The HECU supplies
battery power to all soleonid valves with a valve relay which is
controlled by the Electronic Control UNIT(ECU).
The valve relay and all
solenoid valves are installed inside the HECU ( Hydraulic and Electronic
Control Unit ).
ABS ECU monitors voltage
of the valve relay to check if ABS ECU can perform ABS control
normally.
When the valve relay is
switched to ON, the HECU will set this code if the solenoid drive voltage
is below permissible voltage ranges for a period of time.
When the valve relay is
switched to OFF, the HECU sets this code if the solenoid drive voltage is
over the permissible voltage range for a period of time.
Item
|
Detecting
Condition
|
Possible cause
|
DTC
Strategy
|
|
| •
|
Open or short of power supply circuit
(ABS2) |
|
Case1
(Open)
|
Enable
Conditions
|
| •
|
If the valve relay is switched on and
the reference voltage of valve relay < 5±0.5V continuously
for 56ms, the failure is
detected. | |
Case2
(Short
or
leakage)
|
Enable
Conditions
|
| •
|
If the valve relay is switched off and
voltage of valve relay > 6±0.5V or < 2.5±0.5V
continuously for 56ms, the failure is
detected. | |
Fail Safe
|
| •
|
The ABS/EBD/ESC functions are
inhibited. |
| •
|
The ABS/EBD/ESC warning lamps are
activated. | |
| 1. |
Connect scantool to Data Link
Connector(DLC). |
| 2. |
Ignition "ON" & Engine
"OFF". |
| 3. |
Select the "Actuation Test" mode on the
scantool. |
| 4. |
Inspect operating status of all valves with
Actuation Test.
Specification
: It's normal if operating sound is
heard.
|
|
| 5. |
Do all valves operate normally?
|
|
▶ Fault is
intermittent caused by poor connection in power harness (ABS2)
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
"Power Circuit Inspection"
procedure.
|
|
Open or Short Check
| 1. |
Ignition "ON" & Engine
"OFF". |
| 2. |
Measure voltage between power(ABS2) terminal
of the HECU harness connector and chassis ground.
|
| 3. |
Is the measured value within
specifications?
|
|
▶ Go to
"Ground Circuit Inspection" procedure.
|
|
|
▶ Check for
open or blown 40A (ABS2) fuse referring to "Circuit
Diagram".
▶ Repair open or short in
power circuit between battery and HECU harness connector and
then, go to "Verification Of Vehicle Repair"
procedure.
|
|
| Ground Circuit
Inspection |
Open or Short Check
| 1. |
Ignition "OFF" & Engine
"OFF". |
| 2. |
Disconnect the HECU
connector. |
| 3. |
Measure resistance between ground terminal of
the HECU harness connector and chassis ground.
Specification
: Approx. below 1Ω
| |
| 4. |
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 ground circuit between HECU harness connector
and chassis ground, 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.
|
|
