[GTM_Challenge]

Originally Posted by renfield90

I have a theory: what happened to me a week ago may have combined the panic brake feature along with ice mode.

When you trip the panic brake, the car decides the brake pressure for you - modulating doesn't have any effect. Then the other nannies (EBD, likely VSC, ABS) work at a layer underneath that - in other words, they aren't aware of whether the human is controlling the brake or the computer is controlling the brake, they simply respond to the conditions their sensors report. (As an embedded software engineer, this is more or less how I would implement the system. They're probably using an ABS controller from an older model without a panic brake feature and trying to integrate all the systems seamlessly for this one model is too much time/money.)

So if you're in panic brake mode and the ABS then trips ice mode, how do you handle this? Well, you are (apparently) in very real danger of hitting something and (apparently) there's not enough grip to stop the car. My thinking is that the system locks the brake pedal - if you're on ice trying to not hit something and you lock your wheels, you start running out of options very fast.

What happened to me was a LOCKED brake pedal and zero deceleration beyond engine braking. I can go out to my car, empty the reserve vacuum from the booster until the pedal is firm, but it will still have some give. Last week I tried to power through it and the pedal literally wouldn't budge. I'm not lacking for leg strength either.

I can live with "normal" ice mode. I can't live with this. The pedal dance disables panic brake so I'll be doing that from now on and we'll see if it happens again.

Any results on this? We've been getting the locked brake pedal even with the pedal dance. Going to try just pulling the ABS fuse this weekend to put the car into "No ABS Miata" mode - something I'm a little more comfortable with.