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Discussion Starter #1
I have just put the car in for its latest service and MOT, when I went to pick the car up I did the normal thing put my foot on the brake pedal to push the blue start button and it went all the way to the floor. Now it has been in the garage since last Thursday and they are still no nearer finding the issue. Apparently if you drive the car the brake pedal works just fine, and it passes the MOT on the rolling road for brake function. However, the garage and I agree it's not right.

Has anyone else come across this issue and do you know what the solution might be?

Thanks
 

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Hi Ray,
Seemingly you are the only one to experience this 'new' phenomenon. I am following this thread closely though as my Ampera is having both MoT and separate 8th service this month.
 

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Discussion Starter #3
Hi Ray,
Seemingly you are the only one to experience this 'new' phenomenon. I am following this thread closely though as my Ampera is having both MoT and separate 8th service this month.
Hi Mike,

It's my 8th service also, still no news of what is wrong. I'll post here if and when I find out what the issue is/was and what the solution was, that is assuming they tell me.
 

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I'm no brakes expert, but sounds like there's a leak in the system that is cleared when the engine is running and the brake servo assist is running.

I assume garage are smart enough to check for fluid loss and keep an eye on your brake fluid levels before and after starting?

@donald might have an idea.
 

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Discussion Starter #5
I'm no brakes expert, but sounds like there's a leak in the system that is cleared when the engine is running and the brake servo assist is running.

I assume garage are smart enough to check for fluid loss and keep an eye on your brake fluid levels before and after starting?

@donald might have an idea.
The issue is when the car is off you put your foot on the brake pedal to turn it on, it goes to the floor. When it is on the pedal still goes to the floor. I did not want to try driving the car but I am told if you put it in gear and drive everything is OK and as I said originally it will pass an MOT rolling road braking test.

It did not do this before the service and they have checked the whole system several times for leaks and done (as far as I am aware) the fluid change at least twice.
 

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It did not do this before the service and they have checked the whole system several times for leaks and done (as far as I am aware) the fluid change at least twice.
Are you sure?

FWIW, I thought of this post and tested ... and my Ampera does the same!

I think at low speed what will normally happen in a FWD EV with regen is that the front brake circuit is isolated to permit max regen, and maybe this means there is a bypass circuit to compensate and allow the same brake pedal position and 'feel' as 'normal'. In turn, this might mean we all see this sort of effect.
 

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There is a bypass circuit on Ampera which is active above 5mph. Below that you get normal brakes. I think I have that right.

I cannot say if this is different to what you had before or not, but active EV foot pedals all (bar a few rare exceptions) seem to go right to the floor if you press them down, which I would not personally call 'normal' after decades of motoring, but, hey this is the brave new world, right?

It sounds to me like your brakes might actually be 'active' when you find the pedal goes to the floor, whereas before they were not. Maybe that was the update, to make brakes work 'Ampera-normally' when off, rather than not work 'Ampera-normally'. Sorry, not going to commit to this one, but suffice to say what I said before; there are various mechanisms to cut/reduce/engage the hydraulic circuits at low speed and 'anything' can happen in an EV. If it drives normally when powered up and driving, I am not sure what the question would be. Is it normal? No, EVs are very rarely designed to brake 'normally' (I think Tesla S and Fluence are the only exceptions I am aware of with independent 'normal' brakes.)
 

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The brake system is made by TRW specifically for hybrids, the pedal resistence you feel is generated by a hydraulic pump and accumalator so there are 3 possible problem areas, the pump, the accumalator or the control valves.
A forum member had the pedal go to the floor during normal driving while braking a mechanical backup applied the brakes dirt in a valve body was cited as a likely cause.
 

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Discussion Starter #9
Well I got the car back today and whilst the pedal still seems softer that it was before all seems to be in order. It certainly stops when on the road and you apply the brakes😀 It is certainly different to what it was the other day at least as far as I am concerned.

I gather that they did do another fluid change but there is nothing else to report - I cannot say if anything else was done or found.

So, all back in running order again, 8th service and MOT done - now I just need to ensure the lifetime warranty info is updated correctly.
 
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