Wiper System / Washer System (Diagnostics & Circuit Tests): Overview Lexus CT I

SYSTEM DESCRIPTION

1. AUTO WIPER SYSTEM General The auto wiper system controls the wiper timing in accordance with the amount of raindrops that strike the windshield when the wiper switch is in AUTO. The windshield wiper relay assembly controls the timing based on the signal from the rain sensor.
2. HEADLIGHT CLEANER SYSTEM General The headlight cleaner system operates when the headlight cleaner switch is pushed ON. The headlight cleaner system also operates when the front washer switch is first operated with the headlights on.

DESCRIPTION

The windshield wiper relay assembly controls the windshield wiper motor assembly.

Scheme 139

This circuit detects the state of the windshield wiper switch assembly (front wiper switch and front washer switch) and sends it to the windshield wiper relay assembly.

Scheme 140

Scheme 141

1. INSPECT WINDSHIELD WIPER SWITCH ASSEMBLY Remove the windshield wiper switch assembly. Refer to «REMOVAL»(ref-568751-S23665000602013072300000) . Measure the resistance according to the value(s) in the table below. Standard Resistance Front Washer Switch Adjusting Ring*1 FRONT WIPER SWITCH Tester Connection Switch Condition Specified Condition H27-3 (+1) - H27-1 (+S) OFF Below 1 ohms H27-3 (+1) - H27-2 (+B) MIST LO H27-2 (+B) - H27-4 (+2) HI H27-9 (AUTO) - H27-10 (E) AUTO*1 Tester Connection Switch Condition Specified Condition H28-2 (EW) - H28-3 (WF) ON Below 1 ohms OFF 10 kohms or higher Tester Connection Condition Specified Condition H27-7 (VR1) - H27-8 (VR2) Adjusting ring changed from (+) side to (-) side 0 to 2.7 kohms *1: w/ Rain Sensor TEXT IN ILLUSTRATION *a Component without harness connected (Windshield Wiper Switch Assembly) NG --> See step 3 OK: Go to next step
2. CHECK HARNESS AND CONNECTOR (WIPER SWITCH - WIPER RELAY AND BODY GROUND) Disconnect the H28 and H27 windshield wiper switch assembly connectors. Disconnect the H75 windshield wiper relay assembly connector. Measure the resistance according to the value(s) in the table below. Standard Resistance Tester Connection Condition Specified Condition H27-2 (+B) - H75-12 (IG) Always Below 1 ohms H27-2 (+B) - Body ground Always 10 kohms or higher H27-3 (+1) - H75-1 (+2S) Always Below 1 ohms H27-3 (+1) - Body ground Always 10 kohms or higher H27-4 (+2) - H75-3 (+2) Always Below 1 ohms H27-4 (+2) - Body ground Always 10 kohms or higher H27-1 (+S) - H75-11 (+SSW) Always Below 1 ohms H27-1 (+S) - Body ground Always 10 kohms or higher H27-9 (AUTO)*1 - H75-17 (C1) Always Below 1 ohms H27-9 (AUTO)*1 - Body ground Always 10 kohms or higher H27-10 (E) - H75-16 (CO) Always Below 1 ohms H27-10 (E) - Body ground Always 10 kohms or higher H27-7 (VR1)*1 - H75-7 (VR1) Always Below 1 ohms H27-7 (VR1)*1 - Body ground Always 10 kohms or higher H27-8 (VR2)*1 - H75-6 (VR2) Always Below 1 ohms H27-8 (VR2)*1 - Body ground Always 10 kohms or higher H28-3 (WF) - H75-4 (W) Always Below 1 ohms H28-3 (WF) - Body ground Always 10 kohms or higher H28-2 (EW) - Body ground Always Below 1 ohms *1: w/ Rain Sensor NG --> REPAIR OR REPLACE HARNESS OR CONNECTOR OK --> See step 4
3. REPLACE WINDSHIELD WIPER SWITCH ASSEMBLY. Refer to «REMOVAL»(ref-568751-S23665000602013072300000)
4. PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE. Refer to «PROBLEM SYMPTOMS TABLE»(ref-568780-S02140739752013072300000)

The windshield wiper relay assembly receives a signal from the rain sensor to control the auto wiper system.

Scheme 142

Scheme 143

Scheme 144

1. CHECK HARNESS AND CONNECTOR (WINDSHIELD WIPER RELAY ASSEMBLY - RAIN SENSOR) Disconnect the H75 windshield wiper relay assembly connector. Disconnect the T7 rain sensor connector. Measure the resistance according to the value(s) in the table below. Standard Resistance Tester Connection Condition Specified Condition H75-8 (SIG) - T7-4 (SIG) Always Below 1 ohms T7-4 (SIG) - Body ground Always 10 kohms or higher H75-14 (PA1) - T7-3 (AUTO) Always Below 1 ohms T7-3 (AUTO) - Body ground Always 10 kohms or higher H75-25 (E) - T7-1 (ES) Always Below 1 ohms T7-1 (ES) - Body ground Always 10 kohms or higher NG --> REPAIR OR REPLACE HARNESS OR CONNECTOR OK: Go to next step
2. INSPECT WINDSHIELD WIPER RELAY ASSEMBLY Reconnect the H75 windshield wiper relay assembly connector. Measure the voltage according to the value(s) in the table below. Standard Voltage Tester Connection Condition Specified Condition H75-8 (SIG) - H75-25 (E) Power switch on (IG) 7.5 to 8.5 V TEXT IN ILLUSTRATION *a Component with harness connected (Windshield Wiper Relay Assembly) NG --> See step 6 OK: Go to next step
3. INSPECT RAIN SENSOR Reconnect the T7 rain sensor connector. Connect an oscilloscope to the rain sensor connector. Check for pulses. OK Tester Connection Condition Specified Condition T7-3 (AUTO) - T7-1 (ES) Power switch on (IG) Pulse generation TEXT IN ILLUSTRATION *a Component with harness connected (Rain Sensor) NG --> See step 5 OK --> See step 4
4. PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE. Refer to «PROBLEM SYMPTOMS TABLE»(ref-568780-S02140739752013072300000)
5. REPLACE RAIN SENSOR. Refer to «REMOVAL»(ref-568751-S14020132272013072300000)
6. REPLACE WINDSHIELD WIPER RELAY ASSEMBLY. Refer to «REMOVAL»(ref-568751-S18041686872013072300000)

The combination meter assembly receives washer fluid level warning switch condition (on or off) information to control the washer fluid level warning system.

Scheme 145

Scheme 146

1. INSPECT LEVEL WARNING SWITCH ASSEMBLY HINT: The following check should be performed with the windshield washer motor and pump installed to the washer jar. Fill the washer jar with washer fluid. Measure the resistance according to the value(s) in the table below. Standard Resistance Tester Connection Condition Specified Condition 1 (S) - 2 (E) Fluid volume is more than 800 ml 10 kohms or higher 1 (S) - 2 (E) Fluid volume is less than 600 ml Below 1 ohms TEXT IN ILLUSTRATION *a Component without harness connected (Level Warning Switch Assembly) NG --> See step 4 OK: Go to next step
2. CHECK HARNESS AND CONNECTOR (LEVEL WARNING SWITCH - COMBINATION METER AND BODY GROUND) Disconnect the H19 combination meter assembly connector. Measure the resistance according to the value(s) in the table below. Standard Resistance Tester Connection Condition Specified Condition H19-7 (WLVL) - A37-1 (S) Always Below 1 ohms A37-2 (E) - Body ground Always Below 1 ohms H19-7 (WLVL) - Body ground Always 10 kohms or higher NG --> REPAIR OR REPLACE HARNESS OR CONNECTOR OK --> See step 3
3. PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE. Refer to «PROBLEM SYMPTOMS TABLE»(ref-568780-S02140739752013072300000)
4. REPLACE LEVEL WARNING SWITCH ASSEMBLY. Refer to «REMOVAL»(ref-568751-S00345937792013072300000)

The windshield wiper relay assembly receives a vehicle speed signal from the combination meter assembly to control the automatic windshield wiper system.

A voltage of 12 V or 5 V is output from the combination meter assembly and then input to the skid control ECU.

A voltage of 12 V or 5 V is output from each ECU or relay and then input to the combination meter assembly.

The signal is changed to a pulse signal at the transistor in the combination meter assembly.

Each ECU controls the respective system based on the pulse signal.

If a short occurs in any of the ECUs or in the wire harness connected to an ECU, all systems in the diagram below will not operate normally.

Scheme 147

Scheme 148

1. INSPECT COMBINATION METER ASSEMBLY (SPEED SENSOR SIGNAL) Check the output waveform. Remove the combination meter assembly with the connector still connected. Connect an oscilloscope to terminal H19-40 (+S) and body ground. Turn the power switch on (IG). Turn a wheel slowly. Check the signal waveform according to the condition(s) in the table below. Item Condition Tool setting 5 V/DIV., 20 ms./DIV. Vehicle condition Wheel being rotated OK The waveform is similar to that shown in the illustration. HINT: When the system is functioning normally, one wheel revolution generates 4 pulses. As the vehicle speed increases, the width indicated by (A) in the illustration narrows. TEXT IN ILLUSTRATION *a Component with harness connected (Combination Meter Assembly) NG --> See step 5 OK: Go to next step
2. CHECK HARNESS AND CONNECTOR (WINDSHIELD WIPER RELAY ASSEMBLY - COMBINATION METER) Disconnect the H75 windshield wiper relay assembly connector and H19 combination meter assembly connector. Measure the resistance according to the value(s) in the table below. Standard Resistance Tester Connection Condition Specified Condition H75-19 (SPD) - H19-40 (+S) Always Below 1 ohms NG --> See step 3 OK --> See step 4
3. CHECK HARNESS AND CONNECTOR (WINDSHIELD WIPER RELAY ASSEMBLY - JUNCTION CONNECTOR) Disconnect the H75 windshield wiper relay assembly connector and H117 junction connector. Measure the resistance according to the value(s) in the table below. Standard Resistance Tester Connection Condition Specified Condition H75-19 (SPD) - H117-19 Always Below 1 ohms NG --> REPAIR OR REPLACE HARNESS OR CONNECTOR OK --> See step 5
4. PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE. Refer to «PROBLEM SYMPTOMS TABLE»(ref-568780-S02140739752013072300000)
5. GO TO METER / GAUGE SYSTEM. Refer to «Speed Signal Circuit»(ref-568762-S10347095632013072300000)

This circuit provides power to the windshield wiper relay assembly.

Scheme 149

See also:
• REMOVAL