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
Diagnosis code No.55 will be set
when the pump motor has been energized too long. The ASTC-ECU sounds the
buzzer continuously to inform the trouble of the driver and protects the pump
motor by activating the pump motor intermittently.
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
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STEP 1. Check the pump motor operation.
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When the ignition switch is turned to the LOCK
(OFF) position, check if the pump motor operates.
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Q.
Does the pump motor continue rotating?
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 Go to Step 2.
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 Go to Step 3.
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STEP 2. Check the pump motor operation.
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Remove the motor relay 1.
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Q.
Does the pump motor stop?
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Replace the motor relay 1. Then
go to Step 17.
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Go to Step 3.
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STEP 3. Check the pump motor operation.
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Remove the motor relay 2.
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Q.
Does the pump motor stop?
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Replace the motor relay 2. Then
go to Step 17.
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Go to Step 4.
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STEP 4. Check the power supply circuit at HBB harness connector
B-108.
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(1)Disconnect HBB connector B-108.
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(2)Measure the voltage between terminal 31 and body
earth.
OK: 0 volt
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Q.
Is the measured voltage 0 volt?
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Go to Step 6.
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Go to Step 5.
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STEP 5. Check the following harness wire.
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The wire between motor relay 2 connector B-12X
(terminal 4) and HBB connector B-108 (terminal 31)
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Q.
Is the harness wire damaged?
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Repair or replace it. Then go to
Step 16.
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Go to Step 17.
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STEP 6. Check the power supply circuit at HBB harness connector
B-107.
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(1)Disconnect HBB connector B-107.
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(2)Measure the voltage between terminal 2 and body
earth.
OK: 0 volt
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Q.
Is the measured voltage 0 volt?
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Go to Step 8.
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Go to Step 7.
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STEP 7. Check the harness wires between motor relay 1 connector B-13X
(terminal 5) and HBB connector B-107 (terminal 2).
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Q.
Is the check result normal?
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Go to Step 16.
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Repair or replace it. Then go to
Step 17.
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STEP 8. Check the following harness wires.
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- 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)
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Q.
Is the check result normal?
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Go to Step 9.
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Repair or replace it. Then go to
Step 17.
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STEP 9. Check the pressure switch (for pump motor control) circuit at
ASTC-ECU harness connector D-233.
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(1)Disconnect ASTC-ECU connector D-233 and measure at the
harness connector (component side).
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(2)Measure the resistance between terminal 11 and body
earth.
OK: Continuity (Less than 2 Ω)
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Q.
Is the measured resistance less than 2 ohms?
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Go to Step 10.
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Go to Step 13.
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STEP 10. Check the harness wires between HBB connector B-108 (terminal
35) and ASTC-ECU connector D-233 (terminal 11).
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Q.
Is the check result normal?
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Go to Step 11.
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Repair or replace it. Then go to
Step 17.
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STEP 11. Check the pressure switch (for pump motor
control).
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(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.
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(2)Disconnect HBB connector B-108.
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(3)Measure the resistance between the terminals 33 and 35 at
the HBB.
OK: Approx. 1 kΩ
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(4)With the HBB connector B-108 disconnected, turn ON the
ignition switch to operate the pump motor.?
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(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
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Q.
Is the check result normal?
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Go to Step 12.
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Replace the master cylinder and
hydraulic unit assembly (Refer to  ). Then go to Step 17.
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STEP 12. Check the pump motor operation.
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Q.
Does the pump motor operate?
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Go to Step 15.
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Go to Step 13.
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STEP 13. Recheck for diagnosis code.
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(1)Erase the diagnosis code.
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(2)Recheck for diagnosis code.
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Go to Step 14.
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The
procedure is complete.
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STEP 14. Check the harness wires between HBB connector B-107 (terminal
4) and ASTC-ECU connector D-233 (terminal 25).
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Q.
Is the harness wire damaged?
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Repair or replace it. Then go to
Step 17.
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Go to Step 15.
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STEP 15. Recheck for diagnosis code.
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(1)Erase the diagnosis code.
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(2)Recheck for diagnosis code.
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Replace the ASTC-ECU (Refer to
GROUP 35C, ASTC-ECU ). Then go to Step 17.
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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 .
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STEP 16. Recheck for diagnosis code.
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(1)Erase the diagnosis code.
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(2)Recheck for diagnosis code.
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Replace the HBB (Refer to ). Then go to Step 17
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The
procedure is complete.
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STEP 17. Recheck for diagnosis code.
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(1)Erase the diagnosis code.
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(2)Recheck for diagnosis code.
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Start over at Step 1.
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The
procedure is complete.
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