hard foot brake?

[ProfGlenn]

Hi.  Every few months or so, whenever I am almost at rest (e.g. in a  parking space), I'll go to drive off forwards or backwards and when I depress the footbrake it literally feels like there is a brick under the pedal.  If I lift my foot and depress it is then soft and normal.  I can't replicate it.  It's so odd.  I asked Toyota garage and although it had a full service in December they said they could try (at my further cost) to drain and refill all the brake fluid but that might have no effect.  I have never had this issue when driving at normal speed in 8 years of driving this car - although with the hybrid I have always felt that if you brake going over a speed bump it feels a bit weird.

 

Does anyone have any ideas what I might be experiencing please?  

 

I drive a 1.8 Auris hybrid, 2010 reg. 

 

Thanks

Glenn

[hdkagawa]

1 hour ago, ProfGlenn said:

Hi.  Every few months or so, whenever I am almost at rest (e.g. in a  parking space), I'll go to drive off forwards or backwards and when I depress the footbrake it literally feels like there is a brick under the pedal.  If I lift my foot and depress it is then soft and normal.  I can't replicate it.  It's so odd.  I asked Toyota garage and although it had a full service in December they said they could try (at my further cost) to drain and refill all the brake fluid but that might have no effect.  I have never had this issue when driving at normal speed in 8 years of driving this car - although with the hybrid I have always felt that if you brake going over a speed bump it feels a bit weird.

 

Does anyone have any ideas what I might be experiencing please?  

 

I drive a 1.8 Auris hybrid, 2010 reg. 

 

Thanks

Glenn

Are these parking spaces on a slight incline? sounds like the hill assist kicking in 

[ProfGlenn]

7 minutes ago, hdkagawa said:

Are these parking spaces on a slight incline? sounds like the hill assist kicking in 

Hi - no - flat.  Good suggestion though - thanks.

[Hybrid21]

Certainly the hybrid braking system does have it's quirks and sometimes makes me wonder, but it has been well tested 👍

[Cyker]

Usually if the brake pedal is hard in a car it's because the brake vacuum booster isn't providing any assistance, which I've experienced when I was in a very long downhill traffic jam in one of my old cars, where I just turned the engine off and used the foot brake for a while until suddenly the brake wouldn't go down and I had to pull on the handbrake to avoid crashing into the car in front!  

I later learned the vacuum in the brake booster had probably been used up, and without the engine running to replenish it, it just stopped working and I had to provide full braking force with just my leg!

 

There is one other thing in the hybrids - I'm not sure about the Auris, but in my Yaris Mk4, the brake system is brake by wire so the pedal doesn't actually do anything aside from tell the ECU how much I'm pushing it. However it has a fail-safe mode where the pedal directly acts on the brake master cylinder if the brake-by-wire system isn't working for some reason, which would feel like an un-boosted brake pedal.

I do wonder if there is a slight vacuum leak, as that's the only thing I can think of that might stop the brake-by-wire system from working without throwing a code...? The brake booster has a rubber diaphragm so it's not impossible for it to develop some leaks with age.

 

 

[ProfGlenn]

Thanks a lot for these replies - really appreciate the help thank you!

[Mooly]

Could it be a caliper sticking on its guide pins?

I remember some years ago on our old Corolla the brake pedal feeling 'hard' but more than that it had no free play, it just felt very solid as soon as you started to press it. Fixing the sticky front caliper restored normal operation and the free play returned.