Lexus RX (RX 350L, RX450h) 2016-2024 Repair Manual: Drive Start Control

DESCRIPTION

The drive start control is controlled by the ECM.

If the ECM determines that the shift lever and accelerator pedal are operated abnormally, engine output is restricted and, when necessary, a warning is displayed on the combination meter assembly.

CAUTION / NOTICE / HINT

HINT:

Even if the accelerator pedal position is maintained, the engine output may increase when driving uphill and decrease when driving downhill. This is due to the drive start control controlling the engine output, and is not a malfunction.

PROCEDURE

1.	SYMPTOM CONFIRMATION

(a) Interview the customer to confirm the problem.

Result	Proceed to
Hunting	A
Hesitation/poor acceleration	B

B

GO TO STEP 8

A

2.	PAST ACTIVATION CONFIRMATION

(a) Check if the customer operated the vehicle in a way that would cause the drive start control to operate.

Drive Start Control Activation Conditions

HINT:

Condition 1 (Reverse control)

Activation conditions

Items Controlled

Deactivation Conditions

Condition 2 (Shift control a)

Activation conditions

Items Controlled

Deactivation Conditions

Condition 3 (Shift control b)

Activation conditions

Items Controlled

Deactivation Conditions

HINT:

During reverse control or shift control, engine output is adjusted based on the road gradient and steering angle.

Result	Proceed to
Performed	A
Not performed	B

B

SYSTEM NORMAL (GO TO PROBLEM SYMPTOM TABLE)

A

3.	CHECK DTC OUTPUT

(a) Connect the Techstream to the DLC3.

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

(c) Turn the Techstream on.

(d) Enter the following menus: System Select / Health Check.

(e) Check the DTCs.

Result	Proceed to
DTCs are not output	A
DTCs are output	B

B

GO TO DTC CHART

A

4.	READ VALUE USING TECHSTREAM (FR, FL, RR, RL WHEEL SPEED)

(a) Connect the Techstream to the DLC3.

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

(c) Turn the Techstream on.

(d) Start the engine.

(e) Enter the following menus: Chassis / Brake/EPB / Data List / FR Wheel Speed, FL Wheel Speed, RR Wheel Speed and RL Wheel Speed.

Chassis > Brake/EPB > Data List

Tester Display
FR Wheel Speed
FL Wheel Speed
RR Wheel Speed
RL Wheel Speed

(f) Read the value displayed on the Techstream.

Standard:

Techstream Display	Condition	Specified Condition
FR Wheel Speed FL Wheel Speed RR Wheel Speed RL Wheel Speed	Vehicle stopped, engine running	0 km/h (0 mph)
	Vehicle being driven at constant speed between 16.1 to 64.4 km/h (10 to 40 mph)	No large fluctuations when driving at a constant speed

CAUTION:

When performing a drive test, obey all speed limits and traffic laws.

HINT:

Data can be captured relatively easily by using the snapshot function in the Data List. Confirm the data after performing the drive test.

NG

INSPECT FRONT OR REAR SPEED SENSOR

OK

5.	READ VALUE USING TECHSTREAM (OUTPUT AXIS SPEED)

(a) Connect the Techstream to the DLC3.

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

(c) Turn the Techstream on.

(d) Start the engine.

(e) Enter the following menus: Powertrain / Engine / Data List / Output Axis Speed.

Powertrain > Engine > Data List

Tester Display
Output Axis Speed

(f) Read the value displayed on the Techstream.

Standard:

Techstream Display	Condition	Specified Condition
Output Axis Speed	Vehicle stopped, engine running	0 rpm
	Vehicle being driven at a constant speed of approximately 60 km/h (37 mph)	No large fluctuations when driving at a constant speed

CAUTION:

When performing a drive test, obey all speed limits and traffic laws.

HINT:

Data can be captured relatively easily by using the snapshot function in the Data List. Confirm the data after performing the drive test.

NG

INSPECT TRANSMISSION REVOLUTION SENSOR

OK

6.	READ VALUE USING TECHSTREAM (LATERAL G AND FORWARD AND REARWARD G)

(a) Connect the Techstream to the DLC3.

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

(c) Turn the Techstream on.

(d) Start the engine.

(e) Enter the following menus: Chassis / Brake/EPB / Data List / Lateral G and Forward and Rearward G.

Chassis > Brake/EPB > Data List

Tester Display
Lateral G
Forward and Rearward G

(f) Read the value displayed on the Techstream.

Standard:

Techstream Display	Condition	Specified Condition
Lateral G Forward and Rearward G	During deceleration	Value changes with vehicle speed
	During acceleration	Value changes with vehicle speed

CAUTION:

When performing a drive test, obey all speed limits and traffic laws.

HINT:

Data can be captured relatively easily by using the snapshot function in the Data List. Confirm the data after performing the drive test.

Result	Proceed to
OK	A
NG (for Optitron Meter Type)	B
NG (for TFT Meter Type)	C

B

INSPECT AIRBAG SENSOR ASSEMBLY

C

INSPECT YAW RATE SENSOR ASSEMBLY

A

7.	READ VALUE USING TECHSTREAM (STEERING ANGLE VALUE)

(a) Connect the Techstream to the DLC3.

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

(c) Turn the Techstream on.

(d) Start the engine.

(e) Enter the following menus: Chassis / Brake/EPB / Data List / Steering Angle Value.

Chassis > Brake/EPB > Data List

Tester Display
Steering Angle Value

(f) Read the value displayed on the Techstream.

Standard:

Techstream Display	Condition	Specified Condition
Steering Angle Value	Steering wheel turned left	Value increases with steering wheel operation
	Steering wheel turned right	Value decreases with steering wheel operation

CAUTION:

When performing a drive test, obey all speed limits and traffic laws.

HINT:

Data can be captured relatively easily by using the snapshot function in the Data List. Confirm the data after performing the drive test.

OK

SYSTEM NORMAL (GO TO PROBLEM SYMPTOM TABLE)

NG

INSPECT STEERING SENSOR

8.	PAST ACTIVATION CONFIRMATION

(a) Check if the customer operated the vehicle in a way that would cause the drive start control to operate.

Drive Start Control Activation Conditions

HINT:

Condition 1 (Reverse control)

Activation conditions

Items Controlled

Deactivation Conditions

Condition 2 (Shift control a)

Activation conditions

Items Controlled

Deactivation Conditions

Condition 3 (Shift control b)

Activation conditions

Items Controlled

Deactivation Conditions

HINT:

During reverse control or shift control, engine output is adjusted based on the road gradient and steering angle.

Result	Proceed to
Not performed	A
Performed	B

HINT:

If the customer operated the vehicle in a way which caused the drive start control to operate, explain the operation of the system to the customer and that the operation is not a malfunction.

B

SYSTEM NORMAL

A

9.	CHECK DTC OUTPUT

(a) Connect the Techstream to the DLC3.

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

(c) Turn the Techstream on.

(d) Enter the following menus: System Select / Health Check.

(e) Check the DTCs.

Result	Proceed to
DTCs are not output	A
DTCs are output	B

B

GO TO DTC CHART

A

10.	INSPECT PARK/NEUTRAL POSITION SWITCH ASSEMBLY

(a) Inspect the park/neutral position switch assembly.

Result	Proceed to
Normal	A
Abnormal	B

B

REPLACE PARK/NEUTRAL POSITION SWITCH ASSEMBLY

A

11.	READ VALUE USING TECHSTREAM (ACCELERATOR PEDAL POSITION SENSOR)

(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 / Accelerator Position Sensor No.1 Voltage % and Accelerator Position Sensor No.2 Voltage %.

Powertrain > Engine > Data List

Tester Display
Accelerator Position Sensor No.1 Voltage %
Accelerator Position Sensor No.2 Voltage %

(e) Read the value displayed on the Techstream.

OK:

Techstream Display	Condition	Specified Condition
Accelerator Position Sensor No.1 Voltage %	Accelerator Pedal Released → Depressed	Values smoothly change following accelerator pedal operation
Accelerator Position Sensor No.2 Voltage %

HINT:

For numerical values of Accelerator Position Sensor No.1 Voltage % and Accelerator Position Sensor No.2 Voltage %, refer to the Data List.

Click here

OK

SYSTEM NORMAL (GO TO PROBLEM SYMPTOM TABLE)

NG

REPLACE ACCELERATOR PEDAL(W/SENSOR) ROD ASSEMBLY