Toyota mark x brakes at 20km/h

[João Gaspar]

Hi friends. I'm in Maputo, Mozambique and I have a 2005 Toyota Mark x for 7 years without any problem until now.  When I'm braking smooth the car and it reaches aprox 20km, it brakes sudentlly as if I make a stronger force on the breaking pad. But I'm keeping the same pressure. It happens always when the car is desacelarating by pushing the break pad and when it reaches 20km/h.  There is no problem with the brakes, discs or pistons.  

Any of you had this type of problem before? And how did you solved it? 

Thanks 

João 

Edited October 14, 2022 by João Gaspar
Corrections

[Yugguy1970]

Hard to say, could be some issue in the hydraulic system or it could be as simple as pitting or damage to the caliper sliding pins which is physically affecting the movement.

Pins are easy to change but very rarely replaced in my experience.

[João Gaspar]

Thanks for your quick response.  But we have checked that all breaking system including pins and everything is ok. Could it be something with the automatic gearbox when it reduces to the first gear? 

[flash22]

Remove the Battery for 15-20 mins and let the ecu's reset, does the car have ABS ?

[João Gaspar]

Yes it have abs. 

[João Gaspar]

I made more tests and I can confirm that the problem happens when we are breaking and the automatic gearbox switch from 2nd to 1 st speed around 20km/h. There is no strange noise. Just a sudentlly break. 

If I drive manually just at 1st speed, when I break and the speed lowers below 20km/h, the break does not happen. 

So it seams something with the automatic gearbox when it is reducing speeds. 

Does anyone knows what is happening and where is the problem? 

Is there any speed sensor in the gearbox that can be damaged? 

 

Appreciate any help on this issue.