Diagnostic Procedure

STEP 1. Scan tool CAN bus diagnostics
Using scan tool MB991958, diagnose the CAN bus lines.

Q: Is the check result normal?
1. YES: Go to Step 3.
2. NO: Repair the CAN bus lines. (Refer to TROUBLESHOOTING .) After repairing the CAN bus line, go to STEP 2 below.
STEP 2. Check whether the DTC is reset.
Q: Is DTC No. C1613 set?
1. YES: Go to STEP 3 below.
2. NO: This diagnosis is complete.
STEP 3. Intermediate connector, AWC-ECU connector, AWC switch connector check: C-41, C-46, C-120
Q: Is the check result normal?
1. YES: Go to STEP 4 below.
2. NO: Repair the defective connector. Then go to Step 8.
STEP 4. 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 short circuit (short to power supply).

Q: Is the check result normal?
1. YES: Go to STEP 5 below.
2. NO: Repair the wiring harness. Then go to Step 8.
STEP 5. Scan tool service data
Item No. 89: AWC switch (Refer to SERVICE DATA REFERENCE TABLE .)

Q: Is the check result normal?
1. YES: Go to Step 7.
2. NO: Go to STEP 6 below.
STEP 6. AWC switch single unit check
Check the AWC switch. (Refer to AWC SWITCH CHECK .)

Q: Is the check result normal?
1. YES: Go to STEP 7 below.
2. NO: Replace the AWC switch. (Refer to AWC-ECU .) Then go to Step 8.
STEP 7. Check whether the DTC is reset.
Q: Is DTC No. C1613 set?
1. YES: Replace the AWC-ECU. (Refer to AWC-ECU .) Then go to STEP 8 below.
2. NO: Intermittent malfunction. (Refer to HOW TO COPE WITH INTERMITTENT MALFUNCTION .)
STEP 8. Check whether the DTC is reset.
Q: Is DTC No. C1613 set?
1. YES: Return to Step 1.
2. NO: This diagnosis is complete.