Inspection Procedure

HINT:

When C1253/53, C1254/54, or C1256/56 is output together with C1252/52, inspect and repair the trouble area indicated by C1253/53, C1254/54, or C1256/56 first.

1. CHECK PUMP MOTOR OPERATION 
   1. Turn the ignition switch off.
   2. Depress the brake pedal more than 20 times.
   3. Turn the ignition switch to the ON position.
   4. Check how the pump motor operates.

      Result: 

      RESULT DESCRIPTION
      
      

      Pump motor does not operate	A
      Pump motor operates continuously, and does not stop	B
      Pump motor operates intermittently	C
      Pump motor operates, then stops	D

   1. B: REPLACE MASTER CYLINDER SOLENOID AND BRAKE BOOSTER W/ ACCUMULATOR PUMP ASSY (SEE  OVERHAUL  ) 
   2. C: Go to step   4 
   3. D: Go to step   5 
   4. A: GO TO NEXT STEP 
2. CHECK CONNECTION OF THE PUMP MOTOR WIRE HARNESS (MT+/MT-) 
   1. Using a screwdriver, remove the 2 plugs from the hydraulic brake booster assy (SEE OVERHAUL ).
   2. Check the tightening torque of the 2 screws which tighten the wire harness connecting the hydraulic brake booster assy and the brake booster pump (SEE OVERHAUL ).

      OK: 

      Torque: 2.9 N.m (30 kgf cm, 26 in.lbf) 

   1. NG: TIGHTEN THE SCREWS UP, THEN GO TO STEP   5 
   2. OK: GO TO NEXT STEP 
3. CHECK RESISTANCE OF PUMP MOTOR WIRE HARNESS (MT+/MT-) 
   1. Using a screwdriver, remove the 2 screws and pull the wire harness from the hydraulic brake booster assy (SEE OVERHAUL ).
   2. Measure the resistance between the red wire (MT+) and the black wire (MT-).
      Fig 1: Checking Resistance Of Pump Motor Wire Harness

      Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

      OK: 

      Resistance: 2 Ω 

   1. NG: REPLACE BRAKE BOOSTER W/ ACCUMULATOR PUMP ASSY (SEE  OVERHAUL  ) 
   2. OK: GO TO NEXT STEP 
4. READ VALUE OF HAND-HELD TESTER (ACCUMULATOR PRESSURE SENSOR) 
   1. Connect the hand-held tester to the DLC3.
   2. Turn the ignition switch to the ON position and push the hand-held tester main switch ON.
   3. Select "DATA LIST" mode on the hand-held tester.
      ITEM, MEASUREMENT ITEM/RANGE (DISPLAY), NORMAL CONDITION AND DIAGNOSTIC NOTE
      
      

      Item	Measurement Item/Range (Display)	Normal Condition	Diagnostic Note
      ACC PRESS	Accumulator pressure sensor reading/min.: 0 V, max.: 5 V	3.58 to 5 V	If the value is constant regardless of pump operation, accumulator pressure sensor malfunction is suspected

   4. Check the accumulator output value.

      Result: 

      RESULT DESCRIPTION
      
      

      Output value is within the "Normal Condition" range	A
      Output value is out of the "Normal Condition" range	B
      Output value is constant regardless of pump operation	C

   1. B: REPLACE HYDRAULIC BRAKE BOOSTER (SEE  OVERHAUL  ) 
   2. C: REPLACE MASTER CYLINDER SOLENOID AND BRAKE BOOSTER W/ ACCUMULATOR PUMP ASSY (SEE  OVERHAUL  ) 
   3. A: GO TO NEXT STEP 
5. RECONFIRM DTC 
   1. Clear the DTC (see DTC CHECK/CLEAR  ).
   2. Turn the ignition switch off.
   3. Turn the ignition switch to the ON position.
   4. Wait for more than 5 minutes.
   5. Check if the same DTC is detected (see DTC CHECK/CLEAR  ).

      HINT:

      Reinstall the sensors, connectors, etc. and restore the previous vehicle conditions before rechecking for DTCs.

      Result: 

      RESULT DESCRIPTION
      
      

      DTC is output	A
      DTC is not output	B

   1. B: REPLACE BRAKE BOOSTER W/ ACCUMULATOR PUMP ASSY (SEE  OVERHAUL  ) 
   2. A: REPLACE MASTER CYLINDER SOLENOID AND BRAKE BOOSTER W/ ACCUMULATOR PUMP ASSY (SEE  OVERHAUL  )