Lexus RX (RX 350L, RX450h) 2016-2024 Repair Manual: Right Rear Wheel Speed Sensor Circuit Intermittent (C05121F)

DESCRIPTION

The speed sensor detects wheel speed and sends the appropriate signals to the skid control ECU (brake actuator assembly). These signals are used for brake control.

Speed sensor rotors have rows of alternating N and S magnetic poles, and their magnetic fields change when the rotors turn.

Each speed sensor detects that magnetic change and sends a pulse signal to the skid control ECU (brake actuator assembly).

HINT:

When the connectors between the speed sensor and skid control ECU (brake actuator assembly) are connected, the following waveform is output.

DTC No.	Detection Item	DTC Detection Condition	Trouble Area
C05121F	Right Rear Wheel Speed Sensor Circuit Intermittent	Any of the following is detected: When the +BS terminal voltage is 17.4 V or less, an open in the sensor signal circuit of a malfunctioning area occurs 255 times or more. When the +BS terminal voltage is 17.4 V or less at a vehicle speed of 20 km/h (12 mph) or more, noise occurs in the sensor signals of a malfunctioning wheel 75 times or more within 5 seconds. When the +BS terminal voltage is 17.4 V or less at a vehicle speed of 10 km/h (6 mph) or more, noise occurs once per rotor rotation for 15 seconds or more.	Rear speed sensor RH*1 Rear speed sensor RH (rear axle hub and bearing assembly RH)*2 Sensor installation Rear skid control sensor wire RH No. 1*2 Rear skid control sensor wire RH No. 2*3 Wire harness and connector Rear speed sensor rotor RH (rear axle hub and bearing assembly RH)*2 Skid control ECU (brake actuator assembly)

DTC Detection Conditions: C05121F

		Vehicle Condition
		Pattern 1	Pattern 2	Pattern 3
Diagnosis Condition	When the +BS terminal voltage is 17.4 V or less	○	-	-
	When the +BS terminal voltage is 17.4 V or less at a vehicle speed of 10 km/h (6 mph) or more	-	-	○
	When the +BS terminal voltage is 17.4 V or less at a vehicle speed of 20 km/h (12 mph) or more	-	○	-
Malfunction Status	An open in the sensor signal circuit of a malfunctioning area occurs 255 times or more	○	-	-
	Noise occurs in the sensor signals of a malfunctioning wheel 75 times or more within 5 seconds	-	○	-
	Noise occurs once per rotor rotation	-	-	○
Detection Time		-	-	15 seconds or more
Number of Trips		1 trip	1 trip	1 trip

HINT:

DTC will be output when conditions for any of the patterns in the table above are met.

WIRING DIAGRAM

w/o AVS (for AWD) w/o AVS (for 2WD) w/ AVS (for AWD) w/ AVS (for 2WD)

CAUTION / NOTICE / HINT

PROCEDURE

1.	READ VALUE USING TECHSTREAM (MOMENTARY INTERRUPTION)

(a) Connect the Techstream to the DLC3.

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

(c) Enter the following menus: Chassis / Brake/EPB / Data List.

Chassis > Brake/EPB > Data List

Tester Display	Measurement Item	Range	Normal Condition	Diagnostic Note
RR Speed Sensor Voltage Open	Rear speed sensor RH voltage open detection	Under intermittent / Normal	Under intermittent: Momentary interruption detected Normal: Momentary interruption not detected	-

Chassis > Brake/EPB > Data List

Tester Display
RR Speed Sensor Voltage Open

(d) Select the line graph display.

(e) Check for any momentary interruption in the wire harness and connector.

Click here

OK:

Normal (There are no momentary interruptions.)

NOTICE:

Perform the above inspection before removing the sensor and connector.

NG

GO TO STEP 5

OK

2.	READ VALUE USING TECHSTREAM (RR WHEEL SPEED)

(a) Enter the following menus: Chassis / Brake/EPB / Data List.

Chassis > Brake/EPB > Data List

Tester Display	Measurement Item	Range	Normal Condition	Diagnostic Note
RR Wheel Speed	Rear wheel speed sensor RH reading	Min.: 0.0 km/h (0.0 mph) Max.: 6553.5 km/h (4072 mph)	Vehicle stopped: 0.0 km/h (0.0 mph)	When driving at constant speed: No large fluctuations

Chassis > Brake/EPB > Data List

Tester Display
RR Wheel Speed

(b) Start the engine.

(c) Perform a road test.

(d) Check the speed value output from the speed sensor displayed on the Techstream.

HINT:

Factors that affect the indicated vehicle speed include tire size, tire pressure, and tire wear. The speed indicated on the speedometer has an allowable margin of error. This can be tested using a speedometer tester (calibrated chassis dynamometer). For details about testing and the margin of error, see the reference chart.

Click here

OK:

The speed value output from the speed sensor displayed on the Techstream is similar to the speed indicated on the speedometer.

NG

GO TO STEP 5

OK

3.

CLEAR DTC

(a) Operate the Techstream to clear the codes. Enter the following menus: Chassis / Brake/EPB / Trouble Codes.

Chassis > Brake/EPB > Clear DTCs

(b) Press the DTC clear button.

(c) Turn the engine switch off.

NEXT

4.	RECONFIRM DTC

(a) Start the engine.

(b) Perform a road test.

(c) Read the DTCs following the prompts on the Techstream. Enter the following menus: Chassis / Brake/EPB / Trouble Codes.

Chassis > Brake/EPB > Trouble Codes

(d) Check if the same DTC is output.

Result	Proceed to
DTC C05121F is not output.	A
DTC C05121F is output.	B

A

USE SIMULATION METHOD TO CHECK

B

REPLACE BRAKE ACTUATOR ASSEMBLY

5.	CHECK VEHICLE SPECIFICATION

(a) Check the vehicle specification.

Result	Proceed to
for AWD	A
for 2WD	B

B

GO TO STEP 14

A

6.	CHECK REAR SPEED SENSOR RH INSTALLATION

(a) Turn the engine switch off.

*1 Rear Speed Sensor RH *a Correct *b Incorrect *c 8.5 Nm *d No clearance

(b) Check the rear speed sensor RH installation.

OK:

There is no clearance between the rear speed sensor RH and rear axle carrier sub-assembly RH.

The installation bolt is tightened properly.

Torque

8.5 N*m (87 kgf*cm, 75 in.*lbf)

NG

REINSTALL OR REPLACE REAR SPEED SENSOR RH

OK

7.	CHECK REAR SPEED SENSOR RH AND REAR SPEED SENSOR ROTOR RH (CHECK FOR FOREIGN MATTER)

(a) Remove the rear speed sensor RH and the component with the rear speed sensor rotor RH.

for rear speed sensor RH: Click here

for rear speed sensor rotor RH: Click here

(b) Check the rear speed sensor RH tip and rear speed sensor rotor RH.

OK:

No scratches, oil, or foreign matter on the rear speed sensor RH tip and rear speed sensor rotor RH.

NG

CLEAN OR REPLACE REAR SPEED SENSOR RH OR COMPONENT WITH REAR SENSOR ROTOR RH

OK

8.	CHECK VEHICLE SPECIFICATION

(a) Check the vehicle specification.

Result	Proceed to
w/o AVS	A
w/ AVS	B

B

GO TO STEP 11

A

9.	CHECK HARNESS AND CONNECTOR (REAR SPEED SENSOR RH - BRAKE ACTUATOR ASSEMBLY)

(a) Make sure that there is no looseness at the locking part and the connecting part of the connectors.

OK:

The connector is securely connected.

(b) Disconnect the A41 skid control ECU (brake actuator assembly) connector.

(c) Disconnect the T2 rear speed sensor RH connector.

(d) Check both the connector case and the terminals for deformation and corrosion.

OK:

No deformation or corrosion.

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
T2-2 (RR+) - A41-20 (RR+)	Always	Below 1 Ω
T2-2 (RR+) or A41-20 (RR+) - Body ground	Always	10 kΩ or higher
T2-1 (RR-) - A41-19 (RR-)	Always	Below 1 Ω
T2-1 (RR-) or A41-19 (RR-) - Body ground	Always	10 kΩ or higher

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

10.	INSPECT BRAKE ACTUATOR ASSEMBLY (SENSOR POWER SOURCE CIRCUIT)

(a) Reconnect the A41 skid control ECU (brake actuator assembly) connector.

*a Front view of wire harness connector (to Rear Speed Sensor RH)

(b) Make sure that there is no looseness at the locking part and the connecting part of the connectors.

OK:

The connector is securely connected.

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

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

Standard Voltage:

Tester Connection	Condition	Specified Condition
T2-2 (RR+) - Body ground	Engine switch on (IG)	11 to 14 V

OK

REPLACE REAR SPEED SENSOR RH

NG

REPLACE BRAKE ACTUATOR ASSEMBLY

11.	INSPECT REAR SKID CONTROL SENSOR WIRE RH NO. 2

(a) Make sure that there is no looseness at the locking part and the connecting part of the connectors. OK: The connector is securely connected.

*a Front view of rear skid control sensor wire RH No. 2 *b (to Sensor Side Connector) *c (to Vehicle Side Connector)

(b) Disconnect the z22 and T7 rear skid control sensor wire RH No. 2 connector.

(c) Check both the connector case and the terminals for deformation and corrosion.

OK:

No deformation or corrosion.

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
z22-1 (RR+) - T7-2 (RR+)	Always	Below 1 Ω
z22-1 (RR+) or T7-2 (RR+) - Body ground and other terminals	Always	10 kΩ or higher
z22-3 (RR-) - T7-1 (RR-)	Always	Below 1 Ω
z22-3 (RR-) or T7-1 (RR-) - Body ground and other terminals	Always	10 kΩ or higher

NG

REPLACE REAR SKID CONTROL SENSOR WIRE RH NO. 2

OK

12.	INSPECT HARNESS AND CONNECTOR (REAR SKID CONTROL SENSOR WIRE RH NO. 2 - BRAKE ACTUATOR ASSEMBLY)

(a) Make sure that there is no looseness at the locking part and the connecting part of the connectors.

OK:

The connector is securely connected.

(b) Disconnect the A41 skid control ECU (brake actuator assembly) connector.

(c) Check both the connector case and the terminals for deformation and corrosion.

OK:

No deformation or corrosion.

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
T7-2 (RR+) - A41-20 (RR+)	Always	Below 1 Ω
T7-2 (RR+) or A41-20 (RR+) - Body ground	Always	10 kΩ or higher
T7-1 (RR-) - A41-19 (RR-)	Always	Below 1 Ω
T7-1 (RR-) or A41-19 (RR-) - Body ground	Always	10 kΩ or higher

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

13.	INSPECT BRAKE ACTUATOR ASSEMBLY (SENSOR POWER SOURCE CIRCUIT)

(a) Reconnect the A41 skid control ECU (brake actuator assembly) connector.

*a Front view of rear skid control sensor wire RH No. 2 (to Rear Speed Sensor RH)

(b) Reconnect the T7 rear skid control sensor wire RH No. 2 connector.

(c) Make sure that there is no looseness at the locking part and the connecting part of the connectors.

OK:

The connector is securely connected.

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

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

Standard Voltage:

Tester Connection	Condition	Specified Condition
z22-1 (RR+) - Body ground	Engine switch on (IG)	11 to 14 V

OK

REPLACE REAR SPEED SENSOR RH

NG

REPLACE BRAKE ACTUATOR ASSEMBLY

14.	CHECK REAR SPEED SENSOR RH INSTALLATION

(a) Turn the engine switch off.

*a Correct *b Incorrect *c No clearance

(b) Check the rear speed sensor RH installation.

OK:

There is no clearance between the rear speed sensor RH and the rear axle hub and bearing assembly RH.

HINT:

The rear speed sensor rotor RH and rear speed sensor RH are incorporated into the rear axle hub and bearing assembly RH.

If the rear speed sensor rotor RH needs to be replaced, replace the rear axle hub and bearing assembly RH with rear speed sensor RH.

NG

REPLACE REAR AXLE HUB AND BEARING ASSEMBLY RH

OK

15.	CHECK VEHICLE SPECIFICATION

(a) Check the vehicle specification.

Result	Proceed to
w/o AVS	A
w/ AVS	B

B

GO TO STEP 19

A

16.	INSPECT REAR SKID CONTROL SENSOR WIRE RH NO. 1

(a) Make sure that there is no looseness at the locking part and the connecting part of the connectors. OK: The connector is securely connected.

*a Front view of rear skid control sensor wire RH No. 1 *b (to Sensor Side Connector) *c (to Vehicle Side Connector)

(b) Disconnect the j1 and Tj1 rear skid control sensor wire RH No. 1 connector.

(c) Check both the connector case and the terminals for deformation and corrosion.

OK:

No deformation or corrosion.

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
j1-2 (RR+) - Tj1-2 (RR+)	Always	Below 1 Ω
j1-2 (RR+) or Tj1-2 (RR+) - Body ground and other terminals	Always	10 kΩ or higher
j1-1 (RR-) - Tj1-1 (RR-)	Always	Below 1 Ω
j1-1 (RR-) or Tj1-1 (RR-) - Body ground and other terminals	Always	10 kΩ or higher

NG

REPLACE REAR SKID CONTROL SENSOR WIRE RH NO. 1

OK

17.	CHECK HARNESS AND CONNECTOR (REAR SKID CONTROL SENSOR WIRE RH NO. 1 - BRAKE ACTUATOR ASSEMBLY)

(a) Make sure that there is no looseness at the locking part and the connecting part of the connectors.

OK:

The connector is securely connected.

(b) Disconnect the A41 skid control ECU (brake actuator assembly) connector.

(c) Check both the connector case and the terminals for deformation and corrosion.

OK:

No deformation or corrosion.

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
Tj1-2 (RR+) - A41-20 (RR+)	Always	Below 1 Ω
Tj1-2 (RR+) or A41-20 (RR+) - Body ground	Always	10 kΩ or higher
Tj1-1 (RR-) - A41-19 (RR-)	Always	Below 1 Ω
Tj1-1 (RR-) or A41-19 (RR-) - Body ground	Always	10 kΩ or higher

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

18.	INSPECT BRAKE ACTUATOR ASSEMBLY (SENSOR POWER SOURCE CIRCUIT)

(a) Reconnect the A41 skid control ECU (brake actuator assembly) connector.

*a Front view of rear skid control sensor wire RH No. 1 (to Rear Speed Sensor RH (Rear Axle Hub and Bearing Assembly RH))

(b) Reconnect the Tj1 rear skid control sensor wire RH No. 1 connector.

(c) Make sure that there is no looseness at the locking part and the connecting part of the connectors.

OK:

The connector is securely connected.

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

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

Standard Voltage:

Tester Connection	Condition	Specified Condition
j1-2 (RR+) - Body ground	Engine switch on (IG)	11 to 14 V

HINT:

The rear speed sensor RH is incorporated into the rear axle hub and bearing assembly RH.

If the rear speed sensor RH needs to be replaced, replace the rear axle hub and bearing assembly RH.

OK

REPLACE REAR AXLE HUB AND BEARING ASSEMBLY RH

NG

REPLACE BRAKE ACTUATOR ASSEMBLY

19.	INSPECT REAR SKID CONTROL SENSOR WIRE RH NO. 1

(a) Turn the engine switch off.

*a Front view of rear skid control sensor wire RH No. 1 *b (to Sensor Side Connector) *c (to Vehicle Side Connector)

(b) Make sure that there is no looseness at the locking part and the connecting part of the connectors.

OK:

The connector is securely connected.

(c) Disconnect the j1 and j5 rear skid control sensor wire RH No. 1 connector.

(d) Check both the connector case and the terminals for deformation and corrosion.

OK:

No deformation or corrosion.

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
j1-2 (RR+) - j5-1 (RR+)	Always	Below 1 Ω
j1-2 (RR+) or j5-1 (RR+) - Body ground and other terminals	Always	10 kΩ or higher
j1-1 (RR-) - j5-3 (RR-)	Always	Below 1 Ω
j1-1 (RR-) or j5-3 (RR-) - Body ground and other terminals	Always	10 kΩ or higher

NG

REPLACE REAR SKID CONTROL SENSOR WIRE RH NO. 1

OK

20.	INSPECT REAR SKID CONTROL SENSOR WIRE RH NO. 2

(a) Make sure that there is no looseness at the locking part and the connecting part of the connectors. OK: The connector is securely connected.

*a Front view of rear skid control sensor wire RH No. 2 *b (to Sensor Side Connector) *c (to Vehicle Side Connector)

(b) Disconnect the T7 rear skid control sensor wire RH No. 2 connector.

(c) Check both the connector case and the terminals for deformation and corrosion.

OK:

No deformation or corrosion.

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
j5-1 (RR+) - T7-2 (RR+)	Always	Below 1 Ω
j5-1 (RR+) or T7-2 (RR+) - Body ground and other terminals	Always	10 kΩ or higher
j5-3 (RR-) - T7-1 (RR-)	Always	Below 1 Ω
j5-3 (RR-) or T7-1 (RR-) - Body ground and other terminals	Always	10 kΩ or higher

NG

REPLACE REAR SKID CONTROL SENSOR WIRE RH NO. 2

OK

21.	CHECK HARNESS AND CONNECTOR (REAR SKID CONTROL SENSOR WIRE RH NO. 2 - BRAKE ACTUATOR ASSEMBLY)

(a) Make sure that there is no looseness at the locking part and the connecting part of the connectors.

OK:

The connector is securely connected.

(b) Disconnect the A41 skid control ECU (brake actuator assembly) connector.

(c) Check both the connector case and the terminals for deformation and corrosion.

OK:

No deformation or corrosion.

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
T7-2 (RR+) - A41-20 (RR+)	Always	Below 1 Ω
T7-2 (RR+) or A41-20 (RR+) - Body ground	Always	10 kΩ or higher
T7-1 (RR-) - A41-19 (RR-)	Always	Below 1 Ω
T7-1 (RR-) or A41-19 (RR-) - Body ground	Always	10 kΩ or higher

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

22.	INSPECT BRAKE ACTUATOR ASSEMBLY (SENSOR POWER SOURCE CIRCUIT)

(a) Reconnect the A41 skid control ECU (brake actuator assembly) connector.

*a Front view of rear skid control sensor wire RH No. 1 (to Rear Speed Sensor RH (Rear Axle Hub and Bearing Assembly RH))

(b) Reconnect the j5 and T7 rear skid control sensor wire RH No. 2 connector.

(c) Make sure that there is no looseness at the locking part and the connecting part of the connectors.

OK:

The connector is securely connected.

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

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

Standard Voltage:

Tester Connection	Condition	Specified Condition
j1-2 (RR+) - Body ground	Engine switch on (IG)	11 to 14 V

HINT:

The rear speed sensor RH is incorporated into the rear axle hub and bearing assembly RH.

If the rear speed sensor RH needs to be replaced, replace the rear axle hub and bearing assembly RH.

OK

REPLACE REAR AXLE HUB AND BEARING ASSEMBLY RH

NG

REPLACE BRAKE ACTUATOR ASSEMBLY