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

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

DESCRIPTION

When the shift lever is in D, operating the "-" (down shift) shift paddle switch will cause the transaxle to enter fixed range mode which restricts the highest gear. By operating the "+" (up shift) or "-" (down shift) shift paddle switch, the gear can be changed.

When the vehicle is being driven with the shift lever in D (fixed range mode), if the vehicle is stopped or the accelerator pedal is kept steady for a certain period of time with the transaxle in the same gear, the vehicle will change back automatically to normal D position operation.

When the shift lever is in M, it is possible to make use of the highest engine speeds by holding the vehicle in a gear. Gear hold control means that gear shifts will not be performed as long as the "+" (up shift), or "-" (down shift) shift paddle switch is not operated.

WIRING DIAGRAM

PROCEDURE

1.

READ VALUE USING TECHSTREAM (SPORT SHIFT SWITCH STATUS)

(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 "+" (Up shift)
  • OFF: Shift lever not held in "+" (Up shift)

-

Sport Shift Down SW

Sport shift down switch status

ON or OFF
  • ON: Shift lever held in "-" (Down shift)
  • OFF: Shift lever not held in "-" (Down shift)

-
Powertrain > Engine > Data List

Tester Display

Sport Shift Up SW

Sport Shift Down SW

Result

Proceed to

Data List values are not normal

A

Data List values are normal

B
B

CHECK FOR INTERMITTENT PROBLEMS

A

2.

CHECK HARNESS AND CONNECTOR (SHIFT PADDLE SWITCH - ECM)

(a) Disconnect the A37 ECM connector.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

A37-38 (SFTU) - Body ground

"+" (Up shift) shift paddle switch operated and held

Below 2.5 Ω

"+" (Up shift) shift paddle switch not operated

1 MΩ or higher

A37-37 (SFTD) - Body ground

"-" (Down shift) shift paddle switch operated and held

Below 2.5 Ω

"-" (Down shift) shift paddle switch not operated

1 MΩ or higher
OK

PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE

NG

3.

CHECK HARNESS AND CONNECTOR (SPIRAL CABLE SUB-ASSEMBLY - ECM)

(a) Disconnect the J29 spiral cable sub-assembly 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

A37-38 (SFTU) - J29-8 (SUP)

Always

Below 1 Ω

A37-37 (SFTD) - J29-1 (SDN)

Always

Below 1 Ω

A37-38 (SFTU) or J29-8 (SUP) - Body ground

Always

10 kΩ or higher

A37-37 (SFTD) or J29-1 (SDN) - Body ground

Always

10 kΩ or higher
NG

REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

4.

CHECK HARNESS AND CONNECTOR (SPIRAL CABLE SUB-ASSEMBLY - BODY GROUND)

(a) Disconnect the J29 spiral cable sub-assembly connector.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

J29-2 (ECC) - Body ground

Always

Below 1 Ω
NG

REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

5.

INSPECT SPIRAL CABLE SUB-ASSEMBLY

(a) Inspect the spiral cable sub-assembly.

Click here

NG

REPLACE SPIRAL CABLE SUB-ASSEMBLY

OK

6.

INSPECT TRANSMISSION SHIFT SWITCH ASSEMBLY (SHIFT PADDLE SWITCH LH)

(a) Remove the transmission shift switch assembly (shift paddle switch LH).

Click here

*a

Component without harness connected

(Shift Paddle Switch LH (Transmission Shift Switch Assembly))

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

B-1 (SDN) - B-2 (ECC)

"-" (Down shift) shift paddle switch operated and held

Below 2.5 Ω

"-" (Down shift) shift paddle switch not operated

1 MΩ or higher
NG

REPLACE TRANSMISSION SHIFT SWITCH ASSEMBLY (SHIFT PADDLE SWITCH LH)

OK

7.

INSPECT TRANSMISSION SHIFT SWITCH ASSEMBLY (SHIFT PADDLE SWITCH RH)

(a) Remove the transmission shift switch assembly (shift paddle switch RH).

Click here

*a

Component without harness connected

(Shift Paddle Switch RH (Transmission Shift Switch Assembly))

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

A-3 (SUP) - A-2 (ECC)

"+" (Up shift) shift paddle switch operated and held

Below 2.5 Ω

"+" (Up shift) shift paddle switch not operated

1 MΩ or higher
NG

REPLACE TRANSMISSION SHIFT SWITCH ASSEMBLY (SHIFT PADDLE SWITCH RH)

OK

8.

INSPECT NO. 1 SWITCH WIRE

(a) Install the transmission shift switch assembly.

Click here

*a

Front view of wire harness connector

(to Spiral Cable Sub-assembly)

(b) Disconnect the z9 No. 1 switch wire connector from the spiral cable sub-assembly.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

z9-1 (SUP) - z9-4 (ECC)

"+" (Up shift) shift paddle switch operated and held

Below 2.5 Ω

"+" (Up shift) shift paddle switch not operated

1 MΩ or higher

z9-3 (SDN) - z9-4 (ECC)

"-" (Down shift) shift paddle switch operated and held

Below 2.5 Ω

"-" (Down shift) shift paddle switch not operated

1 MΩ or higher
OK

PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE

NG

REPLACE NO. 1 SWITCH WIRE

    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 ...

    Automatic Transaxle Unit
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