Code No. U0121
ABS/ASC CAN timeout
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.
- Whenever the ECU is replaced, ensure that the CAN bus lines are normal.
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OPERATION
FCM/LDW/AHB-ECU communicates with the ASC-ECU via the CAN bus lines.
DIAGNOSIS CODE SET CONDITION
This diagnosis code is set when the abnormality below is detected:
- The signal sent from the ASC-ECU cannot be received for a certain period.
PROBABLE CAUSES
- Malfunction of the CAN bus line
- Malfunction of the ASC-ECU power supply circuit
- Malfunction of the ASC-ECU
- Malfunction of the FCM/LDW/AHB-ECU
DIAGNOSIS PROCEDURE
STEP 1. M.U.T.-III CAN bus diagnostics.
Use M.U.T.-III to perform the CAN bus diagnosis.
Q.
Is the check result normal?
Go to Step 2.
Repair the CAN bus lines (Refer to GROUP 54C - Troubleshooting ).
STEP 2. M.U.T.-III other system diagnosis code.
Check if the diagnosis code No. U0121 is set to other ECU.
Q.
Is the diagnosis code set?
Go to Step 3.
Go to Step 4.
STEP 3. Check whether the diagnosis code is set again.
Check again if the diagnosis code is set in the FCM/LDW/AHB-ECU.
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(1)Erase the diagnosis code.
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(2)Turn the ignition switch from "LOCK" (OFF) position to "ON" position.
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(3)Check if diagnosis code is set.
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Q.
Is the diagnosis code set?
Replace the ASC-ECU.
The trouble can be an intermittent malfunction (Refer to GROUP 00 - How
to use Troubleshooting/inspection Service Points - How to Cope with Intermittent Malfunction).
STEP 4. Check whether the diagnosis code is set again.
Check again if the diagnosis code is set in the FCM/LDW/AHB-ECU.
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(1)Erase the diagnosis code.
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(2)Turn the ignition switch from "LOCK" (OFF) position to "ON" position.
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(3)Check if diagnosis code is set.
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Q.
Is the diagnosis code set?
Replace the FCM/LDW/AHB-ECU (Refer to ).
The trouble can be an intermittent malfunction (Refer to GROUP 00 - How
to use Troubleshooting/inspection Service Points - How to Cope with Intermittent Malfunction).