The wheel speed sensor
is the essential component the ABS ECU uses to calculate vehicle speed and
to determine whether wheel lock occurs.
For example, rear wheel
speed signal is used as a referecnce value, for vehicle speed, in front
wheel drive vehicles, and if a difference between front and rear wheel
speed occurs, then ABS control is performed.
Wheel speed sensor is
active hall-sensor type.
The ABS ECU monitors the
wheel speed sensor signal continuously.
This code is set when
the sensor air gap is out of specified range or when the ABS control cycle
is continued abnormally.
The HECU checks for air
gap malfunctioning by monitoring the sensor signal at speeds between 2Km/h
to 10 Km/h.
Warning lamp is turned
OFF unless additional faults are detected when the IG KEY is turned ON
again, and wheel speed is more than 10 Km/h (6.2mph).
Item
|
Detecting
Condition
|
Possible cause
|
DTC
Strategy
|
|
| •
|
Improper installation of wheel speed
sensor |
| •
|
Abnormal Rotor and wheel
bearing |
| •
|
Faulty Wheel speed
sensor | |
Case1
(Large
Air-Gap)
|
Enable
Conditions
|
| •
|
When the minimum wheel velocity is 2km/h
and the velocity of other wheels exceed 10km/h (6.2mph) with
the acceleration of < 0.4g, the controller start comparing
the velocity of other wheels except the min. wheel. if their
difference below 4km/h (2.5mph) is continued for 140msec,
Otherwise, if their difference beyond 4km/h (2.5mph) or
>0.4g is continued for 2
minutes. |
| •
|
In < 0.4g, when the velocity of more
two wheels is 2km/h
(1.2mph) and the max. wheel velocity
exceeds 10km/h
(6.2mph), the condition is continued for
20 sec. Otherwise,
In >0.4g, the condition is 2
minutes. |
| •
|
After velocity of 4 wheel exceeds 10km/h
(6.2mph), when velocity of 1 wheel or 2 wheel is 2km/h
(1.2mph)and difference of other 2 wheel velocity is less than
4km/h (2.5mph) under that those velocity is more than 10km/h
(6.2mph), if that conditions are continued for 12
seconds.
- This monitoring is performed for the
period that the minimum velocity rises from 2km/h (1.2mph) to
10km/h (6.2mph). | |
Case2
(long
term
ABS mode)
|
Enable
Conditions
|
| •
|
During the ABS control cycle, if the
wheel velocity of 2km/h
(1.2mph) is lasted for more than
12sec. |
| •
|
If the ABS control cycle is continued
for more than 36sec. | |
Fail Safe
|
| 1. |
Inhibit the ABS/ESC control, allow the
EBD control. The ABS/ESC warning lamps are activated, the EBD
warning lamp is
not
activated. |
| 2. |
The ABS/EBD/ESC functions are inhibited.
The ABS/EBD/
ESC warning lamps are
activated. | |
Sensor Type
|
Output Voltage
|
Tooth Count
|
Airgap
|
HIGH
|
LOW
|
Active
Type
|
1.4V
|
0.7V
|
52
|
0.4~1.5mm
|
| 1. |
Ignition "ON" & Engine
"ON". |
| 2. |
Connect scantool to Data Link
Connector(DLC). |
| 3. |
Start and drive vehicle in gear and maintain
vehicle speed at or above 10km/h.
(6.2mph) |
| 4. |
Monitor the "WHEEL SPEED" parameter on the
Scantool.
Specification
: Compare with other parameters
related to wheel speed sensor.
If it is the same as other parameters,
it is in normal condition.
|
|
| 5. |
Is parameter displayed within
specifications?
|
|
▶ Fault is
intermittent caused by poor connection in wheel speed 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 O Vehicle Repair"
procedure.
|
|
|
▶ Go to
"Component Inspection"
Procedure.
|
|
Wheel Speed Sensor Circuit Check
| 2. |
Ignition "ON" & Engine
"OFF". |
| 3. |
Turn the wheel by
hand. |
| 4. |
Measure waveform between signal terminal of
the wheel speed sensor harness connector and chassis ground with
osciloscope.
Specification
:
High : 1.18~1.68V
Low : 0.59~0.84V
|
Normal Waveform
|
| 5. |
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.
|
|
|
▶ Check for
improper installation of wheel speed sensor. If NG, repair as
necessary and then go to "Verification Of Vehicle Repair"
procedure.
▶ Check for damage of
rotor teeth or wheel bearing. If NG, repair as necessary and
then go to "Verification Of Vehicle Repair"
procedure.
▶ Substitute with a
known-good Wheel speed sensor and check for proper
operation.
If problem is corrected,
replace Wheel speed 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. (Start and drive vehicle in gear
and maintain vehicle speed at or above 10kmh.
(6.2mph)) |
| 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.
|
|
