Lexus RX (RX 350L, RX450h) 2016-2025 Repair Manual: AWD Warning Light Remains ON

Lexus RX (RX 350L, RX450h) 2016-2025 Repair Manual / Drivetrain / Mf1a (transfer / 4wd / Awd) / Dynamic Torque Control Awd System / AWD Warning Light Remains ON

DESCRIPTION

The 4WD ECU assembly is connected to the combination meter assembly via CAN communication.

If the 4WD ECU assembly stores any DTCs which are related to the dynamic torque control AWD system, the master warning light illuminates and the AWD warning message is displayed on the multi-information display in the combination meter assembly.

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

  • Inspect the fuses for circuits related to this system before performing the following inspection procedure.
  • When the 4WD ECU assembly is replaced with a known good one from another vehicle, it is necessary to perform calibration.

    Click here

HINT:

Check the condition of each related circuit connector before troubleshooting.

Click here

PROCEDURE

1.

CHECK FOR DTC (CAN COMMUNICATION SYSTEM AND DYNAMIC TORQUE CONTROL AWD SYSTEM)

(a) Check if CAN communication system DTCs are output.

Click here

(b) Check if the dynamic torque control AWD system DTC is output.

Click here

Chassis > Four Wheel Drive > Trouble Codes

Result

Proceed to

CAN communication DTCs and dynamic control AWD system DTCs are not output

A

CAN communication DTCs are output

B

Dynamic torque control AWD system DTCs are output

C

HINT:

If CAN communication DTCs are output, perform troubleshooting for the CAN communication system first.

B

GO TO CAN COMMUNICATION (HOW TO PROCEED WITH TROUBLESHOOTING)

C

REPAIR CIRCUIT INDICATED BY OUTPUT CODE (DYNAMIC TORQUE CONTROL 4WD SYSTEM)

A

2.

CHECK 4WD ECU ASSEMBLY

(a) Check if the 4WD ECU assembly connector is securely connected.

OK:

The connector is securely connected.

NG

CONNECT CONNECTOR TO ECU CORRECTLY
OK

3.

INSPECT BATTERY

(a) Check the battery voltage.

Standard Voltage:

11 to 14 V

NG

CHECK CHARGING SYSTEM

OK

4.

CHECK HARNESS AND CONNECTOR (IG1 TERMINAL)

(a) Disconnect the R10 4WD ECU assembly connector.

(b) Turn the engine switch on (IG).

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

Standard Voltage:

Tester Connection

Switch Condition

Specified Condition

R10-3 (IG1) - Body ground

Engine switch on (IG)

11 to 14 V
NG

REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

5.

CHECK HARNESS AND CONNECTOR (GND TERMINAL)

(a) Turn the engine switch off.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

R10-4 (GND) - Body ground

Always

Below 1 Ω
NG

REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

6.

READ VALUE USING TECHSTREAM (4WD WARNING LIGHT)

(a) Connect the R10 4WD ECU assembly connector.

(b) Turn the engine switch off.

(c) Connect the Techstream to the DLC3.

(d) Turn the engine switch on (IG).

(e) Turn the Techstream on.

(f) Enter the following menus: Chassis / Four Wheel Drive / Data List.

(g) According to the display on the Techstream, read the Data List.

Chassis > Four Wheel Drive > Data List

Tester Display

Measurement Item

Range

Normal Condition

Diagnostic Note

4WD Warning Light

AWD warning (multi-information display)

OFF or ON

OFF: Warning off

ON: Warning on

-
Chassis > Four Wheel Drive > Data List

Tester Display

4WD Warning Light

(h) Check the Techstream display condition of the 4WD Warning Light.

Result

Proceed to

Display of the Data List remains OFF

A

Display of the Data List remains ON

B
A

GO TO METER / GAUGE SYSTEM (HOW TO PROCEED WITH TROUBLESHOOTING)

B

REPLACE 4WD ECU ASSEMBLY

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