Inspection Procedure

HINT:

When C1202/68, C1241/41, C1252/52, C1253/53 or C1391/69 are output together with C1256/57, inspect and repair the trouble areas indicated by C1202/68, C1241/41, C1252/52, C1253/53 or C1391/69 first.

1. CONFIRM DTC 
   1. Confirm output DTCs (see DTC CHECK / CLEAR  ).

      Result 

      RESULT CHART
      
      

      Result	Proceed To
      DTC C1256 is output	A
      DTC C1241, C1252, C1253, C1202 or C1391 is output	B

   B: CHECK CIRCUITS INDICATED BY OUTPUT DTC  (See DIAGNOSTIC TROUBLE CODE CHART  )

   A: Go to Next Step 

2. CUSTOMER PROBLEM ANALYSIS 
   1. Perform customer problem analysis to confirm whether if the customer was frequently braking when the brake warning light/yellow (minor malfunction) was illuminated.

      HINT:

      DTC C1256/57 may be output if the accumulator pressure drops due to frequent braking (this is not a malfunction).

      Result 

      RESULT CHART
      
      

      Result	Proceed To
      There was no frequent braking	A
      There was frequent braking	B

   B: Go to step  4

   A: Go to Next Step 

3. INSPECT BRAKE ACCUMULATOR PUMP 
   1. Turn the engine switch OFF.
   2. Disconnect the A23 and A24 accumulator connectors.
   3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance 

      TESTER CONNECTION SPECIFIED CONDITION CHART
      
      

      Tester Connection	Condition	Specified Condition
      A2 (BM1) - A4 (GND1)	Always	10 Ω or less
      B2 (BM2) - A4 (GND1)
      A2 (BM1) - B2 (BM2)	Always	Below 1 Ω
      A4 (GND1) - B1 (GND2)
      A2 (BM1) - A1 (MTT)	Always	950 to 1050 Ω
      B2 (BM2) - A1 (MTT)

      Fig 1: Identifying Brake Accumulator Pump Connector Terminals

      Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   NG: REPLACE BRAKE ACCUMULATOR PUMP  (See REMOVAL  )

   OK: Go to Next Step 

4. READ VALUE OF TECHSTREAM (ACCUMULATOR PRESSURE SENSOR) 
   1. Connect the Techstream to the DLC3.
   2. Turn the engine switch on (IG).
   3. Select the Data List mode on the Techstream.

      ABS/VSC/TRAC 

      ABS/VSC/TRAC REFERENCE CHART
      
      

      Tester Display	Measurement Kent /Range	Normal Condition
      Accumulator Pressure Sensor	Accumulator pressure sensor / min.: 0 V, max.: 5 V	Specified value: 2.6 to 3.8 V

   4. Depress the brake pedal 4 or 5 times to operate the pump motor, and check the output value on the Techstream with the motor stopped (not braking) for 30 seconds.

      OK: The accumulator pressure sensor voltage change is within 0.2 V. 

   NG: Go to step 5 

   OK: USE SIMULATION METHOD TO CHECK  (See HOW TO PROCEED WITH TROUBLESHOOTING )

5. PERFORM ACTIVE TEST BY TECHSTREAM (SMC1, SMC2, SLRRR, AND SLRRL) 
   1. Connect the Techstream to the DLC3.
   2. Turn the engine switch ON (IG).
   3. Select the Active Test mode on the Techstream.

      HINT:

      The Active Test can be performed when the following conditions are met.

      • Main relay 1 and 2 are on.
      • Shift lever is P position.
      • Parking brake is on.
      • Vehicle speed is 0 km/h (0 mph).

      ABS/VSC/TRAC 

      ABS/VSC/TRAC REFERENCE CHART
      
      

      Tester Display	Test Part	Control Range	Diagnostic Note
      Electronically Controlled Brake System Solenoid (SMC1)	Turns electronically controlled brake system solenoid (SMC1)	ON / OFF	Operation sound of solenoid (clicking sound) can be heard
      Electronically Controlled Brake System Solenoid (SMC2)	Turns electronically controlled brake system solenoid (SMC2)	ON / OFF	Operation sound of solenoid (clicking sound) can be heard
      Electronically Controlled Brake System Solenoid (SLRRR) Valve Close	Turns SLRRR solenoid	ON / OFF	Operation sound of solenoid (clicking sound) can be heard
      Electronically Controlled Brake System Solenoid (SLRRL) Valve Close	Turns SLRRL solenoid	ON / OFF	Operation sound of solenoid (clicking sound) can be heard

   4. Using the Techstream, turn SMC1, SMC2, SLRRR, or SLRRL ON.
      Fig 2: Brake Actuator Inner Diagram

      Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
   5. Check that each wheel cylinder's output value does not increase.

      OK: Each wheel cylinder's output value does not increase. 

      HINT:

      If any of wheel cylinder's output value increases, there may be a brake fluid leak in the brake actuator.

   NG: REPLACE BRAKE ACTUATOR  (See REMOVAL  )

   OK: REPLACE BRAKE ACCUMULATOR PUMP  (See REMOVAL  )