Last Modified: 04-05-2023 6.11:8.1.0 Doc ID: RM100000000ZY3P
Model Year Start: 2017 Model: Sienna Prod Date Range: [08/2016 -           ]
Title: POWER ASSIST SYSTEMS: POWER STEERING SYSTEM: PS Warning Light Remains ON; 2017 - 2020 MY Sienna [08/2016 -        ]

PS Warning Light Remains ON

DESCRIPTION

If the power steering ECU detects a malfunction, the EPS warning light comes on. At this time, the power steering ECU stores a DTC in its memory.

Also if the battery is not sufficiently charged or the voltage decreases temporarily, the amount of power assist may be reduced and the EPS warning light may come on.

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

  • When the steering column assembly is replaced, perform the assist map writing (See page 2016 - 2020 MY Sienna [12/2015 -        ]; POWER ASSIST SYSTEMS: POWER STEERING SYSTEM: REGISTRATION ).
  • Inspect the fuses for circuits related to this system before performing the following inspection procedure.

PROCEDURE

1.

CHECK DTC OUTPUT

(a) Check for DTCs for power steering system (See page 2016 - 2020 MY Sienna [12/2015 -        ]; POWER ASSIST SYSTEMS: POWER STEERING SYSTEM: DTC CHECK / CLEAR ).

Result

Result

Proceed to

DTCs are not output

A

DTCs are output

B
B

GO TO DTC CHART

A

2.

READ VALUE USING TECHSTREAM (BATTERY VOLTAGE LO RECORD)

(a) Connect the Techstream to the DLC3.

(b) Turn the ignition switch to ON.

(c) Turn the Techstream on.

(d) Enter the following menus: Chassis / EMPS / Data List.

(e) In accordance with the display on the Techstream, read the Data List.

EMPS

Tester Display

Measurement Item/Range

Normal Condition

Diagnostic Note

Battery Voltage Lo Record

Battery voltage reduction history

Minimum: 0 times, Maximum: 65535 times

0 times

-

OK:

"Battery Voltage Lo Record" is 0 times.

NG

GO TO CHARGING SYSTEM

OK

3.

CHECK CAN COMMUNICATION SYSTEM

(a) Check for DTCs of the CAN communication system (See page 2017 MY Sienna [08/2016 - 11/2017]; NETWORKING: CAN COMMUNICATION SYSTEM: DIAGNOSIS SYSTEM 2018 MY Sienna [11/2017 - 08/2018]; NETWORKING: CAN COMMUNICATION SYSTEM: DIAGNOSIS SYSTEM 2019 - 2020 MY Sienna [08/2018 -        ]; NETWORKING: CAN COMMUNICATION SYSTEM: DIAGNOSIS SYSTEM ).

Result

Result

Proceed to

DTCs are not output

A

DTCs are output

B
B

GO TO CAN COMMUNICATION SYSTEM

(See page 2017 MY Sienna [08/2016 - 11/2017]; NETWORKING: CAN COMMUNICATION SYSTEM: HOW TO PROCEED WITH TROUBLESHOOTING 2018 - 2020 MY Sienna [11/2017 -        ]; NETWORKING: CAN COMMUNICATION SYSTEM: HOW TO PROCEED WITH TROUBLESHOOTING )
A

4.

PERFORM ACTIVE TEST USING TECHSTREAM (INDICAT EPS)

(a) Connect the Techstream to the DLC3.

(b) Start the engine.

(c) Turn the Techstream on.

(d) Enter the following menus: Body Electrical / Combination Meter / Active Test.

(e) Check that the EPS warning light operates in accordance with the Active Test.

Combination Meter

Tester Display

Test Part

Control Range

Diagnostic Note

Indicat. EPS

EPS warning light

OFF or ON

Confirm that the vehicle is stopped with the engine idling

OK:

The EPS warning light operation normally.

NG

GO TO METER / GAUGE SYSTEM

OK

5.

CHECK HARNESS AND CONNECTOR (STEERING COLUMN ASSEMBLY - BATTERY AND BODY GROUND)

(a) Disconnect the connector from the steering column assembly (power steering ECU).

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

Standard Voltage:

Tester Connection

Condition

Specified Condition

D36-1 (PIG) - Body ground

Always

11 to 14 V

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

D36-2 (PGND) - Body ground

Always

Below 1 Ω

*a

Front view of wire harness connector:

(to Steering Column Assembly (Power Steering ECU))
NG

REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

6.

CHECK HARNESS AND CONNECTOR (STEERING COLUMN ASSEMBLY - IG POWER SUPPLY)

(a) Turn the ignition switch to ON.

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

Standard Voltage:

Tester Connection

Switch Condition

Specified Condition

D35-5 (IG) - Body ground

Ignition switch ON

11 to 14 V

*a

Front view of wire harness connector:

(to Steering Column Assembly (Power Steering ECU))
OK

REPLACE STEERING COLUMN ASSEMBLY

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR