The HECU supplies
operating voltage with Steering angle senor (12V), Yaw & later G
sensor (12V), G sensor (5V).
The HECU monitors supply
voltage of each sensor for normal ESC control.
If supply voltage is out
of specified range ESC warning lamps are turned on and ESC controls are
inhibited.
A failure is detected if
the external sensor supply voltage is out of the specified range for more
than the specified min. fault duration.
Item
|
Detecting
condition
|
Possible cause
|
DTC
Strategy
|
| •
|
Battery Voltage
Monitoring | |
| •
|
Poor connection in power supply circuit
to sensor | |
Enable
Conditions
|
| •
|
During sensor power ON, If the voltage
of sensor power is out of the specified range for
500ms. |
| •
|
During sensor power OFF, If the voltage
of sensor power is out of the specified range for
500ms. | |
Fail
Safe
|
| •
|
Inhibit the ESC control and allow the
ABS/EBD control. |
| •
|
The ESC warning lamps are
activated. | |
| 1. |
Connect scantool to Data Link
Connector(DLC). |
| 2. |
Ignition "ON" & Engine
"ON". |
| 3. |
Monitor the "BATTERY VOLTAGE, 5 VOLT
REFERENCE" parameter on the scantool.
Specification
:
BATTERY VOLTAGE (Approx. 10V ~
16V)
5 VOLT REFERENCE (Approx.
5V)
|
|
| 4. |
Is parameter displayed within
specifications?
|
|
▶ Fault is
intermittent caused by poor connection in 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
"Power Circuit Inspection"
procedure.
|
|
Open or Short Check
| 1. |
Ignition "ON" & Engine
"OFF". |
| 2. |
Measure voltage between power terminal of the
steering angle sensor, Yaw rate & lateral G sensor, G sensor
harness connector and chassis ground.
Specification
: Approx. 12V (steering angle sensor,
Yaw rate& lateral G sensor), Approx. 5V (G
sensor)
| |
| 3. |
Is the measured value 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 power circuit between HECU harness connector
and steering angle sensor, Yaw rate & lateral G sensor, G
sensor harness connector and then go to "Verification of
vehicle Repair" procedure.
▶ If
there is no problem in power 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.
|
|
| 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.
|
|
