Toyota 4Runner: Steering Angle Sensor Initialization Incomplete (C1439,C1445)

Toyota 4Runner Service Manual / Brake / Brake Control / Dynamic Control Systems / Vehicle Stability Control System(for Hydraulic Brake Booster) / Steering Angle Sensor Initialization Incomplete (C1439,C1445)

DESCRIPTION

The skid control ECU acquires steering angle sensor zero point every time the ignition switch is turned to ON and the vehicle is driven at 40 km/h (25 mph) or more for approximately 10 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 Code	DTC Detection Condition	Trouble Area
C1439	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 60 seconds of continuous driving.	Steering angle sensor (Spiral cable sub-assembly) Yaw rate and acceleration sensor Master cylinder solenoid (Skid control ECU)
C1445	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 36 km/h (22 mph) or more for 30 seconds or more without the brake pedal being depressed.

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 calibration, such as when the power voltage drops when the battery is removed, and confirm that this condition occurred.
When replacing the master cylinder solenoid, perform calibration (See page ).

HINT:

When DTC U0073, U0123, U0124 and/or U0126 is output together with DTC C1439 and/or C1445, inspect and repair the trouble areas indicated by DTC U0073, U0123, U0124 and/or U0126 first (See page ).

When the speed sensor or the yaw rate and acceleration sensor has trouble, DTCs for the steering angle sensor may be stored even when the steering angle sensor is normal. When DTCs for the speed sensor or yaw rate and acceleration sensor are output together with other DTCs for the steering angle sensor, inspect and repair the speed sensor and yaw rate and acceleration sensor first, and then inspect and repair the steering angle sensor.

PROCEDURE

CHECK DTC

(a) Clear the DTCs (See page ).

(b) Turn the ignition switch off.

(d) Drive the vehicle at a speed of 40 km/h (25 mph) and turn the steering wheel to the right and left, and then check that no speed sensor and yaw rate and acceleration sensor DTCs are output (See page ).

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	C
DTC is not output		D

HINT:

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

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 40 km/h (25 mph) or more for at least 10 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) Clear the DTCs (See page ).

(b) Turn the ignition switch off.

(d) Drive the vehicle at a speed of 40 km/h (25 mph) or more and turn the steering wheel to the right and left.

(e) Check if the same DTC is output (See page
).

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

HINT:

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

END

REPAIR CIRCUITS INDICATED BY OUTPUT DTCS

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