Code No.U1073: Bus Off
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If diagnosis code U1073 is set in the combination meter, always diagnose the CAN bus lines.
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Whenever the ECU is replaced, ensure that the communication circuit is normal.
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If the combination meter ceases communicating once (i.e. bus off) and then returns to it, the combination meter will not communicate for three minutes immediately after that point. This three-minute period is called "Penalty mode." Immediately after the combination meter returns to communication, the diagnosis code is set.
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COMMENTS ON TROUBLE SYMPTOM
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The wiring harness wire or connectors may have loose, corroded, or damage terminals, or terminals pushed back in the connector, or the combination meter may be defective.
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- Damaged harness wires and connectors
- Malfunction of combination meter
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STEP 1. M.U.T.-III CAN bus diagnostics
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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 satisfactory?
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 Go to Step 2.
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 Repair the CAN bus lines. (Refer to GROUP 54F, Diagnosis - Can Bus Diagnostics Table  ). Repair the CAN bus line and go to Step 3.
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STEP 2. Check whether the diagnosis code is reset.
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Recheck 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 "ON" position.
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(3)Check if the diagnosis code is set.
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Q.
Is the check result satisfactory?
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If the trouble is solved, it is determined that there is an intermittent malfunction such as poor engaged connector(s) or open circuit (Refer to GROUP 00, How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions ).
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Replace combination meter and then go to Step 3.
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STEP 3. Check whether the diagnosis code is reset.
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Recheck 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 "ON" position.
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(3)Check if the diagnosis code is set.
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Q.
Is the check result satisfactory?
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The procedure is complete.
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Go to Step 1.
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