Hello my fellow Lexus-ers,

I have a question about mushy brakes and pedal sinking randomly to rhe floor when car is running.
I searched the forum for these symptoms but what I found is either too generic or it's not for the NX200t. I know the brake system is similar to all the models but I am looking for certain advice before going to spend on parts or labor.
The issue has been there ever since I purchased the car (second hand) in 2019.
This car had always spongy brake pedal although the sinking to the floor has started recently.
The jobs I did on the car, changed several times the rotors and brake pads. With the last change of rear rotors, I also changed the master brake pump, believing that it will fix the spongy pedal and sinking. Well, it did not. The issue is still there, same as before. Bled each caliper carefully with 20+ pedal pushes, in the mean time changed the brake fluid completely. I am out of ideas at this point. This issue started to get on my nerves to say the least.
I read somewhere that the ABS module needs to be bled as well and there are some tools out there that can perform this task.
I also read that a bad booster can give same symptoms that are similar to mine.
Braking is fine on the car. ABS kicks in when hitting the brakes suddenly, I can hear it working.
When the engine is off, the pedal is very stiff, but I believe this is normal since the booster is not activated.
One other issue that I observed is that whenever the rear brakes are applied (I have activated the automatic hand brake when stop and at stop light), the pedal is not spongy anymore, and the travel is much less.
Any advice?

 

Check your brake actuator serial number. Good luck!

 

Thanks for the answer, I will check it out today and respond.

 

I checked the numbers. I got 05S as the date, and the serial number is in the range, 010924. So, I guess this doesn't apply in my case. Thanks for pointing that out.

 

How did you release the rear electronic parking brake calipers to change the brake pads?

 

 

Very good. You performed one of the manual modes to retract the EPB without Techstream or an advanced OBD scanner.

I would try to bleed the brake actuator to see if that helps with your spongy brake pedal. Best of luck!

 

Thanks for your input!
I am putting it on techstream tomorrow to bleed the abs module, hopefully it will resolve the issue.

 

Anyone knows of a method to reset the brake booster or test it for that matter? I think I saw this somewhere in my research...

 

What's the current mileage on the vehicle?

 

175k km

 

Your vehicle is equipped with an electric vacuum pump instead of the engine vacuum for the brake booster.

The vacuum pump vane should be inspected at 120k miles per Toyota. Your vehicle mileage is almost there and it's not a bad idea to inspect the vacuum pump vane. I have attached the testing procedures for how to test vacuum pump vane and the brake booster.

Please don't quote my post since I'm going to delete the test procedures in 24 hrs due to copyright.

Best of luck!

 

Procedure to check for vacuum pump performance. If it is above the specs, then you probably can skip to check the vacuum pump vane. Let me know if it's below the specs.

 

Procedure to check vacuum warning switch.

 

Procedures to check brake booster and check valve.