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Yaris braking problem Help Please!


kris11
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Please can I get some advice before I approach my main dealer.

bought car from new Yaris 2004 T Spirit, 54,000 mileage. When driving over 40mph if I brake the brake pedal has resistance around half way up. It feels as if the pedal is pushing back up.

Went to my local mechanic who changed the rear drums as they were excessively worn, bled the system but the problem persists. He put the car on a diagnostic machine and it shows no fault. He said he the discs and pads are fine too. He suggested my only option is to go to the main dealer.

Has anyone had anything similar? He believes it is a fault with the ABS system. Strangely no issues when driving slower and braking normally.

Thanks in advance of any guidance!

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I think you have a problem with your brake servo. A vacuum source from the engine is connected to the diaphragm ‘booster’ chamber with a rubber hose and a check valve. If the rubber hose or the check valve is leaking you can get a hard / soft / sinking action of the pedal. But what you are getting might be early signs of internal failure of the servo, with brake fluid leaking back into the servo inlet. Do you have to top up the fluid regularly or is there any signs of leakage around the master cylinder/ servo area? If you’re lucky you might get away with a hose or check valve. Otherwise you need a new brake servo and probably a master cylinder at the same time – that would make sense.

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Thanks for your input Tom.

My mechanic has said there is definitely no leak with the brake servo being fine. He also bled the brakes. He is convinced it is the ABS system in relation to the pedal?

Thanks anyway.

 

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Thanks for your input Madasafish. I have left a message with the mechanic asking if he bled the clutch. I'll update once I hear from him tomorrow.

He seems pretty convinced it is the ABS system but it just don't make sense as breaking below 40 mph everything feels perfect. Even when you brake at speed you feel push back on the pedal but it still brakes. He is adamant there are no leaks but what you say makes good sense. 

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When you apply the brakes normally, as pressure builds up in the master cylinder this generates a counter force against the servo push rod to close off the atmospheric port thereby maintaining a state of equilibrium. ie when you’ve applied enough pressure, want to maintain it and neither increase or decrease the braking effort.  Normally this reaction is well damped and you hardly notice it but if it becomes very noticeable then that is nor normal.

I would have said it’s difficult to see how the ABS can cause your problem, not impossible though. Let us know what the outcome is after investigation. 
 

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  • 3 years later...

I have just signed up for your club but am experiencing the same problem with my automatic 2004 Yaris. Mine happens at lower speeds.

The diagnostic machine does not through up a fault code. The mechanic says  it is the sensors thinking I am going into a skid. He has said he can change the sensors but that is expensive and may not be the cause of the problem.

Any suggestions ?  Please don’t be too technical as I have no knowledge of cars. 

 

Many thanks

Irene

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  • 3 weeks later...
  • 11 months later...

Please can someone advice what could be the issue with my 2008 Toyota Yaris. The car speed reduces and stop when you apply brake. Then the brake become hard and refuse to move even with the engine running.

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That sounds like the brake servo. With the engine off, pump the brake pedal a few times to remove the vacuum from the servo, the pedal should get quite hard. Put your foot on the brake and apply some constant pressure (as if you were stopped in traffic). Start the engine, if the servo is working correctly, you should notice the brake pedal gets lighter (i.e. the servo is working, giving you assistance when you press the brake pedal) and perhaps even drop a little. If there's an issue with the servo, the pedal will still feel hard with the engine running.

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  • 1 year later...

Hi, I have a similar issue with my 2004 1.0 Yaris. When I go to use the brakes, occasionally I will get a vibration/juddering in my pedal. It doesn't affect the braking performance very much if at all but it seem to be getting more frequent. It tends to happen when I'm coming to a stop from a slow speed but it's too inconsistent that when I try and explain it to anyone they all give me a different diagnosis. I am planning on bleeding my brake lines to see if it is something simple like air or dirt in there but would love some more input 

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Is the vibration you're getting the same kind of feeling as when the ABS engages? I've heard of issues on Mk1 Yaris' where the ABS kicks at low speed, though I've never had this on mine so never researched this myself. If it is a different feeling, it could be worth taking out the pads and the slider pins to grease them up - brakes need to be able to slide freely without binding to work properly. Bleeding the brakes may also be a worthwhile exercise, though that usually fixes issues with spongy pedals etc.

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If I've had any sort of feeling of judder from the brake peddle when braking it's always been the disc's being warped slightly, it feels like the brake peddle is pulsing under your foot.

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I’ve found - when braking over potholes or manhole covers, traction control kicks in causing pedal judder ( ABS activates).

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1st off, make sure your wheel nuts are tight, what condition are the pads and disks in ? A bit of rust under the top hat of the disc is enough to give vibrations under braking

lots of short journeys ? Take it for a long run and get some heat in the pads and disks

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