Code No.U1073: Bus off error
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If diagnosis code No. U1073 is set in the A/C-ECU, diagnose the CAN main bus line.
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Whenever the ECU is replaced, ensure that the communication circuit is normal.
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If the A/C-ECU 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 A/C-ECU may be defective.
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- Damaged harness wires and connectors
- Malfunction of the A/C-ECU
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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 normal?
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Go to Step 2
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Repair the CAN bus lines. (Refer to GROUP 54F - Troubleshooting .) On completion, go to Step 3.
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STEP 2. M.U.T.-III diagnosis code.
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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)Ignition switch: LOCK (OFF) to ON
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(3)Check if the diagnosis code is set.
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Q.
Is the diagnosis code set?
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Replace the A/C-ECU, and then go to Step 3 .
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If a 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 Cope with Intermittent Malfunction ).
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STEP 3. M.U.T.-III diagnosis code
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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)Ignition switch: LOCK (OFF) to ON
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(3)Check if the diagnosis code is set.
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Q.
Is the diagnosis code set?
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Return to Step 1.
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The procedure is complete.
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