Inspection Procedure G-1
Windshield Wiper and Washer: Windshield Wiper does no not Work at All.NOTE: This troubleshooting requires use of scan tool MB991958 and SWS monitor kit MB991862. For details of how to use the SWS monitor, refer to "How to use SWS monitor." How To Use SWS Monitor
Windshield Wiper Motor Circuit Part 1:
Windshield Wiper Motor Circuit Part 2:
CIRCUIT OPERATION
- The windshield wiper and washer switch sends a signal through the column-ECU (incorporated in the column switch) to the front-ECU. If the column-ECU sends a windshield wiper and washer switch "ON" signal to the front-ECU, the front-ECU turns on the relay (incorporated in the front-ECU), thus causing the windshield wiper and washer motor to be turned on.
- If the SWS communication line is defective, the front-ECU operates windshield wiper motor by using the other communication lines (wiper backup circuit) instead of that line. In this case, the windshield wiper works at low speed regardless of the windshield wiper and washer switch positions ("LO" or "HIGH").
TECHNICAL DESCRIPTION (COMMENT)
If the windshield wiper does not work at all, the windshield wiper motor, column switch (windshield wiper and washer switch) or the front-ECU may be defective.
TROUBLESHOOTING HINTS
- Malfunction of the wiper motor
- Malfunction of the column switch (windshield wiper and washer switch)
- Malfunction of the front-ECU
- Damaged harness wires or connectors
DIAGNOSIS
Required Special Tools:
- MB991223: Test Harness Set
- MB991958: Scan Tool (MUT-III Sub Assembly)
- MB991824: V.C.I.
- MB991827: MUT-III USB cable
- MB991910: Main Harness A
- MB991813: SWS monitor kit
- MB991806: SWS monitor cartridge
- MB991812: SWS monitor harness (for column-ECU)
- MB991822: Probe harness
STEP 1. Use scan tool MB991958 to select "ECU COMM Check" on the SWS monitor display.
Check the following ECUs:
- Column-ECU
- Front-ECU
CAUTION: To prevent damage to scan tool MB991958, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991958. Connect special tool MB991911 before connecting special tool MB991812. Be sure to connect special tool MB991806 after turning on special tool MB991824.
1. Connect the special tool. Refer to "How to connect SWS monitor." How to Connect SWS Monitor
2. Turn the ignition switch to the "LOCK" (OFF) position.
3. Operate scan tool MB991958 according to the procedure below to display "ECU COMM Check."
a. Select "Interactive Diagnosis."
b. Select "System Select."
c. Select "SWS."
d. Select "SWS MONITOR."
e. Select "ECU COMM Check."
4. Scan tool MB991958 should show "OK" on the "ECU COMM Check" menus for both the "COLUMN ECU" and "FRONT ECU" menus.
Q: Are "OK" displayed on the "COLUMN ECU" and "FRONT ECU" menu?
"OK" are displayed for all the items: Go to Step 2.
"NG" is displayed on the "COLUMN ECU" menu: Refer to Inspection Procedure A-2 "Communication with column switch (column-ECU) is impossible."
"NG" is displayed on the "FRONT ECU" menu: Refer to Inspection procedure A-4 "Communication with front-ECU is impossible."
STEP 2. Check the input signal by using "FUNCTION DIAG." menu of the SWS monitor.
Check the input signals from the following switches:
- Ignition switch: ACC
- Windshield wiper switch: INT
1. Operate the MUT-III according to the procedure below to display "F.WIPER INT."
a. Select "Interactive Diagnosis."
b. Select "System select."
c. Select "SWS."
d. Select "SWS MONITOR."
e. Select "Function Diag."
f. Select "WIPER."
g. Select "F.WIPER INT."
2. Check that normal conditions are displayed on the items described in the given table.
Q: Does the scan tool display the items "INT WIPER" and "FRONT ECU ACK" as normal condition?
Normal conditions displayed for all the items: Go to Step 3.
The scan tool does not show the respective normal condition for item "INT WIPER SW": Replace the column switch. Check that the windshield wiper works normally.
The scan tool does not show the respective normal condition for item "FRONT ECU ACK": Replace the front-ECU. Check that the windshield wiper works normally.
STEP 3. Check the windshield wiper motor.
1. Disconnect windshield wiper motor connector A-03.
2. Connect a battery to the windshield wiper motor as shown. Then check the windshield wiper motor operates normally at high and low speeds.
Q: Does the windshield wiper motor operate normally?
YES: Go to Step 4.
NO: Replace the windshield wiper motor. Check that the windshield wiper works normally.
STEP 4. Check at windshield wiper motor connector A-03 to check the windshield wiper motor ground circuit.
1. Disconnect windshield wiper motor connector A-03, and measure at the wiring harness side.
2. Measure the resistance value between terminal 5 and ground.
- The measured value should be 2 ohm or less.
Q: Does the measured resistance value correspond with this range?
YES: Go to Step 7.
NO: Go to Step 5.
STEP 5. Check windshield wiper motor connector A-03 for damage.
Q: Is windshield wiper motor connector A-03 in good condition?
YES: Go to Step 6.
NO: Repair or replace the connector. Refer to Harness Connector Inspection. Check that the windshield wiper works normally.
STEP 6. Check the wiring harness between windshield wiper motor connector A-03 (terminal 5) and ground.
Q: Is the wiring harness between windshield wiper motor connector A-03 (terminal 5) and ground in good condition?
YES: No action to be taken.
NO: Repair the wiring harness. Check that the windshield wiper works normally.
STEP 7. Measure at front-ECU connector A-11X in order to check the ignition switch (IG2) line of power supply system to the front-ECU.
1. Disconnect front-ECU connector A-11X, and measure at the relay box side.
2. Turn the ignition switch to the "ON" position.
3. Measure the voltage between terminal 30 and ground.
- The measured value should be approximately 12 volts (battery positive voltage).
Q: Does the measured voltage correspond with this range?
YES: Replace the front-ECU. Check that the windshield wiper works normally.
NO: Go to Step 8.
STEP 8. Check the front-ECU connector A-11X for damage.
Q: Is front-ECU connector A-11X in good condition?
YES: Go to Step 9.
NO: Repair or replace the connector. Refer to Harness Connector Inspection. Check that the windshield wiper works normally.
STEP 9. Check the wiring harness between front-ECU connector A-11X (terminal 30) and the ignition switch (IG2).
NOTE: Also check intermediate connector C-89, junction block connectors C-111 and C-112. If intermediate connectors C-89 or junction block connector C-111 or C-112 is damaged, repair or replace the connector as described in Harness Connector Inspection.
Q: Is the wiring harness between front-ECU connector A-11X (terminal 30) and the ignition switch (IG2) in good condition?
YES: No action to be taken.
NO: Repair the wiring harness. Check that the windshield wiper works normally.