Code No.U0121
ABS/ASC CAN timeout
JUDGEMENT CRITERIA
With the ignition switch is at ON position, the diagnosis code No. U1190 is not stored
and the diagnosis code No. U1195 is not stored, if the communication with ABS-ECU cannot be established
for 2500 ms or more, the combination meter determines that a problem has occurred.
COMMENTS ON TROUBLE SYMPTOM
The M.U.T.-III shows a diagnosis code status as active.
- Connector(s) or wiring harness in the CAN bus lines between the combination meter
and the ABS-ECU, the power supply circuits to the ABS-ECU itself may be defective.
The M.U.T.-III shows a diagnosis code status as stored.
- If diagnosis code No.U0121 is set as past trouble, carry out diagnosis with particular
emphasis on wiring and connector(s) in the CAN bus lines between the combination meter and the
ABS-ECU, or power supply to the ABS-ECU. For diagnosis procedures, refer to GROUP 00, How to
Use Troubleshooting/Inspection Service Points - How to Treat Past Trouble
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For a past trouble, you cannot find it by the M.U.T.-III CAN bus diagnostics even if there is
any failure in CAN bus lines. In this case, refer to GROUP 00, How to Use Troubleshooting/Inspection
Service Points - How to Cope with Intermittent Malfunctions and
check the CAN bus lines. You can narrow down the probable cause of the trouble by referring
to the diagnosis code, which is set regarding the CAN communication-linked ECUs (Refer to GROUP 54C - CAN
Bus Line Diagnostic Flow ).
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PROBABLE CAUSES
- Malfunction of the combination meter
- Malfunction of the ABS-ECU
- Malfunction of wiring harness or connector
DIAGNOSIS PROCEDURE
STEP 1. M.U.T.-III CAN bus diagnostics
Use the M.U.T.-III to diagnose the CAN bus lines.
Q.
Is the check result normal?
Go to Step 2.
Repair the CAN bus line (Refer to GROUP 54C - Troubleshooting ).
Repair the CAN bus line and go to Step 6.
STEP 2. M.U.T.-III other system diagnosis code
Check that the ABS-ECU sets a diagnosis code.
Q.
Is the diagnosis code set?
Diagnose the ABS-ECU (Refer to GROUP 35B - Troubleshooting ).
Go to Step 3.
STEP 3. M.U.T.-III other system diagnosis code
Check if a diagnosis code, which relates to CAN communication-linked systems below, is
set.
ETACS-ECU
- Code No.U0121: ABS/ASC CAN timeout
Q.
Is the diagnosis code set?
Go to Step 4.
Go to Step 5.
STEP 4. Check whether the diagnosis code is reset.
Check again if the diagnosis code is set to the combination meter.
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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)On completion, check that the diagnosis code is reset.
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Q.
Is the diagnosis code set?
Replace the ABS-ECU and then go to Step 6.
A poor connection, open circuit or other intermittent malfunction is present in
the CAN bus lines between the ABS-ECU and the combination meter (Refer to GROUP 00 - How
to use troubleshooting/Inspection Service Points ).
STEP 5. Check whether the diagnosis code is reset.
Check again if the diagnosis code is set to the combination meter.
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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)On completion, check that the diagnosis code is reset.
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Q.
Is the diagnosis code set?
Replace the combination meter. and then go to Step 6.
A poor connection, open circuit or other intermittent malfunction is present in
the CAN bus lines between the ABS-ECU and the combination meter (Refer to GROUP 00 - How
to use troubleshooting/Inspection Service Points ).
STEP 6. Check whether the diagnosis code is reset.
Recheck if the diagnosis code is set to the combination meter.
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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)On completion, check that the diagnosis code is reset.
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Q.
Is the diagnosis code set?
Return to Step 1.
The procedure is complete.