Toyota Tacoma (2015-2018) Service Manual: Steering Angle Sensor Initialization Incomplete (C1439,C1445)

Toyota Tacoma (2015-2018) Service Manual / Brake Control / Dynamic Control Systems / Vehicle Stability Control System(for Vacuum Brake Booster) / Steering Angle Sensor Initialization Incomplete (C1439,C1445)

DESCRIPTION

The skid control ECU (brake actuator assembly) acquires steering angle sensor zero point every time the ignition switch is turned ON and the vehicle is driven at 35 km/h (22 mph) or more for approximately 5 seconds. The ECU also stores the previous zero point.

The steering angle sensor zero point malfunction warning is canceled by turning the ignition switch off.

DTC No.	Detection Item	DTC Detection Condition	Trouble Area
C1439	Steering Angle Sensor Initialization Incomplete	After the steering angle sensor zero point calibration is cleared due to, for example, fluctuations in the power source, the steering angle zero point calibration cannot be obtained for 0.048 seconds of continuous driving.	Steering angle sensor (Spiral cable with sensor sub-assembly) Yaw rate and acceleration sensor (Airbag sensor assembly)
C1445	Vehicle Driven with Steering Angle Sensor not Initialized	Steering angle sensor zero point calibration cannot be obtained when the vehicle is driven without a record of steering angle sensor zero point calibration at a speed of 35 km/h (22 mph) or more for 30 seconds or more without the brake pedal being depressed.	Steering angle sensor (Spiral cable with sensor sub-assembly) Yaw rate and acceleration sensor (Airbag sensor assembly)

CAUTION / NOTICE / HINT

NOTICE:

Before proceeding with the inspection, explain to the customer that the output DTC is related to temporary loss of the steering angle zero point calibration, such as when the power voltage drops when the battery is removed, and confirm that this condition occurred.

HINT:

When DTC U0073, U0124 or U0126 is output together with DTC C1439 and/or C1445, inspect and repair the trouble areas indicated by DTC U0073, U0124 or U0126 first (See page ).
When the speed sensor or the yaw rate and acceleration sensor (airbag sensor assembly) has trouble, DTCs for the steering angle sensor (spiral cable with sensor sub-assembly) may be stored even when the steering angle sensor (spiral cable with sensor sub-assembly) is normal. When DTCs for the speed sensor or yaw rate and acceleration sensor (airbag sensor assembly) are output together with other DTCs for the steering angle sensor (spiral cable with sensor sub-assembly), inspect and repair the speed sensor and yaw rate and acceleration sensor (airbag sensor assembly) first, and then inspect and repair the steering angle sensor (spiral cable with sensor sub-assembly).

PROCEDURE

CHECK DTC

(a) Clear the DTCs (See page (b) Turn the ignition switch off. ).

(b) Turn the ignition switch off.

(c) Turn the ignition switch to ON again and check that no CAN communication system DTC is output (See page (d) Drive the vehicle at a speed of 35 km/h (22 mph) or more and turn the steering ).

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

HINT:

If there is a malfunction in the speed sensor or the yaw rate and acceleration sensor (airbag sensor assembly), an abnormal value may be output although the steering angle sensor (spiral cable with sensor sub-assembly) is normal.
If the speed sensor and the yaw rate and acceleration sensor (airbag sensor assembly) DTCs are output simultaneously, repair the sensors and inspect the steering angle sensor (spiral cable with sensor sub-assembly).
If DTC C1439 or C1445 is not output again, the DTC may have been stored due to a temporary loss of the steering angle zero point calibration, such as when the power voltage drops.

Result

Result		Proceed to
DTC is output	C1439 and/or C1445	A
	Relating to CAN communication system	B
	Relating to speed sensor or yaw rate and acceleration sensor (airbag sensor assembly)	C
DTC is not output		D

GO TO CAN COMMUNICATION SYSTEM (HOW TO PROCEED WITH TROUBLESHOOTING)

REPAIR CIRCUITS INDICATED BY OUTPUT DTCS

USE SIMULATION METHOD TO CHECK

2.	PERFORM STEERING ANGLE SENSOR ZERO POINT CALIBRATION

(a) Drive the vehicle straight ahead at 35 km/h (22 mph) or more for at least 5 seconds.

(b) Check that the centered position of the steering wheel is correctly set while driving straight ahead.

HINT:

If the front wheel alignment and steering position are adjusted as a result of an abnormal centered position of the steering wheel, acquire the yaw rate and acceleration sensor zero point again after the adjustments are completed.

OK:

The centered position of the steering wheel is correctly set.

ADJUST FRONT WHEEL ALIGNMENT OR STEERING POSITION

3.	RECONFIRM DTC

(a) Turn the ignition switch off.

(b) Clear the DTCs (See page (c) Start the engine. ).

(d) Drive the vehicle at a speed of 35 km/h (22 mph) or more and turn the steering wheel to the right and left.

(e) Check if the same DTC is recorded (See page HINT: HINT: ).

HINT:

If DTC C1439 or C1445 is not output again, the DTC may have been stored due to a temporary loss of the steering angle zero point calibration, such as when the power voltage drops.

Result

Result	Proceed to
DTCs C1439 and C1445 are not output	A
Yaw rate and acceleration sensor and/or steering angle sensor DTC is output	B

END

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