Lexus NX: Steering Angle Sensor Initialization Incomplete (C1439,C1445)
DESCRIPTION
The skid control ECU (brake booster with master cylinder assembly) acquires the steering sensor zero point every time the power switch is turned on (IG) and the vehicle is driven at 35 km/h (22 mph) or more for approximately 5 seconds. The ECU also stores previous zero points.
DTCs C1439 and C1445 will be cleared when the power switch is turned off.
| DTC No. | Detection Item | INF Code | DTC Detection Condition | Trouble Area | Note |
|---|---|---|---|---|---|
| C1439 | Steering Angle Sensor Initialization Incomplete | 752 | After the steering sensor zero point calibration is cleared due to, for example, fluctuations in the power source, the steering sensor zero point calibration cannot be obtained for 0.048 seconds of continuous driving. |
| - |
| C1445 | Vehicle Driven with Steering Angle Sensor not Initialized | 753 | Steering sensor zero point calibration cannot be obtained when the vehicle is driven without a record of steering sensor zero point calibration at a speed of 35 km/h (22 mph) or more for 60 seconds or more. |
| - |
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 sensor zero point calibration, such as when the power source voltage drops when the auxiliary battery is removed. Confirm whether this condition occurred.
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.
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- When a speed sensor or the 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 other 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
| 1. | CHECK DTC |
(a) Clear the DTCs.
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(b) Turn the power switch off.
(c) Turn the power switch on (IG) again and check that no CAN communication system DTCs are 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, yaw rate and acceleration sensor and steering sensor DTCs are output.
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| 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 sensor DTCs are output. | C |
| DTCs C1439 and C1445 are 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 although 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.
- If DTC C1439 and/or C1445 is not output again, the DTC may have been stored due to a temporary loss of the steering sensor zero point calibration, such as when the power source voltage drops.
| B | .gif) | INSPECT CAN COMMUNICATION SYSTEM |
| C | | REPAIR CIRCUITS INDICATED BY OUTPUT DTCS |
| D | | USE SIMULATION METHOD TO CHECK |
|
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| 2. | CHECK STEERING 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 steering wheel is centered correctly while driving straight ahead.
HINT:
If the front wheel alignment and steering position are adjusted as a result of an off-center steering wheel, acquire yaw rate and acceleration sensor zero point again after the adjustments are completed.
OK:
The steering wheel is centered correctly.
| NG | | ADJUST FRONT WHEEL ALIGNMENT OR STEERING POSITION |
|
| 3. | RECONFIRM DTC |
(a) Turn the power switch off.
(b) Clear the DTCs.
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(c) Turn the power switch off.
(d) Turn the power switch on (READY).
(e) Drive the vehicle at a speed of 35 km/h (22 mph) or more and turn the steering wheel to the right and left.
(f) Check if the same DTC is output.
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| Result | Proceed to |
|---|---|
| DTCs C1439 and C1445 are not output. | A |
| Yaw rate and acceleration sensor and/or steering sensor DTCs are 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 sensor zero point calibration, such as when the power source voltage drops.
| A | | END |
| B | | REPAIR CIRCUITS INDICATED BY OUTPUT DTCS |
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