10194108-10194105-10194117-10194119-10194110-10194114-10194112-10194115

COMPONENT LOCATION

General Description

The Steering angle sensor(SAS) is joined to the multi function switch and uses a CAN communication. The SAS is used to determine turning direction and speed of the steering wheel. The HECU uses the signals from the SAS when performing ESP-related calculations.

DTC Description

If the SAS signal is different from calculated value by yaw-rate sensor and wheel speed sensor, mechanically impossible SAS signal is detected, there is a difference between SAS signal and driving condition of the vehicle calculated from yaw-rate sensor and lateral G sensor, a failure is detected.

DTC Detecting Condition

Item

Detecting Condition

Possible cause

DTC Strategy

●

Signal Monitoring

●

Open or short of steering angle sensor circuit

●

Inoperative steering angle sensor

●

Inoperative HECU

Case 1

Monitoring Period

●

Continuous

Enable Conditions

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During normal driving conditions the long time filtered driving direction is straight ahead. The long time filtered SAS-value is equivalent to the offset. If the offset value exceeds a threshold of approximately 15 deg a SAS-fault is determined. Failure detection time depends on the driving distance, vehicle speed and on the amount of failed SAS signal. Within 30 km of symmetrical driving the calculated offset corresponds to the sensor offset.

Case 2

Monitoring Period

●

Continous (If the following conditions are satisfied)

After SAS-initialization and vehicle reference speed ＞ 1.4 m/s (5 km/h)

No under voltage

At least one SAS-message was sent in the current 20 ms-cycle.

Enable Conditions

●

A SAS-gradient-failure is set, if

Signal gradient (steering angle velocity) from one 20 ms-cycle to another is higher than 40° or

Change of this gradient (steering angle acceleration) is higher than 15° : | (LwInK0K1 . LwInK1K2)| ＞ 15° and | (LwInK0K1 + LwInK1K2)| ＞ 15°

- LwInK0K1 : Difference of the SAS-signal between the current 20 ms-cycle and the last 20 ms-cycle.

- LwInK1K2 : Difference of the SAS-signal between the last 20 ms-cycle and 20 ms-cycle before.

Case 3

Monitoring Period

●

Continuous (After initialization and no under voltage detected)

Enable Conditions

●

If value is higher than 665° + 90° tolerance for more than 300 ms a fault is determined.

Case 4

Monitoring Period

●

Continuous (during driving)

Enable Conditions

●

Based on a vehicle model a reference SAS signal is build. The difference between measured SAS signal and SAS signal calculated from yaw-rate sensor signal is evaluated for fault detection.

Dependent on the driving conditions failures in size of [10 + 60 m/s / vehicle reference speed] deg at steering angle are recognized within 400 ~ 4800 ms through three possible recognition paths:

Curve Branch (lateral G ＞ 2 m/s² and left and right curve driving)

Stability Branch (no large wheel speed differences and stable acceleration)

Straight ahead Branch (lateral G ＜ 0.5 m/s² and yaw rate ＜ 2 deg/s).

The recognition time depends on the active branch (the time is shorter in a relation 1):2):3)-4:2:1) and the value of the permissible time threshold dependent on the deviation between the compared signals (small deviation → long detection time, large deviation → small detection time).

Case 5

Monitoring Period

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Initialization once in every ignition cycle.

●

The monitoring is active until a reset by a change in the SAS signal or until a right and left cornering can be recognized.

Enable Conditions

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If there is no change in the signal, but a right and left cornering has been recognized, a fault is determined. (lateral G ＞ 2 m/s² in combination with a yaw rate ＞ 6 °/s in both directions).

- At a minimum change of e.g. 5° in the signal, the monitoring is reset.

Case 6

Monitoring Period

●

Continuous (during driving)

Enable Conditions

●

The measured yaw rate and the yaw rates, calculated from the wheel speed sensor and SAS are compared. If the signals don’t fit and forwards driving is detected, a fault is determined.

Case 7

Monitoring Period

●

Continuous (during driving)

Enable Conditions

●

Under normal conditions, two SAS messages are sent in one 20 ms cycle, which is shown by an increase of the message counter by 2. If the message counter shows an increase higher than 3 or lower than 1 in one 20 ms-cyle, a fault is stored after 160 ms.

Fail Safe

●

Reduced controller function caused by inoperative SAS signal. ABS/EBD control is available.

●

The ESP warning lamp is activated.

Monitor Scantool Data

Connect scantool to Data Link Connector(DLC).

Ignition "ON" ＆ Engine "ON".

Turn the steering wheel to the left or right.

Monitor the "Steering Sensor" parameters on the Scantool.

Whenever steering wheel is turned, is the steering sensor's scantool data changed?

(1)

Connect scantool to Data Link Connector (DLC).

(2)

Ignition "ON" ＆ Engine "ON".

(3)

Turn the steering wheel to the full left or right position.

(4)

Monitor the "steering sensor" parameters on the Scantool.

(5)

Is parameter displayed within specifications?

▶ Go to "W/Harness Inspection" procedure.

▶ Go to number 6. procedure.

▶ Go to "W/Harness Inspection" procedure.

Perform steering angle sensor calibration.

(1)

Ignition "ON" ＆ Engine "OFF".

(2)

Line up the steering wheel in a straight.

(3)

Connect scantool to Data Link Connector(DLC).

(4)

Go in Anti-Rock brake system. (figure 4).

(5)

Perform steering angle sensor calibration. (figure 5).

(6)

Go to "Compnent Inspection" Precedure.

Whenever steering wheel is turned, is the steering sensor's scantool data changed HIGH/LOW?

▶ Fault is intermittent caused by poor connection in steering sensor harness and/or HECU's connector or was repaired and HECU memory was not cleared. Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage. Repair or replace as necessary and then go to "Verification of Vehicle Repair" procedure.

▶ Go to "W/Harness Inspection" procedure.

Terminal and Connector Inspection

Many malfunctions in the electrical system are caused by poor harness(es) and terminals. Faults can also be caused by interference from other electrical systems, and mechanical or chemical damage.

Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage.

Has a problem been found?

▶ Repair as necessary and then go to "Verification Of Vehicle Repair" procedure.

▶ Go to "Component Inspection" procedure.

Component Inspection

Ignition "OFF".

Ignition "ON".

Connect scantool and select "Diagnostic Trouble Codes (DTCs)" mode.

Using a scantool, Clear DTC.

Operate the vehicle within DTC Detecting Condition in General Information. (turn right and left at least 1 time)

Select "Diagnostic Trouble Codes (DTCs)" mode again.

Are any DTCs present ?

(1)

Substitute with a known-good steering angle sensor and check for proper operation. If problem is corrected, replace sensor and then go to "Verification of Vehicle Repair" procedure.

(2)

Substitute with a known-good HECU and check for proper operation. If problem is corrected, replace HECU and then go to "Verification of Vehicle Repair" procedure.

▶ Fault is intermittent caused by faulty HECU or was repaired and HECU memory was not cleared. go to "Verification of Vehicle Repair" procedure.

Verification of Vehicle Repair

After a repair, it is essential to verify that the fault has been corrected.

Connect scantool and select "Diagnostic Trouble Codes (DTCs)" mode

Using a scantool, Clear DTC.

Operate the vehicle within DTC Detecting Condition in General Information

Are any DTCs present?

▶ Go to the applicable troubleshooting procedure.

▶ System performing to specification at this time.