Code No. U1112: SRS-ECU Time-out
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- If diagnosis code No. U1112 is set in the combination meter, always diagnose the CAN bus lines.
- Whenever the ECU is replaced, ensure that the communication circuit is normal.
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TROUBLE JUDGMENT
The combination meter communicates with the SRS-ECU through CAN bus lines. If it can not receive all the necessary signals from the SRS-ECU, diagnosis code No. U1112 is set.
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 SRS-ECU and the combination meter, the power supply system to the SRS-ECU, the SRS-ECU itself, or the combination meter may be defective.
The M.U.T.-III shows a diagnosis code status as stored.
- Carry out diagnosis with particular emphasis on connector(s) or wiring harness in the CAN bus lines between the SRS-ECU and the combination meter, and the power supply system to the SRS-ECU. For diagnosis procedures, refer to "How to cope with past trouble" (Refer to GROUP 00, How to Use Troubleshooting/Inspection Service Points
).
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For a past trouble, you may not 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 possible cause of the trouble by referring to the diagnosis code, which is set regarding the CAN communication-linked ECUs (Refer to GROUP 54C, Explanation about the M.U.T.-III CAN Bus Diagnostics ).
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| caution |
If the ignition switch is turned to the ON position without starting the engine, the diagnosis code may be set after one minutes. Now code Nos. U1100, U1101, U1102, U1106, U1109 and U1112 will be stored as past troubles in the combination meter.
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PROBABLE CAUSES
- Damaged harness wires and connectors
- Malfunction of SRS-ECU
- Malfunction of combination meter
DIAGNOSIS PROCEDURE
STEP 1. M.U.T.-III CAN bus diagnostics
| warning |
Since the radiator fan rotates during CAN bus line diagnostics, make sure that no one is servicing the engine compartment before diagnosing the CAN bus line. Since the CAN communication stops when diagnosing the CAN bus line, the ETACS-ECU detects the time-out of the engine-ECU, and activates the radiator fan to prevent overheating as fail-safe.
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Use the M.U.T.-III to diagnose the CAN bus lines.
Q.
Is the check result satisfactory?
Go to Step 2.
Repair the CAN bus lines (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 SRS-ECU sets a diagnosis code.
Q.
Is the diagnosis code set?
Diagnose the SRS. Refer to GROUP 52B, Troubleshooting . And then go to Step 3.
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. U1112: SRS-ECU time-out diagnosis code
Q.
Is the diagnosis code set?
Go to Step 4.
Go to Step 5.
STEP 4. Check whether the diagnosis code is reset.
Recheck if the diagnosis code is set.
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(1)Erase the diagnosis code.
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(2)Ignition switch: "LOCK" (OFF) position to "ON" position
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(3)Check if the diagnosis code is set.
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Q.
Is the diagnosis code set?
Replace the SRS-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 combination meter and the SRS-ECU or the combination meter (Refer to GROUP 00, How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction ).
STEP 5. Check whether the diagnosis code is reset.
Recheck if the diagnosis code is set.
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(1)Erase the diagnosis code.
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(2)Ignition switch: "LOCK" (OFF) position to "ON" position
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(3)Check if the diagnosis code is set.
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Q.
Is the diagnosis code set?
After the combination meter is replaced, then perform the variant coding (Refer to GROUP 00, Precautions Before Service - How to Perform Variant Coding ). Perform the variant coding, and then go to Step 6.
A poor connection, open circuit or other intermittent malfunction is present in the CAN bus lines between the combination meter and the SRS-ECU or the combination meter (Refer to GROUP 00, How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction ).
STEP 6. Check whether the diagnosis code is reset.
Recheck if the diagnosis code is set.
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(1)Erase the diagnosis code.
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(2)Ignition switch: "LOCK" (OFF) position to "ON" position
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(3)Check if the diagnosis code is set.
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Q.
Is the diagnosis code set?
Return to Step 1.
The procedure is complete.