Diagnostic Procedure

WARNING: This page is about a different variant/trim than selected.

Required Special Tools:

MB991958 Scan Tool (M.U.T.-III Sub Assembly)
- MB991824: Vehicle Communication Interface (V.C.I.)
- MB991827 M.U.T.-III USB Cable
- MB991910 M.U.T.-III Main Harness A

STEP 1. Check the battery.
Refer to BATTERY TEST .

Q: Is the battery in good condition?
1. YES: Go to Step 2.
2. NO: Charge or replace the battery.
STEP 2. Measure the resistance at B-120 TC-SST-ECU connector.
Disconnect the connector, and measure the resistance between terminal No. 19 and ground at the wiring harness side.

OK: Continuity exists. (2 Ω or less)

Q: Is the check result normal?
1. YES: Go to Step 5.
2. NO: Go to Step 3.
STEP 3. TC-SST-ECU connector check: B-120
Check for the contact with terminals.

Q: Is the check result normal?
1. YES: Go to Step 4.
2. NO: Repair the defective connector.
STEP 4. Check the wiring harness between B-120 TC-SST-ECU connector terminal No. 19 and body ground.
Check the ground line for open circuit.

Q: Is the check result normal?
1. YES: Go to Step 5.
2. NO: Repair the wiring harness.
STEP 5. Measure the voltage at B-120 TC-SST-ECU connector.
Disconnect the connector, and measure the voltage between terminal No. 6 and ground at the wiring harness side.

OK: Battery positive voltage

Q: Is the check result normal?
1. YES: Go to Step 8.
2. NO: Go to Step 6.
STEP 6. Inspection of the intermediate connector and TC-SST-ECU connector: A-54, B-120
Check for the contact with terminals.

Q: Is the check result normal?
1. YES: Go to Step 7.
2. NO: Repair the defective connector.
STEP 7. Check the wiring harness between B-120 TC-SST-ECU connector terminal No. 6 and fusible link No. 36.
Check the power supply line for short or open circuit.

Q: Is the check result normal?
1. YES: Go to Step 8.
2. NO: Repair the wiring harness.
STEP 8. Scan tool diagnostic trouble code
Check the ETACS diagnostic trouble code. (Refer to TROUBLESHOOTING .)

Q: Is the DTC set?
1. YES: Perform the relevant troubleshooting.
2. NO: Go to Step 9.
STEP 9. Measure the voltage at B-120 TC-SST-ECU connector.
1. Disconnect the connector, and measure the voltage between terminal No. 11 and ground at the wiring harness side.
2. Turn the ignition switch to the "ON" position.
  OK: Battery positive voltage
Q: Is the check result normal?
1. YES: Go to Step 12.
2. NO: Go to Step 10.
STEP 10. Inspection of the intermediate connector, TC-SST-ECU connector, J/C (1), and ETACS-ECU connector: A-54, C-128, B-120, C-03, C-317
Check for the contact with terminals.

Q: Is the check result normal?
1. YES: Go to Step 11.
2. NO: Repair the defective connector.
STEP 11. Check the wiring harness between B-120 TC-SST-ECU connector terminal No. 11 and C-317 ETACS-ECU connector terminal No. 5.
Check the power supply line for short or open circuit.

Q: Is the check result normal?
1. YES: Go to Step 12.
2. NO: Repair the wiring harness.
STEP 12. Retest the system.
Q: Does a malfunction take place again?
1. YES: Replace the mechatronic assembly. (Refer to << A >> MECHATRONIC ASSEMBLY REMOVAL .)
2. NO: Intermittent malfunction. (Refer to HOW TO COPE WITH INTERMITTENT MALFUNCTION .)