4.
Inspect opearating status of inlet valve with Actuation Test.
Specification : It's normal if operating sound is heard.
The HECU is composed of an ECU (Electronic Control Unit ) and an HCU( Hydraulic Control Unit), so the HECU hardware includes all solenoid valves inside the unit as well as the ECU. Solenoid valves are switched to ON, OFF by HECU when the ABS is activated. Solenoid valves function is to increase, decrease or maintain the hydralic pressure supplied to a brake caliper.
The HECU monitors the operation of the valves by checking the drive circuit of the solenid valves, and then sets this code when the unexpcted drive voltage is detected. For example, the HECU sets the DTC if the electrical feedback signal does not match the actuation signal for the corresponding valve.
Item | Detecting Condition | Possible cause | |
DTC Strategy | ● Voltage monitoring | ● Inoperative HECU | |
Case 1 | Monitoring Period | ● Continuous | |
Enable Conditions | ● The electrical feedback signal does not match the actuation signal for the corresponding valve for more than 30 ms. - Current controlled valves and under voltage conditions :detection time is 80 ms | ||
Case 2 | Monitoring Period | ● Immediately after power on ● every 20 s - The Test is canceled if any control, valve actuation takes place or if the Vehicle is in motion and the BLS is on. | |
Enable Conditions | ● A Fault is found if UVR is not within 0.1*battery voltage ＜ valve relay voltage ＜ 0.8*battery voltage ● A Fault is found if valve relay voltage ≥ 0.2*battery voltage. - After that all valves are switched on sequential, valve relay voltage and valve feedback is measured. | ||
Case 3 | Monitoring Period | ● The Valve and Pump motor Test is performed once after ignition on if vehicle speed is ＞= 15 km/h. | |
Enable Conditions | ● The valve and pump motor test detects electrical actuation malfunction of ABS valves. The test actuates all valves in series (to detect short cuts or shunts between the valve lines). Faults are detected if there is an error during the test. | ||
Case 4 | Monitoring Period | ● The drift test executes only once during an ignition Cycle. The test is triggered if the following conditions are fulfilled : 10min after power up or end of control
| |
Enable Conditions | ● The drift test is executed only once during an ignition Cycle.If it detects partly shorted valve coils,almost inoperative coils or malfunction of the valve driver, a failure is recognized. | ||
Fail Safe | ● Valve cannot be actuated or valve is incorrectly actuated. This may result in locked wheels or wheels without pressure. ● ABS/EBD/ESP function is prohibited. ● ABS/EBD/ESP warning lamp is turned ON. | ||
Connect scantool to Data Link Connector(DLC)
Ignition "ON" ＆ Engine "OFF".
Select the "Actuation Test" mode on the scantool.
Inspect opearating status of inlet valve with Actuation Test.
Specification : It's normal if operating sound is heard.
Does a inlet valve operate normally?
▶ Fault is intermittent caused by inoperative valve or was repaired and HECU memory was not cleared. Go to the pplicable troubleshooting procedure.
▶ Go to "W/Harness Inspection" procedure.
Many malfunctions in the electrical system are caused by poor harness(es) and terminals. Faults can also be caused by interference from other electrical systems, and mechanical or chemical damage.
Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage.
Has a problem been found?
▶ Repair as necessary and then go to "Verification Of Vehicle Repair" procedure.
▶ 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.
After a repair, it is essential to verify that the fault has been corrected.
Connect scantool and select "Diagnostic Trouble Codes (DTCs)" mode
Using a scantool, Clear DTC.
Operate the vehicle within DTC Detecting Condition in General Information
Are any DTCs present?
▶ Go to the applicable troubleshooting procedure.
▶ System performing to specification at this time.
