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

Lexus RX (RX 350L, RX450h) 2016-2025 Repair Manual / Drivetrain / U881f (automatic Transmission / Transaxle) / Automatic Transaxle System / Transmission Control Switch Circuit

DESCRIPTION

The transmission control switch detects when the shift lever is moved to M.

Moving the shift lever to "+" once selects the next higher gear, and moving the shift lever to "-" once selects the next lower gear.

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

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

PROCEDURE

1.

READ VALUE USING TECHSTREAM (Shift SW Status (S Range))

(a) Connect the Techstream to the DLC3.

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

(c) Turn the Techstream on.

(d) Enter the following menus: Powertrain / Transmission / Data List

(e) Read the Data List according to the display on the Techstream.

Powertrain > Transmission > Data List

Tester Display

Measurement Item

Range

Normal Condition

Diagnostic Note

Shift SW Status (S Range)

Sport (M) mode select switch status

ON or OFF
  • ON: Shift lever in M, "+" or "-"
  • OFF: Shift lever not in M, "+" or "-"

-
Powertrain > Transmission > Data List

Tester Display

Shift SW Status (S Range)

Result

Proceed to

Data List values are normal

A

Data List values are not normal

B
B

GO TO STEP 6

A

2.

READ VALUE USING TECHSTREAM (SPORT SHIFT UP SW AND SPORT SHIFT DOWN SW)

(a) Connect the Techstream to the DLC3.

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

(c) Turn the Techstream on.

(d) Enter the following menus: Powertrain / Engine / Data List

(e) Read the Data List according to the display on the Techstream.

Powertrain > Engine > Data List

Tester Display

Measurement Item

Range

Normal Condition

Diagnostic Note

Sport Shift Up SW

Sport shift up switch status

ON or OFF
  • ON: Shift lever held in "+" or "+" shift paddle switch pulled
  • OFF: Shift lever not held in "+" and "+" shift paddle switch released

-

Sport Shift Down SW

Sport shift down switch status

ON or OFF
  • ON: Shift lever held in "-" or "-" shift paddle switch pulled
  • OFF: Shift lever not held in "-" and "-" shift paddle switch released

-
Powertrain > Engine > Data List

Tester Display

Sport Shift Up SW

Sport Shift Down SW

Result

Proceed to

Data List values are normal

A

Data List values are not normal

B
A

PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE

B

3.

INSPECT TRANSMISSION CONTROL SWITCH (TRANSMISSION FLOOR SHIFT ASSEMBLY)

(a) Disconnect the J21 transmission control switch connector.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

3 (SFTU) - 2 (E)

Shift lever held in "+" (Up shift)

Below 1 Ω

Shift lever not held in "+" (Up shift)

10 kΩ or higher

1 (SFTD) - 2 (E)

Shift lever held in "-" (Down shift)

Below 1 Ω

Shift lever not held in "-" (Down shift)

10 kΩ or higher

*a

Component without harness connected

(Transmission Control Switch (Transmission Floor Shift Assembly))
NG

REPLACE TRANSMISSION FLOOR SHIFT ASSEMBLY (TRANSMISSION CONTROL SWITCH)

OK

4.

CHECK HARNESS AND CONNECTOR (TRANSMISSION CONTROL SWITCH - BODY GROUND)

(a) Disconnect the J21 transmission control switch connector.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

J21-2 (E) - Body ground

Always

Below 1 Ω
NG

REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

5.

CHECK HARNESS AND CONNECTOR (TRANSMISSION CONTROL SWITCH - ECM)

(a) Connect the J21 transmission floor shift assembly (transmission control switch) connector.

(b) Disconnect the A37 ECM connector.

(c) Disconnect the spiral cable sub-assembly connector.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

A37-38 (SFTU) - Body ground

Shift lever held in "+" (Up shift)

Below 1 Ω

Shift lever not held in "+" (Up shift)

10 kΩ or higher

A37-37 (SFTD) - Body ground

Shift lever held in "-" (Down shift)

Below 1 Ω

Shift lever not held in "-" (Down shift)

10 kΩ or higher
OK

PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR (TRANSMISSION CONTROL SWITCH - ECM)

6.

INSPECT TRANSMISSION CONTROL SWITCH (TRANSMISSION FLOOR SHIFT ASSEMBLY)

(a) Disconnect the J21 transmission control switch connector.

*a

Component without harness connected

(Transmission Control Switch (Transmission Floor Shift Assembly))

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

4 (IG) - 5 (S)

Shift lever in M, "+" or "-"

Below 1 Ω

Shift lever not in M, "+" or "-"

10 kΩ or higher
NG

REPLACE TRANSMISSION FLOOR SHIFT ASSEMBLY (TRANSMISSION CONTROL SWITCH)

OK

7.

CHECK HARNESS AND CONNECTOR (TRANSMISSION CONTROL SWITCH (POWER SOURCE))

(a) Disconnect the J21 transmission control switch 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

Condition

Specified Condition

J21-4 (IG) - Body ground

Engine switch on (IG)

11 to 14 V
NG

REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

8.

CHECK HARNESS AND CONNECTOR (TRANSMISSION CONTROL SWITCH - ECM)

(a) Disconnect the J21 transmission control switch connector.

(b) Disconnect the A37 ECM connector.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

J21-5 (S) - A37-17 (S)

Always

Below 1 Ω

J21-5 (S) or A37-17 (S) - Body ground and other terminals

Always

10 kΩ or higher
OK

PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR
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