Code No.55: Pump motor system (motor energized too long)
















OPERATION



  • The pump motor operates if the motor relay 1 or motor relay 2 turn to ON.
  • The ASTC-ECU monitors the pump motor (at 25 terminal).

DIAGNOSIS CODE SET CONDITIONS



PROBABLE CAUSES



  • Malfunction of the motor relay 1 or the motor relay 2
  • Malfunction of the pressure switch (for pump motor control) [Integrated with the hydraulic brake booster (HBB)]
  • Damaged wiring harness or connector
  • Malfunction of the ASTC-ECU
  • Malfunction of the HBB pump

DIAGNOSIS

STEP 1. Check the pump motor operation.
When the ignition switch is turned to the LOCK (OFF) position, check if the pump motor operates.

Q. Does the pump motor continue rotating?
Go to Step 2.
Go to Step 3.

STEP 2. Check the pump motor operation.
Remove the motor relay 1.

Q. Does the pump motor stop?
Replace the motor relay 1. Then go to Step 17.
Go to Step 3.

STEP 3. Check the pump motor operation.
Remove the motor relay 2.

Q. Does the pump motor stop?
Replace the motor relay 2. Then go to Step 17.
Go to Step 4.

STEP 4. Check the power supply circuit at HBB harness connector B-108.
(1)Disconnect HBB connector B-108.
(2)Measure the voltage between terminal 31 and body earth.
OK: 0 volt

Q. Is the measured voltage 0 volt?
Go to Step 6.
Go to Step 5.

STEP 5. Check the following harness wire.
The wire between motor relay 2 connector B-12X (terminal 5) and HBB connector B-108 (terminal 31)

Q. Is the harness wire damaged?
Repair or replace it. Then go to Step 16.
Go to Step 17.

STEP 6. Check the power supply circuit at HBB harness connector B-107.
(1)Disconnect HBB connector B-107.
(2)Measure the voltage between terminal 2 and body earth.
OK: 0 volt

Q. Is the measured voltage 0 volt?
Go to Step 8.
Go to Step 7.

STEP 7. Check the harness wires between motor relay 1 connector B-13X (terminal 5) and HBB connector B-107 (terminal 2).

Q. Is the check result normal?
Go to Step 16.
Repair or replace it. Then go to Step 17.

STEP 8. Check the following harness wires.

  • The wire between motor relay 2 connector B-12X (terminal 1) and ASTC-ECU connector D-232 (terminal 48)
  • The wire between motor relay 1 connector B-13X (terminal 1) and ASTC-ECU connector D-233 (terminal 24)

Q. Is the check result normal?
Go to Step 9.
Repair or replace it. Then go to Step 17.

STEP 9. Check the pressure switch (for pump motor control) circuit at ASTC-ECU harness connector D-233.
(1)Disconnect ASTC-ECU connector D-233 and measure at the harness connector (component side).
(2)Measure the resistance between terminal 11 and body earth.
OK: Continuity (Less than 2 Ω)

Q. Is the measured resistance less than 2 ohms?
Go to Step 10.
Go to Step 13.

STEP 10. Check the harness wires between HBB connector B-108 (terminal 35) and ASTC-ECU connector D-233 (terminal 11).

Q. Is the check result normal?
Go to Step 11.
Repair or replace it. Then go to Step 17.

STEP 11. Check the pressure switch (for pump motor control).
(1)Depress the pedal repeatedly more than 40 times until the pedal depressing force feels heavy with the ignition switch at the "LOCK" (OFF) position to release the pressure of HBB power supply system.
(2)Disconnect HBB connector B-108.
(3)Measure the resistance between the terminals 33 and 35 at the HBB.
OK: Approx. 1 kΩ
(4)With the HBB connector B-108 disconnected, turn ON the ignition switch to operate the pump motor.?
(5)During the pump motor operation, measure the resistance value (resistance value at high accumulator pressure) between the HBB-side connector terminal No. 33 and No. 35.
OK: 0 Ω

Q. Is the check result normal?
Go to Step 12.
Replace the master cylinder and hydraulic unit assembly (Refer to ). Then go to Step 17.

STEP 12. Check the pump motor operation.

Q. Does the pump motor operate?
Go to Step 15.
Go to Step 13.

STEP 13. Recheck for diagnosis code.
(1)Erase the diagnosis code.
(2)Recheck for diagnosis code.

Q. Is code No.55 reset?
Go to Step 14.
The procedure is complete.

STEP 14. Check the harness wires between HBB connector B-107 (terminal 4) and ASTC-ECU connector D-233 (terminal 25).

Q. Is the harness wire damaged?
Repair or replace it. Then go to Step 17.
Go to Step 15.

STEP 15. Recheck for diagnosis code.
(1)Erase the diagnosis code.
(2)Recheck for diagnosis code.

Q. Is code No.55 reset?
Replace the ASTC-ECU (Refer to GROUP 35C, ASTC-ECU ). Then go to Step 17.
It can be assumed that this malfunction is intermittent. Refer to GROUP 00, How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction .

STEP 16. Recheck for diagnosis code.
(1)Erase the diagnosis code.
(2)Recheck for diagnosis code.

Q. Is code No.55 reset?
Replace the HBB (Refer to ). Then go to Step 17 .
The procedure is complete.

STEP 17. Recheck for diagnosis code.
(1)Erase the diagnosis code.
(2)Recheck for diagnosis code.

Q. Is code No.55 reset?
Start over at Step 1.
The procedure is complete.