Code No.C1266: Motor malfunction (motor stick or open circuit)
Code No.C1273: Motor relay malfunction (open circuit)
Code No.C1274: Motor relay malfunction (short circuit)






caution
  • If there is any problem in the CAN bus lines, an incorrect diagnosis code may be set. Prior to this diagnosis, diagnose the CAN bus lines (Refer to GROUP 54C - CAN Bus Diagnostics Table .).
  • Before replacing the ECU, ensure that the communication circuit is normal.

OPERATION



  • ABS-ECU contains the power supply circuit (terminal No.13) for the pump motor. The pump motor is energised by the motor switch, which is incorporated in ABS-ECU.
  • The pump motor switch, which is incorporated in ABS-ECU, is always off unless the ABS operating or the motor solenoid valve check is activated when the vehicle is started.
  • ABS-ECU activates the pump motor by turning on the ECU built-in pump motor switch.

DIAGNOSIS CODE SET CONDITIONS



Code No. C1266
  • An open circuit has occurred to motor relay monitor.
  • Motor is seized.
Code No. C1273
  • At an initial start, the motor relay monitor judges the status of the motor relay as "OFF," and the motor is driven.
Code No. C1274
  • When the motor relay monitor judges that the motor relay is "ON" while it is "OFF".

PROBABLE CAUSES


Current trouble
  • Fusible link malfunction
  • Damaged wiring harness and connectors
  • ABS-ECU malfunction
Past trouble
  • Carry out diagnosis with particular emphasis on wiring harness and connector failures between the power supply circuit (A-01 ABS-ECU connector terminal No.13) to the ABS-ECU motor and the earth circuit (A-01 ABS-ECU connector terminal No.12 and No.24). For diagnosis procedures, refer to How to treat past trouble (GROUP 00 - How to Cope with Intermittent Malfunctions ).

DIAGNOSIS PROCEDURE

STEP 1. M.U.T.-III CAN bus diagnosis
Use M.U.T.-III to diagnose the CAN bus lines.

Q. Is the check result normal?
Go to Step 3.
Repair the CAN bus lines (Refer to GROUP 54C - CAN Bus Diagnosis Table .). On completion, go to Step 2.

STEP 2. Diagnosis code recheck after resetting CAN bus lines

  • Erase the diagnosis code.
  • Drive the vehicle at 10 km/h or more.

Q. Are diagnosis codes No.C1266, C1273 or C1274 set?
Go to Step 3.
This diagnosis is complete.

STEP 3. Connector check: A-01 ABS-ECU connector

Q. Is the check result normal?
Go to Step 4.
Repair the defective connector. Then go to Step 9.

STEP 4. Fusible link check: Check the fusible link No.22

Q. Is the check result normal?
Go to Step 6.
Go to Step 5.

STEP 5. Resistance measurement at A-01 ABS-ECU connector
(1)Removal the fusible link No.22.
(2)Disconnect the A-01 ABS-ECU connector.
(3)Measure the resistance between the terminal No.13 and the body earth.
OK: No continuity

Q. Is the check result normal?
Replace the fusible link No.22. Then go to Step 9.
Repair the harness between the fusible link No.22 and A-01 ABS-ECU connector terminal No.13. Then replace the fusible link No.22. Then go to Step 9.

STEP 6. Voltage measurement at the A-01 ABS-ECU connector
(1)Disconnect the A-01 ABS-ECU connector.
(2)Measure the voltage between the terminal No.13 and the body earth.
OK: Battery voltage

Q. Is the check result normal?
Go to Step 7.
The open circuit may be present in the pump motor power supply circuit. Repair the wiring harness between the A-01 ABS-ECU connector terminal No.13 and the fusible link No.22. Then go to Step 9.

STEP 7. Resistance measurement at A-01 ABS-ECU connector
(1)Disconnect the A-01 ABS-ECU connector.
(2)Measure the resistance between the terminal No.12 and the body earth, and between the terminal No.24 and the body earth
OK: Continuity exists (2 Ω or less)

Q. Is the check result normal?
Go to Step 8.
An open circuit may be present in the earth circuit. Repair the wiring harness between the A-01 ABS-ECU terminal No.12 and the body earth, and between the A-01 ABS-ECU terminal No.24 and the body earth. Then go to Step 9.

STEP 8. Check whether the diagnosis code is reset.

  • Erase the diagnosis code.
  • Drive the vehicle at 10 km/h or more.

Q. Are diagnosis codes No.C1266, C1273 or C1274 set?
Replace the hydraulic unit (integrated with ABS-ECU) (Refer to ). Then go to Step 9.
Intermittent malfunction (Refer to GROUP 00 - How to Cope with Intermittent Malfunctions .).

STEP 9. Check whether the diagnosis code is reset.

  • Erase the diagnosis code.
  • Drive the vehicle at 10 km/h or more.

Q. Are diagnosis codes No.C1266, C1273 or C1274 set?
Return to Step 1.
This diagnosis is complete.