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 if an
abnormal speed change ratio is detected while the vehicle speed is more
than 2Km/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.
Item
|
Detecting
Condition
|
Possible cause
|
DTC
Strategy
|
|
| •
|
Improper installation of
wheel speed
sensor |
| •
|
Abnormal Rotor and wheel
bearing |
| •
|
Faulty Wheel speed
sensor | |
Enable
Conditions
|
Case1
|
| •
|
Max. wheel velocity exceeds 20km/h and
the wheel velocity is 40% of max. wheel velocity. if this
condition is lasted for 2
minutes. |
| •
|
Max. wheel velocity exceeds 40km/h and
the wheel velocity is 60% of max. wheel velocity. if this
condition is lasted for 2
minutes. | |
Case2
|
| •
|
Controller counts the number of the
wheel acceleration of 100g[(25km/h) for 7ms]. When the numbers
at one wheel exceed 56 times, or When the numbers at more two
wheels exceed
5 times, controller recognize the
failure. |
| •
|
Controller counts the number of the
wheel acceleration of 70g[(17.5km/h) for 7ms]. When the
numbers at one wheel exceed 126 times, or When the numbers at
more two wheels exceed 20 times, controller recognize the
failure. |
| •
|
Controller counts the number of the
wheel deceleration of
-100g[(-25km/h) for 7ms]. When the
numbers at each wheel exceed 56 times, controller recognize
the failure. |
| •
|
The wheel deceleration of
-100g[(-25km/h) for 7ms] causes the controller to start
monitoring this failure and to compare the wheel velocity with
the vehicle velocity from next cycle. When its difference of
-100g is continued for more than 140msec,
controller recognize the
failure. |
| •
|
In case that any sensor failure at other
wheel was already detected, When the numbers of 100g at each
wheel exceed 5
times, or When the numbers of 70g at
each wheel exceed 20 times, controller recognize the
failure.
- The counter of speed jump is cleared
every 30min.
- This monitoring is performed for the
period that the velocity of each wheel exceeds
2km/h. | |
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 40km/h.
(24mph) |
| 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 conn
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
"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?
|
|
▶ Fault is
intermittent caused by faulty HECU, wheel speed sensor or
external noise, an interference between
harnesses.
Thoroughly check
connectors for looseness, poor connection, bending, corrosion,
contamination, deterioration, or damage.
Repair as necessary 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 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 40kmh.
(24mph)) |
| 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.
|
|
