Lexus RX (RX 350L, RX450h) 2016-2024 Repair Manual: EPS Warning Light Circuit

DESCRIPTION

If the power steering ECU assembly detects a malfunction, the power steering ECU assembly stores a DTC and illuminates the EPS warning light.

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

  • If the power steering ECU assembly has been replaced, perform assist map writing and torque sensor zero point calibration.

    Click here

  • Inspect the fuses for circuits related to this system before performing the following procedure.

PROCEDURE

1.

CHECK ASSIST LIMIT RECORD

(a) Using the Techstream, read the Data List item "Assist Limit Record 1".

Chassis > EMPS > Data List

Tester Display

Measurement Item

Range

Normal Condition

Diagnostic Note

Assist Limit Record 1

Information of assist limit that was used in the past or is currently in use (latest history)

Unrec, Mtr Overheat, Pow Vol Low, Pow Vol Low Prevent, Eng Stall, Ready OFF, Mtr Overload, Vhcl Spd Sig Malf, Batt Vol Keep

-

-

Chassis > EMPS > Data List

Tester Display

Assist Limit Record 1

HINT:

For the Data List item "Assist Limit Record 1", each item in the Range is described below.

Range

Description

Mtr Overheat

When the vehicle is stopped or traveling at low speed, and steering operations are performed repeatedly or the steering wheel is turned all the way to the side and held there for a long time, assist may be limited in order to prevent overheating of the power steering motor assembly and power steering ECU assembly.

After 10 minutes elapse with the engine stopped and no steering operations being performed, the system will return to normal.

After recovering from the overheated condition, assist can be performed as usual.

Pow Vol Low

When insufficient battery charge, or battery degradation etc. causes the voltage to temporarily decrease, assist may be stopped.

After the battery condition returns to normal, assist can be performed as usual.

Pow Vol Low Prevent

When insufficient battery charge, or battery degradation etc. causes the voltage to temporarily decrease, assist may be limited.

After the battery condition returns to normal, assist can be performed as usual.

Eng Stall

When the engine stalls, battery charge becomes insufficient, so assist is stopped.

After recovering from the engine stall, assist can be performed as usual.

Ready OFF

After Ready ON, if a malfunction in the HV system etc. causes a return to Ready OFF, the HV battery charge becomes insufficient, so assist is stopped.

After returning to Ready ON state, assist can be performed as usual.

Mtr Overload

When the steering wheel cannot turn, such as when a road wheel is against a curb, if the driver continues to apply force to the steering wheel, current to the motor may be limited to prevent overheating.

When the steering wheel is returned to a neutral position, assist can be performed as usual.

DC-DC Malf

If there is a malfunction in the DC-DC converter, etc., assist may be limited.

After the DC-DC converter returns to normal, assist can be performed as usual.

Vhcl Spd Sig Malf

If the vehicle speed signal is abnormal due to a wheel speed sensor malfunction, etc., assist may be limited.

Batt Vol Keep

When insufficient battery charge, or battery degradation etc. causes the voltage to temporarily decrease, assist may be limited.

After the battery condition returns to normal, assist can be performed as usual.

(b) Based on the "Assist Limit Record 1" information, the following Data List items and the information from the customer interview, explain the situation to the customer.

Chassis > EMPS > Data List

Tester Display

Measurement Item

Range

Normal Condition

Diagnostic Note

Record 1 Key Cycle

Number of times that the engine switch was turned on (IG) before Assist Limit Record 1 was stored

Min.: 0 times

Max.: 65535 times

-

-

Record 1 Key Cycle Elapsed Time

Period of time that elapsed since the engine switch was turned on (IG) before Assist Limit Record 1 was stored

Min.: 0.0 s

Max.: 53687091.1 s

-

-

Chassis > EMPS > Data List

Tester Display

Record 1 Key Cycle

Record 1 Key Cycle Elapsed Time

Result

Proceed to

"Unrec" is displayed

A

Other than Unrec is displayed

B

HINT:

If it is necessary to investigate further into the past, check the "Assist Limit Record 2" and "Assist Limit Record 3" information in the same way as "Assist Limit Record 1".

B

EXPLAIN THE CHECKED "ASSIST LIMIT RECORD 1" TO THE CUSTOMER, CROSS-CHECKING THE DATA LIST ITEMS WITH THE INFORMATION FROM THE CUSTOMER INTERVIEW.

A

2.

CHECK HARNESS AND CONNECTOR

(a) Jiggle the power steering ECU assembly connectors and wire harness up and down, and left and right to check the illumination condition of the EPS warning light in the combination meter assembly.

OK:

The EPS warning light illumination condition does not change.

HINT:

When the EPS warning light is operating properly, it illuminates when the engine switch is turned on (IG) and turns off when the engine is started.

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

3.

CHECK CAN COMMUNICATION SYSTEM

(a) Check for DTCs.

Click here

Result

Proceed to

CAN communication system DTCs are not output.

A

CAN communication system DTCs are output.

B

B

GO TO CAN COMMUNICATION SYSTEM

A

4.

CHECK HARNESS AND CONNECTOR (IG POWER SUPPLY - GROUND)

(a) Disconnect the J5 and J4 power steering ECU assembly connectors.

*a

Front view of wire harness connector

(to Power Steering ECU Assembly)

-

-

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

Standard Voltage:

Tester Connection

Condition

Specified Condition

J4-1 (IG) - Body ground

Engine switch on (IG)

8 to 16 V

J5-1 (PIG) - Body ground

Engine switch on (IG)

9 to 16 V

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

J5-2 (PGND) - Body ground

Always

Below 1 Ω

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

5.

INSPECT COMBINATION METER ASSEMBLY

(a) Connect the J5 and J4 power steering ECU assembly connectors.

(b) Perform the Active Test of the combination meter assembly using the Techstream.

Body Electrical > Combination Meter > Active Test

Tester Display

Indicat. EPS

(c) Check the combination meter assembly.

OK:

The EPS warning light turns on or off in accordance with the Techstream operation.

OK

REPLACE POWER STEERING ECU ASSEMBLY

NG

GO TO METER / GAUGE SYSTEM

    Dtc Check / Clear
    DTC CHECK / CLEAR CHECK DTCs (USING TECHSTREAM) (a) Turn the engine switch off. (b) Connect the Techstream to the DLC3. (c) Turn the engine switch on (IG). (d) Turn the Techstream on. (e) Enter the fo ...

    Fail-safe Chart
    FAIL-SAFE CHART If a problem occurs in the power steering system, the power steering assist will be stopped or the amount of power assist will be decreased to protect the system. Power Steering System ...

    Other materials:

    Lexus RX (RX 350L, RX450h) 2016-2024 Repair Manual > Automatic Transaxle System: Transmission Range Sensor "A" Circuit Open (P070513,P070562)
    DESCRIPTION The park/neutral position switch assembly detects the shift lever position and sends signals to the ECM. DTC No. Detection Item DTC Detection Condition Trouble Area MIL Memory Note P070513 Transmission Range Sensor "A" Circuit Open 1. Diagnosis Condition 2. Malfunc ...

    Lexus RX (RX 350L, RX450h) 2016-2024 Repair Manual > Intake System: System Diagram
    SYSTEM DIAGRAM *1 Throttle Body with Motor Assembly *2 Intake Air Control Valve (for ACIS) *3 Intake Air Control Valve Actuator (for ACIS) *4 ECM *5 Vacuum Switching Valve (for ACIS) - - *a Engine Speed Signal *b from Vacuum Tank ...

    Lexus RX (RX 350L, RX450h) 2016-{YEAR} Owners Manual

    Lexus RX (RX 350L, RX450h) 2016-{YEAR} Repair Manual

    © 2024 Copyright www.lexusrx.net
    0.0139