Inspection Procedure 2: Mode Does Not Change Even When the AWC Switch Is Pressed [Vehicles With Steering Wheel Audio Remote Con

INSPECTION PROCEDURE 2: Mode does not change even when the AWC switch is pressed [Vehicles with steering wheel audio remote control switch]

AWC MODE SELECT SWITCH SYSTEM CIRCUIT
C1613

CAUTION
^ If there is any problem in the CAN bus lines, an incorrect trouble symptom may occur. Prior to this diagnosis, always diagnose the CAN bus lines.
^ Whenever the ECU is replaced, ensure that the CAN bus lines are normal.

COMMENTS ON TROUBLE SYMPTOM
AWC switch or AWC-ECU may have a problem.

PROBABLE CAUSES
^ AWC switch malfunction
^ Malfunction of the ETACS-ECU
^ Malfunction of the combination meter
^ Damaged harness wires and connectors
^ Malfunction of AWC-ECU

DIAGNOSTIC PROCEDURE

STEP 1. Scan tool CAN bus diagnostics
Using scan tool MB991958, diagnose the CAN bus lines.
Q: Is the check result normal?
YES: Go to Step 3.
NO: Repair the CAN bus lines. After repairing the CAN bus line, go to Step 2.

STEP 2. Retest the system.
Q: Is the check result normal?
YES: Intermittent malfunction.
NO: Go to Step 3.

STEP 3. Scan tool service data
Item No. 89: AWC switch (Data List Reference Table)
Q: Is the check result normal?
YES: Go to Step 11.
NO: Go to Step 4.

STEP 4. AWC switch single unit check
Check the AWC switch.(Service and Repair)
Q: Is the check result normal?
YES: Go to Step 5.
NO: Replace the AWC switch. Then go to Step 13.

STEP 5. Measure the voltage at C-120 AWC switch connector.
1) Disconnect the connector, and measure the voltage between terminal No.2 and ground at the harness side.
2) Turn the ignition switch to the "ON" position.
OK: Battery positive voltage
Q: Is the check result normal?
YES: Go to Step 8.
NO: Go to Step 6.

STEP 6. AWC switch connector, ETACS-ECU connector check: C120, C-317
Q: Is the check result normal?
YES: Go to Step 7.
NO: Repair the defective connector. Then go to Step 13.

STEP 7. Check the wiring harness between C-120 AWC switch connector terminal No. 2 and C-317 ETACS-ECU connector terminal No. 5.
Check the wiring harness for open or short circuit (short to ground).
Q: Is the check result normal?
YES: Replace the ETACS-ECU. Then go to Step 12.
NO: Repair the wiring harness. Then go to Step 13.

STEP 8. Voltage measurement at C-46 AWC-ECU connector
1) With C-46 AWC-ECU connector connected, measure the voltage between terminal No. 21 and ground at the harness side.
2) Turn the ignition switch to the "ON" position.
OK: Battery voltage (Press and hold the AWC switch)
OK: 1 V or less (Release the AWC switch)
Q: Is the check result normal?
YES: Go to Step 11.
NO: Go to Step 9.

STEP 9. Intermediate connector, AWC-ECU connector, AWC switch connector check: C-42, C-46, C-120
Q: Is the check result normal?
YES: Go to Step 10.
NO: Repair the defective connector. Then go to Step 13.

STEP 10. Wiring harness check between C-46 AWC-ECU connector terminal No. 21 and C-120 AWC switch connector terminal No. 1
Check the wiring harness for open or short circuit (short to ground).
Q: Is the check result normal?
YES: Replace the AWC-ECU. Then go to Step 13.
NO: Repair the wiring harness. Then go to Step 11.

STEP 11. Scan tool service data
Combination meter item No. F13, F14, F15: Mode display (Service Data)
Q: Is the check result normal?
YES: Go to Step 12.
NO: Replace the combination meter. Then go to Step 12.

STEP 12. Retest the system.
Q: Is the check result normal?
YES: Intermittent malfunction.
NO: Replace the AWC-ECU. Then go to Step 13.

STEP 13. Retest the system.
Q: Is the check result normal?
YES: Return to Step 1.
NO: This diagnosis is complete.