Code No. C1550: ECU failure
Code No. C1554: Speed sensor is out of range
Code No. C1555: Steering angle SNS.out of range
Code No. C1556: Detection part abnormality
Code No. C1608: EEPROM fail
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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 - Troubleshooting
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- Whenever ECU is replaced, ensure that the CAN bus lines are normal.
- When the steering wheel sensor is replaced, always carry out calibration to make ASTC-ECU learn the neutral point (Refer to ).
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OPERATION
The steering wheel sensor outputs the steering wheel status to ASTC-ECU via the CAN bus lines.
DIAGNOSIS CODE SET CONDITIONS
Code No. C1550
- When the system detects an abnormal power supply voltage.
- When the system detects an abnormal steering wheel turning speed.
- Failure of a sensor element
Code No. C1554
- When the system detects an extremely high steering wheel turning speed.
Code No. C1555
- When the system detects an abnormal steering wheel angle.
Code No. C1556
- When the system detects an abnormal power supply voltage.
Code No. C1608
- When the system detects malfunction on read or written data.
PROBABLE CAUSES
Current trouble
- The CAN bus line is defective.
- Malfunction of the column switch assembly (Integrated with steering wheel sensor)
Past trouble
- Carry out diagnosis with particular emphasis on wiring harness and connector failures between ASTC-ECU and the wheel speed sensor. 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 the 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 - Troubleshooting ). On completion, go to Step 2.
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STEP 2. Diagnosis code recheck after resetting CAN bus lines
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Q.
Is diagnosis code No. C1550, C1554, C1555, C1556 or C1608 set?
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Go to Step 3.
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This diagnosis is complete.
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STEP 3. Check whether the diagnosis code is set again.
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Check again if the diagnosis code is set.
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(1)Erase the diagnosis code.
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(2)Turn the ignition switch to the "LOCK" (OFF) position.
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(3)Turn the ignition switch to the "ON" position.
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(4)Check if the diagnosis code is set.
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(5)Turn the ignition switch to the "LOCK" (OFF) position.
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Q.
Is diagnosis code No. C1550, C1554, C1555, C1556 or C1608 set?
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Replace the column switch assembly (Integrated with steering wheel sensor) (Refer to GROUP 54A - Column Switch ).
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The trouble can be an intermittent malfunction (Refer to GROUP 00 - How to Cope with Intermittent Malfunction ).
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