Code No. C1266:
Motor stuck
Code No. C1271: Motor drive circuit
Code No. C1273: Motor drive
circuit stuck off
Code No. C1281: Motor drive circuit (high voltage)
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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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- Whenever ECU is replaced, ensure that the CAN bus lines are normal.
- When the hydraulic unit (integrated with ASTC-ECU) is replaced, always carry out
the calibration of the steering wheel sensor and the G and yaw rate sensor (Refer to ).
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OPERATION
- The ASTC-ECU contains the power supply circuit (+BM terminal) for
the pump motor. The pump motor is energised by the motor relay, which is incorporated in the
ASTC-ECU.
- The motor relay, which is incorporated in the ASTC-ECU, is always off unless the
motor solenoid valve check is activated when the vehicle is started.
- The ASTC-ECU activates the pump motor by turning on the ECU built-in motor relay
when the ABS/ASTC is working.
DIAGNOSIS CODE SET CONDITIONS
These diagnosis codes will be set under the cases below.
Code No. C1266
Code No. C1271
- This diagnosis code will be set when the electric motor circuit fails.
Code No. C1273
- This diagnosis code will be set when the electric motor relay is stuck off.
Codes No. C1281
- This diagnosis code will be set when the electric motor fail-safe relay is stuck
off.
PROBABLE CAUSES
Current trouble
- Fusible link malfunction
- Battery failure
- Damaged harness wires and connectors
- Malfunction of the hydraulic unit assembly (integrated with ASTC-ECU)
Past trouble
- Carry out diagnosis with particular emphasis on connector(s) or
wiring harness between the power supply circuit (+BM terminal) to the ASTC-ECU motor
or earth circuit (GND1 and GND2 terminals). For diagnosis procedures, refer to How to treat
past trouble (GROUP 00 -
How to Use Troubleshooting/Inspection Service Points ).
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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 Diagnostics 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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(1)Turn the ignition switch to the "ON" position.
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(2)Drive the vehicle at 10 km/h or more.
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(3)Erase the diagnosis code.
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(4)Turn the ignition switch to the "LOCK" (OFF) position.
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(5)Turn the ignition switch to the "ON" position.
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(6)Check that the ABS warning lamp, Brake warning lamp, ASTC indicator lamp and ASTC
OFF indicator lamp goes out.
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(7)Check if the diagnosis code is set.
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(8)Turn the ignition switch to the "LOCK" (OFF) position.
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Q.
Is diagnosis code No. C1266, C1271, C1273 or C1281 set?
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Go to Step 3.
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The procedure is complete.
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STEP 3. Check the battery
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Refer to GROUP 54A -
Battery Test .
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Q.
Is the auxiliary battery normal?
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Go to Step 4.
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Charge or replace the battery. Then go to Step 8.
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STEP 4. Check the fusible link No.4
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Q.
Is the check result normal?
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Go to Step 6.
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Go to Step 5.
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STEP 5. Measure the resistance at the ASTC-ECU connector
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(1)Remove the fusible link No.4.
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(2)Check the ASTC-ECU connector.
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(3)Disconnect the connector and measure at the wiring harness side.
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(4)Measure the resistance between +BM terminal and body earth.
OK: No continuity
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Q.
Is the check result normal?
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Replace the fusible link No.4. Then go to Step 8.
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The power supply circuit may be short. Repair the wiring harness wires or connectors
between the ASTC-ECU connector +BM terminal and the fusible links, or replace the fusible
links. Then go to Step 8.
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STEP 6. Measure the voltage at the ASTC-ECU connector
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(1)Check the ASTC-ECU connector.
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(2)Disconnect the connector and measure at the wiring harness side.
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(3)Measure the voltage between +BM terminal and body earth.
OK: Battery voltage
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Q.
Is the check result normal?
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Go to Step 7.
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The power supply circuit may be open. Repair the wiring harness wires or connectors
between the ASTC-ECU connector +BM terminal and the fusible links. Then go to Step
8.
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STEP 7. Check whether the diagnosis code is set again.
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(1)Turn the ignition switch to the "ON" position.
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(2)Drive the vehicle at 10 km/h or more.
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(3)Erase the diagnosis code.
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(4)Turn the ignition switch to the "LOCK" (OFF) position.
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(5)Turn the ignition switch to the "ON" position.
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(6)Check that the ABS warning lamp, Brake warning lamp, ASTC indicator lamp and ASTC
OFF indicator lamp goes out.
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(7)Check if the diagnosis code is set.
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(8)Turn the ignition switch to the "LOCK" (OFF) position.
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Q.
Is diagnosis code No. C1266, C1271, C1273 or C1281 set?
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Replace the hydraulic unit assembly (integrated with ASTC-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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(1)Turn the ignition switch to the "ON" position.
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(2)Drive the vehicle at 10 km/h or more.
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(3)Erase the diagnosis code.
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(4)Turn the ignition switch to the "LOCK" (OFF) position.
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(5)Turn the ignition switch to the "ON" position.
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(6)Check that the ABS warning lamp, Brake warning lamp, ASTC indicator lamp and ASTC
OFF indicator lamp goes out.
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(7)Check if the diagnosis code is set.
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(8)Turn the ignition switch to the "LOCK" (OFF) position.
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Q.
Is diagnosis code No. C1266, C1271, C1273 or C1281 set?
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Return to Step 1.
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This diagnosis is complete.
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