Lexus NX: Low Output Signal of Front Speed Sensor RH (C1271,C1272,C1464,C1465)

DESCRIPTION

Each speed sensor detects the wheel speed and sends the signals to the skid control ECU (brake booster with master cylinder assembly). These signals are used for ABS control.

DTCs C1271 and C1272 are cleared when the speed sensor sends a wheel speed signal or when Test Mode ends. DTCs C1271 and C1272 are output only in Test Mode.

DTC No.	Detection Item	INF Code	DTC Detection Condition	Trouble Area	Note
C1271	Low Output Signal of Front Speed Sensor RH	-	Detected only during Test Mode.	Front speed sensor RH Sensor installation Front speed sensor rotor RH (Front axle hub sub-assembly RH)	-
C1272	Low Output Signal of Front Speed Sensor LH	-	Detected only during Test Mode.	Front speed sensor LH Sensor installation Front speed sensor rotor LH (Front axle hub sub-assembly LH)	-
C1464	Front Speed Sensor RH Circuit	501 502 503 504 506 507 508	INF Code: 501 At a vehicle speed of 10 km/h (6 mph) or more, speed sensor output from one or two wheels is lower than that from other wheels for 15 seconds or more. INF Code: 502 A malfunction occurs in 2 or more wheels. INF Code: 503 An open is detected in the speed sensor signal circuit for 0.05 seconds or more. INF Code: 504 Instantaneous interruption of sensor signal from the malfunctioning wheel occurs 255 times or more. INF Code: 506 When VM1 voltage is 8.6 V or more, sensor supply voltage drops for 0.5 seconds or more. INF Code: 507 At a vehicle speed of 10 km/h (6 mph) or more, speed sensor output from one wheel is 0 km/h (0 mph) for 1 second or more. INF Code: 508 When VM1 voltage is 8.6 V or more, sensor supply voltage drops for 60 seconds or more.	INF Code: 501, 502, 504, 507 Open or short in speed sensor Improperly installed speed sensor, or abnormal clearance between sensor and rotor Open or short in wire harness Improperly connected connector, deformation or corrosion of terminals Front speed sensor RH Skid control ECU (Brake booster with master cylinder assembly) INF Code: 503 Open or short in speed sensor Open or short in wire harness Improperly connected connector, deformation or corrosion of terminals Front speed sensor RH Skid control ECU (Brake booster with master cylinder assembly) INF Code: 506, 508 Open or short in wire harness Skid control ECU (Brake booster with master cylinder assembly)	-
C1465	Front Speed Sensor LH Circuit	511 512 513 514 516 517 518	INF Code: 511 At a vehicle speed of 10 km/h (6 mph) or more, speed sensor output from one or two wheels is lower than that from other wheels for 15 seconds or more. INF Code: 512 A malfunction occurs in 2 or more wheels. INF Code: 513 An open is detected in the speed sensor signal circuit for 0.05 seconds or more. INF Code: 514 Instantaneous interruption of sensor signal from the malfunctioning wheel occurs 255 times or more. INF Code: 516 When VM1 voltage is 8.6 V or more, sensor supply voltage drops for 0.5 seconds or more. INF Code: 517 At a vehicle speed of 10 km/h (6 mph) or more, speed sensor output from one wheel is 0 km/h (0 mph) for 1 second or more. INF Code: 518 When VM1 voltage is 8.6 V or more, sensor supply voltage drops for 60 seconds or more.	INF Code: 511, 512, 514, 517 Open or short in speed sensor Improperly installed speed sensor, or abnormal clearance between sensor and rotor Open or short in wire harness Improperly connected connector, deformation or corrosion of terminals Front speed sensor LH Skid control ECU (Brake booster with master cylinder assembly) INF Code: 513 Open or short in speed sensor Open or short in wire harness Improperly connected connector, deformation or corrosion of terminals Front speed sensor LH Skid control ECU (Brake booster with master cylinder assembly) INF Code: 516, 518 Open or short in wire harness Skid control ECU (Brake booster with master cylinder assembly)	-

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

When replacing the skid control ECU (brake booster with master cylinder assembly), perform initialization and calibration of the linear solenoid valve.

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PROCEDURE

1.	CHECK HARNESS AND CONNECTOR (MOMENTARY INTERRUPTION)

(a) Using the Techstream, check for any momentary interruptions in the wire harness and connector corresponding to a DTC.

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Chassis > ABS/VSC/TRAC > Data List

Tester Display	Measurement Item	Range	Normal Condition	Diagnostic Note
FR Speed Open	Front speed sensor RH open detection	Error or Normal	Normal: Normal	Error: Momentary interruption
FL Speed Open	Front speed sensor LH open detection	Error or Normal	Normal: Normal	Error: Momentary interruption

Chassis > ABS/VSC/TRAC > Data List

Tester Display
FR Speed Open
FL Speed Open

OK:

Normal (There are no momentary interruptions.)

HINT:

Perform the above inspection before removing the sensor and connector.

NG

GO TO STEP 5

OK

2.	READ VALUE USING TECHSTREAM (FRONT SPEED SENSOR)

(a) Select the Data List on the Techstream.

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Chassis > ABS/VSC/TRAC > Data List

Tester Display	Measurement Item	Range	Normal Condition	Diagnostic Note
FR Wheel Speed	Front speed sensor RH	Min.: 0 km/h (0 mph), Max.: 326 km/h (202 mph)	Vehicle stopped: 0 km/h (0 mph)	When driving at constant speed: No large fluctuations
FL Wheel Speed	Front speed sensor LH	Min.: 0 km/h (0 mph), Max.: 326 km/h (202 mph)	Vehicle stopped: 0 km/h (0 mph)	When driving at constant speed: No large fluctuations

Chassis > ABS/VSC/TRAC > Data List

Tester Display
FR Wheel Speed
FL Wheel Speed

(b) 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 inflation, 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.

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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.	PERFORM TEST MODE INSPECTION (SIGNAL CHECK)

(a) Turn the power switch off.

(b) Perform the sensor check in Test Mode Procedure.

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Chassis > ABS/VSC/TRAC > Utility

Tester Display
Signal Check

OK:

All Test Mode DTCs are cleared.

NG

GO TO STEP 5

OK

4.	RECONFIRM DTC

(a) Turn the power switch off.

(b) Clear the DTCs.

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Chassis > ABS/VSC/TRAC > Clear DTCs

(c) Turn the power switch on (READY).

(d) Perform a road test.

(e) Check if the same DTC is output.

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Chassis > ABS/VSC/TRAC > Trouble Codes

Result	Proceed to
DTCs C1464 and C1465 are not output.	A
DTCs C1464 and/or C1465 are output.	B

HINT:

If troubleshooting has been carried out according to Problem Symptoms Table, refer back to the table and proceed to the next step.

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A

USE SIMULATION METHOD TO CHECK

B

GO TO STEP 10

5.	CHECK FRONT SPEED SENSOR INSTALLATION

(a) Turn the power switch off.

*a No clearance *b OK *c NG

(b) Check the speed sensor installation.

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OK:

There is no clearance between the sensor and the front steering knuckle.

The installation bolt is tightened properly.

NG

INSTALL FRONT SPEED SENSOR CORRECTLY

OK

6.	CHECK FRONT SPEED SENSOR TIP

(a) Remove the front speed sensor.

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(b) Check the front speed sensor tip.

OK:

The sensor tip is free of scratches, oil, and foreign matter.

OK (w/ AVS)

GO TO STEP 14

NG

CLEAN OR REPLACE FRONT SPEED SENSOR

OK (w/o AVS)

7.	CHECK HARNESS AND CONNECTOR (BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY - FRONT SPEED SENSOR)

(a) Install the front speed sensor.

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

(c) Disconnect the A57 skid control ECU (brake booster with master cylinder assembly) connector.

(d) Disconnect the A12 or A13 front speed sensor connector.

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

Standard Resistance:

for RH

Tester Connection	Condition	Specified Condition
A57-18 (FR+) - A12-6 (FR+)	Always	Below 1 Ω
A57-18 (FR+) or A12-6 (FR+) - Body ground	Always	10 kΩ or higher
A57-5 (FR-) - A12-5 (FR-)	Always	Below 1 Ω
A57-5 (FR-) or A12-5 (FR-) - Body ground	Always	10 kΩ or higher

for LH

Tester Connection	Condition	Specified Condition
A57-31 (FL+) - A13-6 (FL+)	Always	Below 1 Ω
A57-31 (FL+) or A13-6 (FL+) - Body ground	Always	10 kΩ or higher
A57-32 (FL-) - A13-5 (FL-)	Always	Below 1 Ω
A57-32 (FL-) or A13-5 (FL-) - Body ground	Always	10 kΩ or higher

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

8.	INSPECT BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY (SENSOR OUTPUT)

(a) Reconnect the A57 skid control ECU (brake booster with master cylinder assembly) connector.

*A for RH *B for LH *a Front view of wire harness connector (to Front Speed Sensor)

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

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

Standard Voltage:

for RH

Tester Connection	Switch Condition	Specified Condition
A12-6 (FR+) - Body ground	Power switch on (IG)	5.7 to 14 V

for LH

Tester Connection	Switch Condition	Specified Condition
A13-6 (FL+) - Body ground	Power switch on (IG)	5.7 to 14 V

NG

REPLACE BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY

OK

9.	RECONFIRM DTC

(a) Turn the power switch off.

(b) w/o AVS

Reconnect the A12 or A13 front speed sensor connector.

(c) w/ AVS

Reconnect the A or B front skid control sensor wire connector.

(d) Clear the DTCs.

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Chassis > ABS/VSC/TRAC > Clear DTCs

(e) Turn the power switch on (READY).

(f) Perform a road test.

(g) Check if the same DTC is output.

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Chassis > ABS/VSC/TRAC > Trouble Codes

Result	Proceed to
DTCs C1464 and/or C1465 are output.	A
DTCs C1464 and C1465 are not output.	B

HINT:

If troubleshooting has been carried out according to Problem Symptoms Table, refer back to the table and proceed to the next step.

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B

USE SIMULATION METHOD TO CHECK

A

10.	REPLACE FRONT SPEED SENSOR

(a) Turn the power switch off.

(b) Replace the front speed sensor.

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NOTICE:

Check the speed sensor signal after replacement.

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NEXT

11.	RECONFIRM DTC

(a) Clear the DTCs.

Click here

Chassis > ABS/VSC/TRAC > Clear DTCs

(b) Turn the power switch on (READY).

(c) Perform a road test.

(d) Check if the same DTC is output.

Click here

Chassis > ABS/VSC/TRAC > Trouble Codes

Result	Proceed to
DTCs C1464 and/or C1465 are output.	A
DTCs C1464 and C1465 are not output.	B

HINT:

If troubleshooting has been carried out according to Problem Symptoms Table, refer back to the table and proceed to the next step.

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B

END

A

12.	REPLACE FRONT AXLE HUB SUB-ASSEMBLY

(a) Turn the power switch off.

(b) Replace the front speed sensor rotor (front axle hub sub-assembly).

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HINT:

The front speed sensor rotor is incorporated into the front axle hub sub-assembly.

If the front speed sensor rotor needs to be replaced, replace the front axle hub sub-assembly.

NOTICE:

Check the speed sensor signal after replacement.

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NEXT

13.	RECONFIRM DTC

(a) Clear the DTCs.

Click here

Chassis > ABS/VSC/TRAC > Clear DTCs

(b) Turn the power switch on (READY).

(c) Perform a road test.

(d) Check if the same DTC is output.

Click here

Chassis > ABS/VSC/TRAC > Trouble Codes

Result	Proceed to
DTCs C1464 and/or C1465 are output.	A
DTCs C1464 and C1465 are not output.	B

HINT:

If troubleshooting has been carried out according to Problem Symptoms Table, refer back to the table and proceed to the next step.

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A

REPLACE BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY

B

END

14.	INSPECT FRONT SKID CONTROL SENSOR WIRE

(a) Install the front speed sensor.

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

(c) Disconnect the A75 or A76 front skid control sensor wire connector.

(d) Disconnect the A or B front skid control sensor wire connector.

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

*A	for RH	*B	for LH
*1	Front Skid Control Sensor Wire	-	-
*a	Front view of wire harness connector (to Front Speed Sensor Side Connector)	*b	Front view of wire harness connector (to Vehicle Side Connector)

Standard Resistance:

for RH

Tester Connection	Condition	Specified Condition
A-1 - A75-6 (FR+)	Always	Below 1 Ω
A-1 or A75-6 (FR+) - Body ground and other terminals	Always	10 kΩ or higher
A-2 - A75-5 (FR-)	Always	Below 1 Ω
A-2 or A75-5 (FR-) - Body ground and other terminals	Always	10 kΩ or higher

for LH

Tester Connection	Condition	Specified Condition
B-1 - A76-6 (FL+)	Always	Below 1 Ω
B-1 or A76-6 (FL+) - Body ground and other terminals	Always	10 kΩ or higher
B-2 - A76-5 (FL-)	Always	Below 1 Ω
B-2 or A76-5 (FL-) - Body ground and other terminals	Always	10 kΩ or higher

NG

REPLACE FRONT SKID CONTROL SENSOR WIRE

OK

15.	CHECK HARNESS AND CONNECTOR (BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY - FRONT SPEED SENSOR)

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

(b) Reconnect the A75 or A76 front skid control sensor wire connector.

(c) Disconnect the A57 skid control ECU (brake booster with master cylinder assembly) connector.

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

Standard Resistance:

for RH

Tester Connection	Condition	Specified Condition
A57-18 (FR+) - A-1	Always	Below 1 Ω
A57-18 (FR+) or A-1 - Body ground	Always	10 kΩ or higher
A57-5 (FR-) - A-2	Always	Below 1 Ω
A57-5 (FR-) or A-2 - Body ground	Always	10 kΩ or higher

for LH

Tester Connection	Condition	Specified Condition
A57-31 (FL+) - B-1	Always	Below 1 Ω
A57-31 (FL+) or B-1 - Body ground	Always	10 kΩ or higher
A57-32 (FL-) - B-2	Always	Below 1 Ω
A57-32 (FL-) or B-2 - Body ground	Always	10 kΩ or higher

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

16.	INSPECT BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY (SENSOR OUTPUT)

(a) Reconnect the A57 skid control ECU (brake booster with master cylinder assembly) connector.

*A for RH *B for LH *a Front view of wire harness connector (to Front Speed Sensor)

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

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

Standard Voltage:

for RH

Tester Connection	Switch Condition	Specified Condition
A-1 - Body ground	Power switch on (IG)	5.7 to 14 V

for LH

Tester Connection	Switch Condition	Specified Condition
B-1- Body ground	Power switch on (IG)	5.7 to 14 V

OK

GO TO STEP 9

NG

REPLACE BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY

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