The HECU is composed of a ECU (Electronic Control Unit ) and a HCU( Hydraulic Control Unit) , so the HECU hardware includes all solenoid valves inside the unit as well as the ECU.
This trouble code is set when the solenoid valves or operating circuit are malfunctioning as well as the trouble of HECU.The HECU moitors the operation of the valves by checking the drive circuit of the solenoid valves,and then sets this code when the unexpcted drain voltage is detected, and also sets this code when the HECU module itself is out of order. For example, when the EEPROM data red by master processor is different from the data sent before, or when the master/slave processor detects abnormal operation in RAM, Status Register, Interrupt ,Timer, A/D converter, cycle time,the HECU sets this code.
Item | Detecting Condition | Possible cause | |
DTC Strategy | ● Internal monitoring | ● Faulty HECU | |
Detect Mode | ● Initial Check ● Outside the ABS control cycle ● Inside the ABS control cycle ● Diagnosis mode ● Failure mode | ||
Enable Conditions | Case1(Solenoid Valve) | ● When the valve relay is switched off, the drain voltage of the solenoid drive MOSFET is over the criterion, which is continued for 56msec. ● When the valve relay is switched on and a solenoid off, the drain voltage of the solenoid drive MOSFET is under the criterion, which is continued for 56msec. ● When the valve relay and a solenoid are switched on, the drain voltage of the solenoid drive MOSFET is over the criterion, which is continued for 56msec. | |
Case2(ECU - EEPROM, MCU) | ● When the MCU can’t erase or write a data of the EEPROM. ● When the master/slave processor detects abnormal operation in RAM, status register, interrupt, timer, A/D converter and cycle time. | ||
Fail Safe | ● System down. Both the ABS and the EBD function are inhibited. - The valve relay and all solenoids are prevented from being switched on. ● The ABS and the EBD warning lamps are activated. | ||
