INSPECTION
PROCEDURE 11: Heater controller assembly (A/C-ECU) power supply system
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COMMENTS ON TROUBLE SYMPTOM
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If the heater controller assembly (A/C-ECU) is not energised, the power supply
or earth system to the ECU may be defective.
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- Malfunction of the heater controller assembly (A/C-ECU)
- Damaged wiring harness or connectors
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STEP 1. M.U.T.-III other system’s diagnosis code
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Check that the ETACS-ECU has not set a diagnosis code.
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Q.
Is the diagnosis code set?
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Carry out the diagnosis code procedures. Refer to GROUP 54A, ETACS-ECU .
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Go to Step 2.
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STEP 2. Measure the voltage at the heater controller assembly (A/C-ECU)
connector.
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(1)Disconnect the connector, and measure at the wiring harness side.
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(3)Voltage between terminal No. 20 and body earth OK: System voltage
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Q.
Is the check result normal?
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Go to Step 4.
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Go to Step 3.
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STEP 3. Check of open circuit in heater controller assembly (A/C-ECU)
IG1line between ETACS-ECU connector and heater controller assembly (A/C-ECU) connector.
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Q.
Is the check result normal?
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Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection
Service Points - How to Cope with Intermittent Malfunction ).
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Repair the connector(s) or wiring harness.
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STEP 4. Measure the voltage at the heater controller assembly (A/C-ECU)
connector.
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(1)Disconnect the connector, and measure at the wiring harness side.
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(2)Voltage between terminal No. 19 and body earth OK: System voltage
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Q.
Is the check result normal?
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Go to Step 6.
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Go to Step 5.
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STEP 5. Check of open circuit in heater controller assembly (A/C-ECU)
B/UP line between ETACS-ECU connector and heater controller assembly (A/C-ECU) connector.
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Prior to the wiring harness inspection, check joint connector and repair if necessary.
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Q.
Is the check result normal?
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Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection
Service Points - How to Cope with Intermittent Malfunction ).
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Repair the connector(s) or wiring harness.
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STEP 6. Measure the resistance at the heater controller assembly (A/C-ECU)
connector.
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(1)Disconnect the connector, and measure at the wiring harness side.
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(2)Resistance between terminal No. 18 and body earth OK: Continuity exists (2 Ω or less)
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Q.
Is the check result normal?
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Replace the heater controller assembly (A/C-ECU).
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Go to Step 7.
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STEP 7. Check of open circuit in heater controller assembly (A/C-ECU)
E line between heater controller assembly (A/C-ECU) connector and earth J/C (DASH) connector.
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Q.
Is the check result normal?
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Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection
Service Points - How to Cope with Intermittent Malfunction ).
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Repair the connector(s) or wiring harness.
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