Release the brake pedal before you power-off! (really?...)

Interesting thing happened to me today, and i thought sharing it may be helpful. I pulled over at one point to pick up a phone call, and i powered off the car. Once i was done with the call, i tried powering back on, and... a whole bunch of interesting things started happen. Practically the car wouldnt start anymore, the gas (yeah right) pedal was blocked. I tried a few offs and ons, every time one or more indicators would come up, complaining about parking brake, ABS, brake fluid and so on. I called onstar at the same time (first time i used it) but they couldnt do anything about it. Eventually the car got going, but it still had a "service engine" light on.

I took it to the dealer during the lunch break, and left it there for the afternoon. Long story short (it was the first time for them to work on an electric sparky) they told me that while i was stopped, i probably had my foot on the brake (which i may have, since i was sitting in the car for the whole time). It looks like the electronics panicked, and thought that the brake circuit lost pressure. Which kinda makes sense, in a "known bugs that we need to fix" kinda way. Dealer recommendation: do not keep your foot on the brake pedal when you turn the power off. How much of a WTF is this to you?

Sounds fishy to me, as that is extremely common to do. Did you try it again to see if they weren't full of bologna?

Bryce

Actually it kind of makes sense. The brakes on the Spark EV are some sort of hybrid electro-hydraulic system. Not quite fly-by-wire, but the pedal mainly commands a level of braking (as does the traction control and stability control) and the actual effect is made up from a combination of regen and wheel brakes. So the wheel brakes are actuated by pressure from an accumulator of some sort not directly by pedal the pedal. Think of it as power brakes at one more remove. In an ICE car if the engine does not run the power brakes don't work. In the spark, there is no running engine so brake pressure in the accumulator is made up by a separate pump. I suppose that when the car is powered down the pump does not run and if you hold down the pedal it eventually discharges the accumulator.

The above is semi-informed speculation, I think it is correct enough to be useful as an explanation, but it may be in-accurate in some particulars.

I always have brake on when I power off b/c I'm on the hill. With no ill effects I might add.

On the other hand I ALWAYS forget to put that stupid dumb lever to Park position (because I don't have to do it with my intelligent Leaf) and the car starts to roll down and of course reminds me to do so.

it looks to be about holding the foot on the pedal for a longer time, not just having it on the brake when you power off. Bryce had the right idea, i will do it again just to make sure that the dealer didnt just come up with some BS. (i wonder if i should call the dealer before, and tell them what i'm gonna do.)

drivefast said:

it looks to be about holding the foot on the pedal for a longer time, not just having it on the brake when you power off. Bryce had the right idea, i will do it again just to make sure that the dealer didnt just come up with some BS. (i wonder if i should call the dealer before, and tell them what i'm gonna do.)

Click to expand...

So you can eliminate the possibility of getting stranded, why don't you do it at the dealer a couple of times and see if you can replicate the problem?

It seems to me that if the problem was a result of keeping your foot on the brake for an extended period of time, then powering down the car, there would have been several reports of it by now. I would wager that the problem was nothing more than one of those rare gremlins that show up on occasion in mechanical devices that involve computers, especially if they are new like the Spark EV.