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 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 corresconding valve.
Item | Detecting Condition | Possible cause | |
DTC Strategy |
•
Voltage Monitoring | 1. Faulty HECU | |
Case 1 | MonitoringPeriod |
•
Once when Vveh is over 30kph(18.6mph) after ignition on | |
Enable Conditions |
•
When the fault from valve is detected by monitoring valve feedback signal at the test. (The test acutuate valve in series and monitors short fault of valve lines.) - Stop ABS/EBD/ESP control immediately when a fault occurs | ||
Case 2 | MonitoringPeriod |
•
In case of BLS ON, once when Vveh is over 15kph after ignition on
•
In case of BLS OFF, once when Vveh is over 6kph after ignition on | |
Enable Conditions |
•
Monioring if the electrical feedback signal mismatch the unactuation signal to the corresponding valve for more than 40ms or actuation signal over 60ms. Monitoring system reports a failure if the situation is the same after 60ms from the timing. - Stop ABS/EBD/ESP control immediately when a fault occurs | ||
Fail Safe |
•
The ABS/EBD/ESP functions are inhibited.
•
The ABS/EBD/ESP warning lamps are activated. | ||
