Inspection Procedure 8
INSPECTION PROCEDURE 8: The rain sensitive AUTO wiper function works even though there is no rainfall [Vehicles with lighting control sensor].CAUTION: Whenever ECU is replaced, ensure that the input and output signal circuits are normal.
Raindrops Sensing Wiper Function Control Circuit:
TECHNICAL DESCRIPTION (COMMENT)
The lighting control sensor, the harness connector, or the ETACS-ECU may be defective.
TROUBLESHOOTING HINTS
- Malfunction of the lighting control sensor
- Malfunction of ETACS-ECU
- Damaged wiring harness and connectors
DIAGNOSIS
Required Special Tools:
- MB991223: Harness Set
- MB992006: Extra Fine Probe
- MB991958: Scan Tool (M.U.T.-III Sub Assembly)
- MB991824: V.C.I.
- MB991827: M.U.T.-III USB Cable
- MB991910: M.U.T.-III Main Harness A
STEP 1. Lighting control sensor installation surface check
Visual check the presence of scratches or air bubbles (diameter of 5 mm or more) on the windshield to which the lighting control sensor is installed.
Q: Is the check result normal?
YES: Go to Step 2.
NO: Replace the windshield (Refer to Body - Windshield Removal and Installation).
STEP 2. Windshield wiper operation check
Check that the windshield wipers work normally.
Q: Is the check result normal?
YES: Go to Step 3.
NO: Refer to Inspection procedure 3.
STEP 3. Use the scan tool MB991958 to check if an ETACS-related diagnostic trouble code is set.
Connect the scan tool. Refer to Chassis Electrical ETACS, "How to connect the scan tool (M.U.T.-III)".
Q: Is the diagnostic trouble code set?
YES: Diagnose the ETACS-ECU. Refer to Chassis Electrical ETACS, "Diagnostic trouble code chart".
NO: Go to Step 4.
STEP 4.Using scan tool MB991958, read the lighting control sensor diagnostic trouble code.
Check if a lighting control sensor diagnostic trouble code is set. Connect the scan tool. Refer to Chassis Electrical ETACS, "How to connect the scan tool (M.U.T.-III)".
Q: Is the diagnostic trouble code set?
YES: Diagnose the lighting control sensor. [Diagnosis Code: (Refer to Chassis Electrical - Diagnosis Code Chart) or service data.]
NO: Go to Step 5.
STEP 5. Connector check: C-316 ETACS-ECU connector
Q: Is the check result normal?
YES: Go to Step 6.
NO: Repair the damaged connector.
STEP 6. Measure the voltage at the C-316 ETACS-ECU connector.
1. Disconnect the connector, and measure the voltage at the wiring harness side.
2. Measure the voltage between C-316 ETACS-ECU connector terminal No. 1 and body ground.
OK: Battery positive voltage
Q: Is the check result normal?
YES: Replace the Lighting control sensor.
NO: Go to Step 7.
STEP 7. Check the wiring harness between C-316 ETACS-ECU connector terminal No.1 and D-42 lighting control sensor connector terminal No.3.
- Check the input and output lines for open or short circuit.
Q: Is the check result normal?
YES: Intermittent malfunction (Refer to General (Body and Chassis) - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction.)
NO: Repair the wiring harness.