Lexus RX (RX 350L, RX450h) 2016-2025 Repair Manual: AWD Control Switch Circuit

DESCRIPTION

The 4WD ECU assembly changes the control mode in response to the "Lock Mode" signal from the AWD lock switch (combination switch assembly).

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

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.

INSPECT AWD LOCK MODE INDICATOR LIGHT

(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 following menus: Chassis / Four Wheel Drive / Active Test

(f) According to the display on the Techstream, perform the Active Test.

Chassis > Four Wheel Drive > Active Test

Tester Display

Measurement Item

Control Range

Diagnostic Note

4WD LOCK Light

AWD lock mode indicator light

Indicator light OFF/ON

Observe the combination meter assembly

(g) When performing the 4WD LOCK Light Active Test, check 4WD LOCK Light in the Data List.

Chassis > Four Wheel Drive > Data List

Tester Display

Measurement Item

Range

Normal Condition

Diagnostic Note

4WD LOCK Light

AWD lock mode indicator light

OFF or ON

OFF: AWD lock mode indicator light off

ON: AWD lock mode indicator light on

-

Chassis > Four Wheel Drive > Active Test

Active Test Display

4WD LOCK Light

Data List Display

4WD LOCK Light

Result

Proceed to

Data List item 4WD LOCK Light changes according to the Active Test

A

Data List item 4WD LOCK Light does not change according to the Active Test

B

B

REPLACE 4WD ECU ASSEMBLY

A

2.

INSPECT COMBINATION SWITCH ASSEMBLY

(a) Turn the engine switch off.

(b) Remove the AWD lock switch (combination switch assembly).

Click here

(c) Inspect the AWD lock switch (combination switch assembly).

Click here

NG

REPLACE COMBINATION SWITCH ASSEMBLY

OK

3.

CHECK HARNESS AND CONNECTOR (COMBINATION SWITCH ASSEMBLY - BODY GROUND)

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

J35-1 (GND) - Body ground

Always

Below 1 Ω

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

4.

CHECK HARNESS AND CONNECTOR (COMBINATION SWITCH ASSEMBLY - 4WD ECU ASSEMBLY)

(a) Reinstall the AWD lock switch (combination switch assembly).

Click here

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

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

Standard Resistance:

Tester Connection

Switch Condition

Specified Condition

R10-10 (4WDS) - Body ground

Switch pressed and held

Below 100 Ω

Switch released

1 MΩ or higher

OK

REPLACE 4WD ECU ASSEMBLY

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

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