ELECTRONICALLY CONTROLLED BRAKE SYSTEM Excessive Brake Pedal Travel (No Fluid Leaks and No Air in System)

CAUTION / NOTICE / HINT

PROCEDURE

1. PRE-INSPECTION

   
   

   1. Brake pedal inspection

      
      

      1. Perform a visual inspection and operate the brake pedal to check for any malfunctions.

      2. Check the brake pedal height, brake pedal free play and brake pedal reserve distance.

         Click here

         Tech Tips

         If the brake pedal height is not within specification, confirm that there are no other malfunctions before adjusting the brake pedal height.

   2. Brake inspection

      
      

      1. Check that the disc brake pads of each wheel are installed correctly.

      2. Check that the bleeder plug and union bolt is not loose, and that there are no damaged gaskets or brake fluid leaks, for each wheel cylinder.

   3. Brake fluid leaks and air in brake line inspection

      
      

      1. Check and take a note of the fluid level in the brake master cylinder reservoir assembly.

      2. Repeatedly depress the brake pedal and confirm that the brake pedal feels normal (no air in the system, etc.).

      3. Check if the brake fluid level in the brake master cylinder reservoir assembly has changed.

      4. If the brake fluid level has decreased, check for leaks due to damaged brake lines or hoses, loose union nuts, damaged brake master cylinder sub-assembly seals, etc.

   4. Bleeding air from brake system

      
      

      1. Bleed air from the brake lines and brake actuator assembly.

         Click here

      Result
      Proceed to NEXT

   
   

   NEXT

2. PERFORM ACTIVE TEST USING GTS (MOTOR RELAY)

   
   

   1. Connect the GTS to the DLC3.

   2. Turn the engine switch on (IG).

   3. Enter the following menus: Chassis / ABS/VSC/TRC / Active Test.

      
      Chassis > ABS/VSC/TRC > Active Test

      Tester Display	Measurement Item	Control Range	Diagnostic Note
      Motor Relay	ABS motor relay	Relay OFF/ON	Operating sound of motor can be heard

      
      Chassis > ABS/VSC/TRC > Active Test

      Tester Display
      Motor Relay

   4. Fully depress and hold the brake pedal.

      Tech Tips

      Make sure that the brake pedal has travelled excessively before holding it depressed.

   5. Operate the ABS motor relay using the Active Test and check if the brake pedal height changes when the pump motor is operating.

      OK
      The brake pedal height does not change (the brake pedal travel remains excessive).

      Result
      Proceed to OK NG

   
   

   NG

   REPLACE BRAKE ACTUATOR ASSEMBLY for LHD: Click here REPLACE BRAKE ACTUATOR ASSEMBLY for RHD: Click here

   OK

3. CHECK BRAKE MASTER CYLINDER SUB-ASSEMBLY

   
   

   1. Check that there are no brake fluid leaks and no indications of a malfunction in the brake master cylinder sub-assembly.

      OK
      There are no brake fluid leaks and no indications of a malfunction in the brake master cylinder sub-assembly.

      Result
      Proceed to OK NG

   
   

   NG

   REPLACE BRAKE MASTER CYLINDER SUB-ASSEMBLY for LHD: Click here REPLACE BRAKE MASTER CYLINDER SUB-ASSEMBLY for RHD: Click here

   OK

4. INSPECT BRAKE BOOSTER ASSEMBLY

   
   

   1. Inspect operation of the brake booster assembly.

      for LHD: Click here

      for RHD: Click here

      OK
      The brake booster assembly is normal.

      Result
      Proceed to OK NG

   
   

   OK

   USE SIMULATION METHOD TO CHECK Click here

   NG

   REPLACE BRAKE BOOSTER ASSEMBLY for LHD: Click here REPLACE BRAKE BOOSTER ASSEMBLY for RHD: Click here