The Steering wheel angle
sensor uses two sensors ( A-sensor and B-sensor ) to determine the
direction of the rotation.
The main components of
each sensor are LED, photo transistor and slit plate.
The slit plate, which
has 45 holes, is installed between LED and photo transistor, and generates
signals if slit plate rotates according to the steering wheel
rotation.
The sensor signals are
generated by photo transistor which is driven whenever the light passes
through the holes. The HECU detects operating speed and direction of the
steering wheel by this input signal, and the signal is used to input
signal for anti-roll control.
This monitoring function
monitors the changing point of N-signal with measured steering angle from
ST1 and ST2.
If N-signal changing
point differs more than predefined degree, the failure is
detected.
If there is no variation
of the steering wheel angle for predefined time ECU detect the
failure.
Item
|
Detecting
Condition
|
Possible cause
|
DTC
Strategy
|
|
| •
|
Faulty steering wheel
sensor | |
Enable
Conditions
|
| •
|
The STN is low more than ±20 degrees for
70msec. |
| •
|
When the steering wheel is turned more
than 370±5 degrees, if center is not detected, ECU detects the
failure. |
| •
|
When the steering wheel angle is higher
than 700 degrees ECU detects the
failure. |
| •
|
During straight driving, if the steering
wheel angle is larger than 55±5 degree ECU detects the
failure. |
| •
|
When the curve is detected after driving
straight, if there is no variation of the steering wheel angle
for 3sec, ECU detect the
failure. |
| •
|
While the vehicle drive 60±5 degree ↔
-60±5 degree, if STN is not detected low, ECU detect the
failure. |
| •
|
While steering angle sensor wheel
through center, if steering angle sensor is against
specification three times, ECU detect the
failure. | |
Fail
Safe
|
| •
|
Inhibit the ESC control and allow the
ABS/EBD control. |
| •
|
The ESC warning lamp is
activated. | |
| 1. |
Connect scantool to Data Link
Connector(DLC). |
| 2. |
Ignition "ON" & Engine
"ON". |
| 3. |
Turn the steering wheel to the left or
right. |
| 4. |
Monitor the "STEERING ANGLE SENSOR" parameters
on the Scantool.
Specification
: If the parameters are changed
according to wheel position during steering the wheel, it is
normal condition.
|
|
| 5. |
Whenever steering wheel is turned, is the
steering sensor's scantool data changed?
|
|
▶ 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
"Terminal and Connector Inspection"
procedure.
|
|
| Terminal and Connector
Inspection |
| 1. |
Many malfunctions in the electrical system are
caused by poor harness(es) and terminal condition. Faults can also
be caused by interference from other electrical systems, and
mechanical or chemical damage. |
| 2. |
Thoroughly check connectors for looseness,
poor connection, bending, corrosion, contamination, deterioration,
or damage. |
| 3. |
Has a problem been found?
|
|
▶ Repair as
necessary and then go to "Verification Of Vehicle Repair"
procedure.
|
|
|
▶ Go to
"Signal Circuit Inspection"
procedure.
|
|
| Signal Circuit
Inspection |
Open or Short Check
| 1. |
Ignition "ON" & Engine
"ON". |
| 2. |
Turn the steering wheel to the left or
right. |
| 3. |
Measure waveform between signal terminal of
the HECU harness connector and chassis ground with
osciloscope.
Specification
: Check the voltage range (HIGH :
2.9±0.1V ~ 4.4±0.1V LOW : 1.2±0.1V ~2.1±0.1V) of the sensor
signal in case of turning left, turning right, center
position.
If normal waveforms such as fig1, 2, 3
are detected in each condition, It is
normal.
|
Normal Waveform
|
| 4. |
Is the measured waveform within
specifications?
|
|
▶
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.
|
|
|
▶ Repair
open or short in signal circuit between steering angle sensor
harness connector and HECU harness connector, and then go to
"Verification Of Vehicle Repair" procedure.
▶ If there is no problem in signal circuit,
Substitute with a known-good HECU and check for
properoperation.
|
|
Steering Angel Sensor Check
| 1. |
Ignition "ON" & Engine
"ON". |
| 2. |
Turn the steering wheel to the left or
right. |
| 3. |
Measure waveform between signal terminal of
the steering angle sensor harness connector and chassis ground with
osciloscope.
Specification
: Check the voltage range (HIGH :
2.9±0.1V ~ 4.4±0.1V LOW : 1.2±0.1V ~2.1±0.1V) of the sensor
signal in case of turning left, turning right, center
position.
If normal waveforms such as fig1, 2, 3
are detected in each condition, It is
normal.
|
Normal Waveform
|
| 4. |
Is the measured waveform within
specifications?
|
|
▶ Fault is
intermittent caused by poor connection in steering sensor
harness and/or HECU's connector.
Go
to "Verification Of Vehicle Repair"
procedure.
|
|
|
▶ If STN
signal is HIGH on center position, Check for improper
installation of steering angle sensor
Repair as necessary and then go to "Verification Of
Vehicle Repair" procedure.
▶ If
sensor mounting state is normal, Substitute with a known-good
steering angle sensor and check for proper
operation.
If problem is corrected,
replace steering angle sensor and then 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.
| 1. |
Connect scantool and select "Diagnostic
Trouble Codes(DTCs)" mode. |
| 2. |
Using a scantool, Clear
DTC. |
| 3. |
Operate the vehicle within DTC Detecting
Condition in General Information. |
| 4. |
Using a scantool, Check DTC
present. |
| 5. |
Are any DTCs present ?
▶ Go to the applicable troubleshooting
procedure.
▶ System performing to specification at this
time. |
