Code No.C1266: Motor system
Code No.C1273: Motor relay (stuck off)
Code No.C1274: Motor relay (stuck on)
Code No.C1280: Motor fail-safe relay (short circuit)





caution If there is any problem in the CAN bus lines, an incorrect diagnosis code may be set. Diagnose the CAN bus lines before the diagnosis codes (Refer to GROUP 54C - CAN Bus Diagnostics Table .).

OPERATION



  • The ASTC-ECU contains the power supply circuit (terminal 13) for the motor. ACTS-ECU incorporates a monitor to check if power is supplied to the motor for running.
  • The pump motor switch, which is incorporated in ASTC-ECU, is always off unless the ABS operating or the motor solenoid valve check is activated when the vehicle is started.
  • ASTC-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.
Codes No. C1274 or C1280
  • When the motor relay monitor judges that the motor relay is "ON" while it is "OFF".

PROBABLE CAUSES




  • Fusible link malfunction
  • Damaged wiring harness or connector
  • Malfunction of the hydraulic unit assembly (integrated with ASTC-ECU)

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 Diagnostics Table .). On completion, go to Step 2.

STEP 2. Diagnosis code recheck after resetting CAN bus lines.
(1)Turn the ignition switch to the "ON" position.
(2)Erase the diagnosis code.
(3)Turn the ignition switch to the "LOCK" (OFF) position.
(4)Turn the ignition switch to the "ON" position.
(5)Drive the vehicle at 10 km/h or more.
(6)Check if the diagnosis code is set.
(7)Turn the ignition switch to the "LOCK" (OFF) position.

Q. Are diagnosis codes No.C1266, C1273, C1274 or C1280 set?
Go to Step 3.
The procedure is complete.

STEP 3. Connector check: A-48 ASTC-ECU connector

Q. Is the check result normal?
Go to Step 4.
Repair or replace the damaged component(s). 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-48 ASTC-ECU connector
(1)Removal the fusible link No.22.
(2)Disconnect the A-48 ASTC-ECU connector.
(3)Measure the resistance between the A-48 ASTC-ECU connector terminal No.13 and body earth.
OK: No continuity

Q. Is the check result normal?
Replace the fusible link No.22. Then go to Step 9.
Repair the wiring harness between the fusible link No.22 and A-48 ASTC-ECU connector terminal No.13. Then replace the fusible link No.22. Then go to Step 9.

STEP 6. Voltage measurement at the A-48 ASTC-ECU connector
(1)Disconnect the A-48 ASTC-ECU connector.
(2)Measure the voltage between the A-48 ASTC-ECU connector 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 motor power supply circuit. Repair the wiring harness between the A-48 ASTC-ECU connector terminal No.13 and the fusible link No.22. Then go to Step 9.

STEP 7. Resistance measurement at A-48 ASTC-ECU connector
(1)Disconnect the A-48 ASTC-ECU connector.
(2)Measure the resistance between the A-48 ASTC-ECU connector terminal No.12 and the body earth, and between the terminal No.24 and body earth.
OK: Continuity exists (2 Ω or less)

Q. Is the check result normal?
Go to Step 8.
The open circuit may be present in the earth circuit. Repair the wiring harness between the A-48 ASTC-ECU connector terminal No.12 and the body earth, and between the A-48 ASTC-ECU connector terminal No.24 and the body earth. Then go to Step 9.

STEP 8. Check whether the diagnosis code is reset.
Check again if the diagnosis code is set.
(1)Turn the ignition switch to the "ON" position.
(2)Erase the diagnosis code.
(3)Turn the ignition switch to the "LOCK" (OFF) position.
(4)Turn the ignition switch to the "ON" position.
(5)Drive the vehicle at 10 km/h or more.
(6)Check if the diagnosis code is set.
(7)Turn the ignition switch to the "LOCK" (OFF) position.

Q. Are diagnosis codes No.C1266, C1273, C1274 or C1280 set?
Replace the hydraulic unit assembly (integrated with ASTC-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.
Check again if the diagnosis code is set.
(1)Turn the ignition switch to the "ON" position.
(2)Erase the diagnosis code.
(3)Turn the ignition switch to the "LOCK" (OFF) position.
(4)Turn the ignition switch to the "ON" position.
(5)Drive the vehicle at 10 km/h or more.
(6)Check if the diagnosis code is set.
(7)Turn the ignition switch to the "LOCK" (OFF) position.

Q. Are diagnosis codes No.C1266, C1273, C1274 or C1280 set?
Go to Step 1.
This diagnosis is complete.