)
Fun stuff.
FYI: 2015 Model S85D, ~120K miles
Longer version: Last Sat (12Dec) I got the parking brake 'fault' message. When I returned home I shifted the car in-and-out of Park/Reverse/Drive a few times and noticed that I could hear the parking brake activate on the passenger side only. I pulled the parking brake calipers off of both sides (to inspect/compare them) and noticed that the plastic motor cover was missing from the driver's side. It appeared that water had flooded the electric motor so that is possibly why it was not working. (Dammit, I didn't think to hook the right caliper up to the left connection to make sure the connection was working. Dammit. I'll find out tonight.) Anyway... so I ordered a driver's side assembly (which should be delivered today, 21Dec).
I was able to drive fine with the fault for the rest of the weekend, then to work Mon-Wed (145 mile commute, round-trip) of last week. Then on Thurs (17Dec) when I got to work the car would not shift into Park at all. I tried holding the Park button... nothing. I tried a hard reset, I tried opening the door while the car was in gear (Drive and Reverse)... nothing. The car would just shift into Neutral instead of Park. Since the car would now just ROLL, I parked against the curb and started making phone calls. The Tesla service center was SURE that I was mistaken, so I left work early to stop by the shop. They were able to see me right away since this is considered a SAFETY issue. Nice! When I got to the shop, they tried all of the same things that I tried yet the car would still only shift to Neutral.
Besides being able to roll away in Neutral, a couple of other issues I found is that the car could not be 'powered down' while in Neutral so your daytime running lights remain on. But the biggest issue (yes, bigger than not being able to shift to Park) is that since the car is not in Park, you can't open the charge door to charge the car. And even if you could open the charge door, the car still will not charge if the car is not in Park. The service guys said that they didn't even have a jerry-rigging way to work around that issue and they've never seen this happen to a car before. So I drive home with about 26 miles left in reserve.
I've come to the conclusion that the car waits for a signal from a pressure(?) or reed(?) switch in the brake assembly before the car actually shifts to Park. (I've never noticed if I heard the brakes actuate before or after the car shifts to Park. I'll have to look for that when it's fixed. Some of you can check now.) Since the parking brake signals between both sides are parallel, all will work fine as long as one brake is working. That's why I was able to continue driving over 4 days with a non-working driver's side parking brake. I'm 'assuming' that my passenger side brake failed on the drive to work. When I parked at work, since the car saw neither brake actuate, it wouldn't shift into park. "Maybe" that's a safety feature so that an owner doesn't get a false sense of security with the car being in "PARK" yet able to roll? I have no idea.
Anyway, I just noticed on my Blink cam that the FedEx guy just dropped off one of my brakes and the other should be in later today also. Once two working assemblies are installed, I'll find out if my theory is correct or if I'll need to 'creep' to the service center. (FYI, the car has been sitting since Thurs and the mileage has only dropped from about 15 to 11 miles in the 'tank' in 4 days. That's actually pretty good; especially, for cold weather (unheated garage). BUT, I also have a trickle charger (2 amp) hooked up to the 12V battery so that the high-voltage battery doesn't have to worry about keeping it charged.)
Fun stuff.