Code No.C1266:
Motor stuck (motor stick or open circuit)
Code No.C1273: Motor drive circuit stuck
off (open circuit)
Code No.C1274: Motor drive circuit stuck on (short circuit)
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- 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
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- Before replacing the ECU, ensure that the communication circuit is normal.
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OPERATION
- ABS-ECU contains the power supply (+BM terminal) circuit 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
These diagnosis codes will be set under the cases below.
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 (+BM terminal) circuit to the ABS-ECU motor
and the earth (GND1 and GND2 terminals) circuit. For diagnosis procedures, refer to How to treat
past trouble (GROUP 00 - How to Cope with Intermittent Malfunctions ).
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STEP 1. M.U.T.-III CAN bus diagnosis
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Use M.U.T.-III to diagnose the CAN bus lines.
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Q.
Is the check result normal?
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 Go to Step 3.
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 Repair the CAN bus lines (Refer to GROUP 54C - CAN Bus Diagnosis Table ).
On completion, go to Step 2.
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STEP 2. Diagnosis code recheck after resetting CAN bus lines
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- Erase the diagnosis code.
- Drive the vehicle at 10 km/h or more.
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Q.
Is diagnosis code No.C1266, C1273 or C1274 set?
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Go to Step 3.
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This diagnosis is complete.
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STEP 3. Check the fusible link
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Q.
Is the check result normal?
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Go to Step 5.
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Go to Step 4.
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STEP 4. Resistance measurement at ABS-ECU connector
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(1)Removal the fusible link.
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(2)Disconnect the ABS-ECU connector.
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(3)Measure the resistance between the +BM terminal and the body earth.
OK: No continuity
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Q.
Is the check result normal?
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Replace the fusible link. Then go to Step 8.
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Repair the defective connector or the harness between the fusible link and ABS-ECU
connector +BM terminal. Then replace the fusible link. Then go to Step 8.
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STEP 5. Voltage measurement at the ABS-ECU connector
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(1)Disconnect the ABS-ECU connector.
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(2)Measure the voltage between the +BM terminal and the body earth.
OK: Battery voltage
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Q.
Is the check result normal?
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Go to Step 6.
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The open circuit may be present in the pump motor power supply circuit. Repair
the defective connector or the wiring harness between the ABS-ECU connector +BM terminal
and the fusible link. Then go to Step 8.
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STEP 6. Resistance measurement at ABS-ECU connector
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(1)Disconnect the ABS-ECU connector.
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(2)Measure the resistance between the GND1 terminal and the body earth, and between
the GND2 terminal and the body earth
OK: Continuity exists (2 Ω or less)
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Q.
Is the check result normal?
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Go to Step 7.
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An open circuit may be present in the earth circuit. Repair the defective connector
or the wiring harness between the ABS-ECU connector GND1 terminal and the body earth, and between
the ABS-ECU connector GND2 terminal and the body earth. Then go to Step 8.
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STEP 7. Check whether the diagnosis code is set again.
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- Erase the diagnosis code.
- Drive the vehicle at 10 km/h or more.
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Q.
Is diagnosis code No.C1266, C1273 or C1274 set?
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Replace the hydraulic unit [(integrated with ABS-ECU) Refer to ].
Then go to Step 8.
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Intermittent malfunction (Refer to GROUP 00 - How to Cope with Intermittent
Malfunctions ).
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STEP 8. Check whether the diagnosis code is set again.
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- Erase the diagnosis code.
- Drive the vehicle at 10 km/h or more.
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Q.
Is diagnosis code No.C1266, C1273 or C1274 set?
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Return to Step 1.
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This diagnosis is complete.
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