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Diagnosis code 12: Trouble related to the column switch or improper connection with the ETACS-ECU
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|  CAUTION
Whenever the ECU is replaced, ensure that the power supply circuit, the grounding circuit and the communication circuit are normal.
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| COMMENTS ON TROUBLE SYMPTOM
If the column switch ignores the data request signal sent by the ETACS-ECU (three times or more for one second), this diagnosis code will be set. Then, when the column switch observes the request signal for one second, the ECU will stop sending the diagnosis code.
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| POSSIBLE CAUSES
- Malfunction of the column switch
- Malfunction of the ETACS-ECU
- Damaged harness wires and connectors
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| Step 1. Use the MUT-II/III to confirm a diagnosis code. (MUT-II/III diagnosis code)
- Ignition switch: ON
- On completion, check that diagnosis code No.12 is not reset.
Q: Is diagnosis code No.12 set?
YES:
Go to Step 5  .
NO:
Go to Step 2  .
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| Step 2. Connector check: C-310 column switch connector
Q: Is the check result normal?
YES:
Go to Step 3  .
NO:
Repair the defective connector.
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| Step 3. Measure the voltage at C-310 column switch connector.
- Remove the column switch connector, and measure at the wiring harness side.
- Voltage between C-310 column switch connector terminal No.1 and body earth
OK: Battery positive voltage
Q: Is the check result normal?
YES:
Replace the column switch.
NO:
Go to Step 4  .
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| Step 4. Check the wiring harness between C-310 column switch connector terminal No.1 and the battery.
NOTE: Prior to the wiring harness inspection, check intermediate connector C-116, joint connector C-02 and junction block connector C-202 <RH drive vehicles>, and repair if necessary.
- Check the power supply line for open circuit.
Q: Is the check result normal?
YES:
The trouble can be an intermittent malfunction (Refer to GROUP 00 -
How to Cope with Intermittent Malfunction  ).
NO:
Repair the wiring harness.
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| Step 5. Measure the resistance at the C-310 column switch connector.
- Remove the column switch, and measure at the wiring harness side.
- Resistance between C-310 column switch connector terminal No.4 and body earth
OK: 2 Ω
or less
Q: Is the check result normal?
YES:
Go to Step 7  .
NO:
Go to Step 6  .
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| Step 6. Check the wiring harness between C-310 column switch connector terminal No.4 and the body earth.
- Check the earth wires for open circuit.
Q: Is the check result normal?
YES:
The trouble can be an intermittent malfunction (Refer to GROUP 00 -
How to Cope with Intermittent Malfunction  ).
NO:
Repair the wiring harness.
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| Step 7. Connector check: C-219 ETACS-ECU connector
Q: Is the check result normal?
YES:
Go to Step 8  .
NO:
Repair the defective connector.
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| Step 8. Check the wiring harness from C-219 ETACS-ECU connector terminal Nos.59 and 68 to C-310 column switch connector terminal Nos.3 and 2.
NOTE: Prior to the wiring harness inspection, check joint connector C-02, and repair if necessary.
- Check the communication lines for open circuit.
Q: Is the check result normal?
YES:
Go to Step 9  .
NO:
Repair the wiring harness.
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| Step 9. Check whether the diagnosis code is reset.
Replace the column switch, and then check that the diagnosis code is not reset.
- Replace the column switch.
- Ignition switch: ON
- On completion, check that diagnosis code No.12 is not reset.
Q: Is diagnosis code No.12 set?
YES:
Replace the ETACS-ECU.
NO:
The procedure is complete.
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