Lexus NX: Steering Angle Sensor Circuit (C1231)

Lexus NX Service Manual / Brake / Brake Control / Dynamic Control Systems / Electronically Controlled Brake System / Steering Angle Sensor Circuit (C1231)

DESCRIPTION

The skid control ECU (brake booster with master cylinder assembly) receives steering sensor signals via CAN communication. When a malfunction occurs in the communication line with the steering sensor, DTC U0126 (Lost Communication with Steering Angle Sensor Module) is stored.

DTC No.	Detection Item	INF Code	DTC Detection Condition	Trouble Area	Note
C1231	Steering Angle Sensor Circuit	701 702 703	INF Code: 701 While steering sensor communication is enabled, a malfunction signal output is received during the sensor self-check (sensor malfunction). INF Code: 702 While steering sensor communication is enabled, a malfunction signal output is received during the sensor self-check (internal malfunction). INF Code: 703 While steering sensor communication is enabled, a malfunction signal output is received during the sensor self-check (+B malfunction).	Steering sensor internal malfunction	-

DTC No.

Detection Item

INF Code

DTC Detection Condition

Trouble Area

Note

C1231

Steering Angle Sensor Circuit

701

702

703

INF Code: 701
- While steering sensor communication is enabled, a malfunction signal output is received during the sensor self-check (sensor malfunction).
INF Code: 702
- While steering sensor communication is enabled, a malfunction signal output is received during the sensor self-check (internal malfunction).
INF Code: 703
- While steering sensor communication is enabled, a malfunction signal output is received during the sensor self-check (+B malfunction).

Steering sensor internal malfunction

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

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

HINT:

When U0126 is output together with C1231, inspect and repair the trouble areas indicated by U0126 first.
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When a speed sensor or yaw rate and acceleration sensor (airbag ECU assembly) is malfunctioning, DTCs for the steering sensor may be output even when the steering sensor is normal. When DTCs for a speed sensor or the yaw rate and acceleration sensor (airbag ECU assembly) are output together with DTCs for the steering sensor, inspect and repair the speed sensor and yaw rate and acceleration sensor (airbag ECU assembly) first, and then inspect and repair the steering sensor.

PROCEDURE

CHECK DTC

(a) Clear the DTCs.

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Chassis > ABS/VSC/TRAC > Clear DTCs

(b) Turn the power switch off.

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(d) Drive the vehicle at a speed of 35 km/h (22 mph), turn the steering wheel to the right and left, and check that no speed sensor and/or yaw rate and acceleration sensor DTCs are output.

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Chassis > ABS/VSC/TRAC > Trouble Codes

Result	Proceed to
DTC C1231 is output.	A
CAN communication system DTCs are output.	B
Speed sensor and/or yaw rate and acceleration sensor DTCs are output.	C
DTC C1231 is not output.	D

HINT:

When CAN communication system DTCs are output, repair the CAN communication system before repairing each corresponding sensor.
If there is a malfunction in a speed sensor or the yaw rate and acceleration sensor (airbag ECU assembly), an abnormal value may be output even though the steering sensor is normal.
If speed sensor and yaw rate and acceleration sensor DTCs are output simultaneously, repair the sensors and inspect the steering sensor.

INSPECT CAN COMMUNICATION SYSTEM

REPAIR CIRCUITS INDICATED BY OUTPUT DTCS

USE SIMULATION METHOD TO CHECK

2.	CHECK HARNESS AND CONNECTOR (POWER SOURCE TERMINAL)

(a) Turn the power switch off.

*a	Front view of wire harness connector (to Steering Sensor)

(b) Remove the steering wheel and column cover.

(d) Disconnect the I6 steering sensor connector.

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

Standard Voltage:

Tester Connection	Condition	Specified Condition
I6-4 (IG1) - Body ground	Power switch on (IG)	11 to 14 V
I6-5 (BAT) - Body ground	Always	11 to 14 V

REPAIR OR REPLACE HARNESS OR CONNECTOR (POWER SOURCE CIRCUIT)

3.	CHECK HARNESS AND CONNECTOR (GROUND TERMINAL)

(a) Turn the power switch off.

*a	Front view of wire harness connector (to Steering Sensor)

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

NOTICE:

Before measuring the resistance of the steering sensor, turn the power switch off and leave the vehicle for 1 minute or more without operating the key, switches or opening or closing the doors.

Standard Resistance:

Tester Connection	Condition	Specified Condition
I6-1 (ESS) - Body ground	1 minute after power switch off	Below 1 Ω

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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REPLACE STEERING SENSOR

REPAIR OR REPLACE HARNESS OR CONNECTOR (GROUND CIRCUIT)

SEE MORE:

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DESCRIPTION This DTC is stored if the parking assist ECU judges as a result of its self check that a synchronization problem is occurring in the image signal sent from the passenger side television camera assembly to the parking assist ECU. DTC No. Detection Item DTC Detection Condition Tro

Installation

INSTALLATION CAUTION / NOTICE / HINT HINT: A bolt without a torque specification is shown in the standard bolt chart. Click here PROCEDURE 1. INSTALL FRONT BUMPER SIDE RETAINER LH (a) Attach the 2 claws to install the front bumper side retainer LH. (b) Attach the clip. (c) Install t

Lexus NX: Steering Angle Sensor Circuit (C1231)

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Installation