4.
Inspect opearating status of TCS(USV) / ESP(HSV) 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 wheel cylinder.
The HECU monitors the operation of the valves by checking the drive circuit of the solenid valves, and then sets this code when the unexpected 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 | ● Faulty HECU | |
Case 1 | Monitoring Period | ● Once after ignition on at standstill if the BLS is off ● At vehicle speed ≥ 15 km/h if the BLS is on. | |
Enable Conditions | ● The test actuates all valves in series to detect shorts or shunts between the valve lines. Faults are detected if there is an error during the test. | ||
Case 2 | Monitoring Period | ● The drift test executes only once during an ignition Cycle. The test is triggered if the following conditions are fulfilled : 10 min 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 defective 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 TCS(USV) / ESP(HSV) valve with Actuation Test.
Specification : It's normal if operating sound is heard.
Does a TCS(USV) / ESP(HSV) valve operate normally?
▶ Fault is intermittent caused by poor connection in power harness (ABS2) and/or HECU's connector or wasrepaired 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.
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.
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. (Start and drive vehicle in gear and maintain vehicle speed at or above 15km/h. (9mph)
Are any DTCs present?
▶ Go to the applicable troubleshooting procedure.
▶ System performing to specification at this time.
