Inspection Procedure 14: The back-up lamp switch signal is not received <M/T>.
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Whenever the ECU is replaced, ensure that the input signal circuit is normal.
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COMMENTS ON TROUBLE SYMPTOM
Input signal from the back-up lamp switch is used to operate the HSA system functions below. If the signal is abnormal, these functions will not work normally.
PROBABLE CAUSES
- Malfunction of the back-up lamp switch
- Malfunction of the ETACS-ECU
- Damaged harness wires and connectors
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STEP 1. Check the operation of the back-up lamps.
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Check that the back-up lamps illuminate normally.
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Q.
Is the check result normal?
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Go to Step 2.
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Diagnose the rear combination lamps (Refer to Rear Combination lamp, Symptom procedures 3 ). Then go to Step 5.
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STEP 2. Voltage measurement at ETACS-ECU connector (BACK terminal).
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(1)Disconnect the connector, and measure at the wiring harness side.
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(2)Turn the ignition switch to the "ACC" position.
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(3)Check the voltage between the ETACS-ECU connector (BACK terminal) and body earth. OK:
When the shift lever is at the reverse position: Approx. system voltage When the shift lever is at other than the reverse position: 1V or less
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Q.
Is the check result normal?
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Go to Step 3.
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The power supply circuit may be open or short. Repair the connectors or the wiring harness wires between the ETACS-ECU connector and the back-up lamp switch connector. Then go to Step 5.
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STEP 3. Use M.U.T.-III to confirm a diagnosis code of other system.
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Check if the diagnosis code is set in the ASC-ECU.
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Q.
Is the diagnosis code set?
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Troubleshoot the ASC-ECU diagnosis code (Refer to GROUP 35C - Diagnosis Code Chart ). Then go to Step 5.
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Go to Step 4.
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STEP 4. Retest the system.
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Check if the HSA works with one person on the driver’s seat.
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Q.
Is the check result normal?
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The trouble can be an intermittent malfunction.
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Replace the ETACS-ECU. Then go to Step 5.
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STEP 5. Retest the system.
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Check if the HSA works with one person on the driver’s seat.
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Q.
Is the check result normal?
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This diagnosis is complete.
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Return to Step 2.
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