Lexus ES: Steering Angle Sensor Initialization Incomplete (C1439,C1445)
DESCRIPTION
The skid control ECU (brake booster with master cylinder assembly) acquires the steering angle sensor zero point every time the power switch on (READY) and the vehicle is driven at 35 km/h (22 mph) or more for approximately 5 seconds. The skid control ECU (brake booster with master cylinder assembly) also stores the previous zero point.
If front wheel alignment or the steering wheel position is adjusted without disconnecting the cable from the negative (-) auxiliary battery terminal, or if the yaw rate and acceleration sensor zero point is not acquired after the adjustments have been completed, the skid control ECU (brake booster with master cylinder assembly) detects the difference between the previous zero point and newly acquired zero point and stores this DTC to indicate a poor adjustment.
Warning operation for the steering angle sensor zero point malfunction will be canceled by turning the power switch off.
| DTC No. | Detection Item | INF Code | DTC Detection Condition | Trouble Area | MIL | Note |
|---|---|---|---|---|---|---|
| C1439 | Steering Angle Sensor Initialization Incomplete | 752 | The steering angle sensor zero point is lost (due to instability of supplied power, etc.) and cannot be acquired by the skid control ECU (brake booster with master cylinder assembly). |
| Does not come on | VSC DTC |
| C1445 | Vehicle Driven with Steering Angle Sensor not Initialized | 753 | 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 15 km/h (9 mph) or more for 60 seconds or more without the brake pedal being depressed. |
| Does not come on | VSC DTC |
PROCEDURE
| 1. | CHECK DTC |
(a) Clear the DTCs.
Click here .gif)
(b) Turn the power switch off.
(c) Turn the power switch on (IG) again and check that no CAN communication system DTC is output.
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(d) Turn the power switch on (READY).
(e) 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.
Click here
HINT:
- When CAN communication system DTCs are output, repair the CAN communication system before repairing each corresponding sensor.
- If there is a malfunction in the speed sensor or the yaw rate and acceleration sensor (airbag ECU assembly), an abnormal value may be output although the steering angle sensor is normal.
- If the speed sensor and the yaw rate and acceleration sensor (airbag ECU assembly) DTCs are output simultaneously, repair these malfunctions 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 point calibration, such as when the power source voltage drops.
| Result | Proceed to |
|---|---|
| DTCs C1439 and/or C1445 are output. | A |
| CAN communication system DTCs are output. | B |
| Speed sensor, yaw rate and acceleration sensor and/or steering angle sensor DTCs are output. | C |
| DTCs C1439 and C1445 are not output. | D |
| B |  | INSPECT CAN COMMUNICATION SYSTEM |
| C | | REPAIR CIRCUITS INDICATED BY OUTPUT DTCS |
| D | | USE SIMULATION METHOD TO CHECK |
|
| 2. | CHECK 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.
OK:
The steering wheel is centered correctly.
HINT:
If the front wheel alignment and steering position are adjusted as a result of an off-center steering wheel, acquire the yaw rate and acceleration sensor zero point again after the adjustments are completed.
| NG | | ADJUST FRONT WHEEL ALIGNMENT OR STEERING POSITION |
|
| 3. | RECONFIRM DTC |
(a) Clear the DTCs.
Click here
(b) Turn the power switch off.
(c) Turn the power switch on (READY).
(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 output.
Click here
| Result | Proceed to |
|---|---|
| DTCs C1439 and C1445 are not output. | A |
| Yaw rate and acceleration sensor and/or steering angle sensor DTCs are output. | B |
HINT:
If DTCs C1439 and/or C1445 are 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 source voltage drops.
| A | | END |
| B | | REPAIR CIRCUITS INDICATED BY OUTPUT DTCS |
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