When I push hard on my 08 FEH's brake pedal, I can feel it bottom out on the floorboard. At least that is what it feels like. The behavior is the same with the ignition on, or off. Is this normal?

 

No, this is not normal! It sounds like your brake module needs reprogramming or you may need a master cylinder replaced. It also sounds like what my brake pedal did after my brake ABS module was reprogrammed. Your required to do a brake pedal calibration by pressing on the pedal in "Park" as far as it will go. The Ford tech forgot that calibration requirement after the reprogramming and almost drove my FEH into a wall.

It could also be a fault in your PCM not calibrating your brake pedal. Go to the dealership as soon as possible.

GaryG

 

OK, I'll do that. Do you know if the system is fully hydraulic when the power fails? Like on non FEH's When other cars do this, it is a sign something is wrong with the hydraulics.

 

The brakes are power assist like normal brakes but the assist is electrical instead of vacuum. The intake valves stay open longer in our Atkinson cycle engine and doesn't create enough vacuum for the brakes and they wouldn't work during EV anyway.

If you lose electric assist, you still have hydraulics but it's hard to stop. If you can still stop, the hydraulics are still working. Since you are not getting any warning lights, I suspect the PCM is involved, although I would not rule out a bad master cylinder either. Test your brakes until you get it to the shop, and remember you have "L" to slow you down and a parking brake to help you stop. Just hold the parking brake release while using the foot parking brake pedal you have on your '08 if you lose hydraulics. If you don't feel good about driving it, call Ford roadside assistance to get it towed.

GaryG

 

The brakes seem to stop the car, even in an emergency stop. My experience is with the vacuum assist brakes. When the engine is off, you still have hydraulic brakes, and you cannot push hard and get the pedal against the floor. If you do, and the brakes are adjusted, it usually means a hydraulic problem.

I do have to really push on the pedal to get it to the stop, but I think it should never get there!

I'll takt it to the dealer today. If they have another hybrid on the lot, I will see if it's brake pedal has the same feel

 

BTW, I believe "regen" only affects the front brakes. The rear brakes are always active.

 

Well... regen affects all four wheels in the sense that it doesn't regen at the wheels. The motor drags on the end of the drive shaft acting as a generator... where that "negative" power would go is up to the differential, isn't it? so in effect if you have an AWD model, does't regen affect all four wheels? On the FWD model that wouldn't be true of course.... anyone know the answer to that?

I'm pretty sure its not true that the back ones are "always active"... but to be honest thats only a conclusion drawn from my memory of previous posts. Others that have the repair and service manuals would have a more definitive answer.

 

I don't think that the rear wheels, even on AWD models, provide any energy to the generator. Mostly because the hybrid part of the drive system, is the same between the FWD and AWD models. Plus, during braking, I don't think the AWD system, which does its "200 times a second" thing, is ever engaged.

From what I read here and on Yahoo, the rear brakes always being active, is the last "fail safe" in the braking system. If the regen system fails, and fails in a way that prevents all front braking, the rear brakes will eventually stop the vehicle.

 

Here is what the manual says guys:

"Since the regenerative braking uses the electric motor to slow the vehicle's front wheels, front brake pad wear is reduced. The rear brake pads, because of the regenerative braking, wear at approximately twice the rate of the front brake pads."

GaryG

 

So, does the fact that the rear wear at twice the rate support my thought that the rears are always in use (when braking)?