Last Modified: 04-05-2023 6.11:8.1.0 Doc ID: RM100000000VKEU
Model Year Start: 2016 Model: Sienna Prod Date Range: [12/2015 -           ]
Title: WIPER / WASHER: WIPER AND WASHER SYSTEM(w/ Rain Sensor): Speed Signal Circuit; 2016 - 2020 MY Sienna [12/2015 -        ]

Speed Signal Circuit

DESCRIPTION

The windshield wiper relay assembly receives a vehicle speed signal from the combination meter 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.

WIRING DIAGRAM

PROCEDURE

1.

CHECK COMBINATION METER SYSTEM

(a) The circuit that sends vehicle speed signals to the combination meter system is inspected in the meter section (See page 2016 MY Sienna [12/2015 - 08/2016]; METER / GAUGE / DISPLAY: METER / GAUGE SYSTEM: Speed Signal Circuit 2017 MY Sienna [08/2016 - 11/2017]; METER / GAUGE / DISPLAY: METER / GAUGE SYSTEM: Speed Signal Circuit 2018 - 2020 MY Sienna [11/2017 -        ]; METER / GAUGE / DISPLAY: METER / GAUGE SYSTEM: Speed Signal Circuit ).

NEXT

2.

CHECK HARNESS AND CONNECTOR (WINDSHIELD WIPER RELAY ASSEMBLY - COMBINATION METER)

(a) Disconnect the D78 windshield wiper relay assembly connector and D145 combination meter connector.

(b) Measure the resistance according to the value(s) in the table below.

Standard Resistance:

Tester Connection

Condition

Specified Condition

D78-19 (SPD) - D145-3 (+S)

Always

Below 1 Ω

D78-19 (SPD) or D145-3 (+S) - Body ground

Always

10 kΩ or higher
NG

REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

3.

INSPECT COMBINATION METER (SPEED SENSOR SIGNAL)

(a) Check the output waveform.

(1) Remove the combination meter assembly with the connector still connected (See page 2016 - 2020 MY Sienna [12/2015 -        ]; METER / GAUGE / DISPLAY: COMBINATION METER: REMOVAL ).

(2) Connect an oscilloscope to terminal D145-3 (+S) and body ground.

(3) Turn the ignition switch to ON.

(4) Turn a wheel slowly.

(5) 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

Driving at approx. 20 km/h (12 mph)

OK:

The waveform is displayed as 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)
OK

PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE

NG

REPLACE COMBINATION METER