The HECU is composed of a ECU (Electronic Control Unit ) and a HCU( Hydraulic Control Unit) , HCU is composed of a source of hydraulic pressure and modulator valve block. Increase and decrease of hydraulic pressure is opreated by electronic motor, According to a detected signal by wheel speed sensor, The hydraulic pressure which is needed for control is supplied by pump. The HCU’ function which is composed of a accumulator, return pump, solenoid valve is to increase, decrease or maintain the hydralic pressure supplied to a wheel cylinder by operating return pump according to HECU control signal while ABS control.
The HECU monitors the operation of the IC components such as memory, register, A/D converter and so on. The ECU sets this code when the EEPROM data read by the master processor is different than prior data writed, or when the master/slave processor detects abnormal operation in RAM, Status Register, Interrupt, Timer, A/D converter or cycle time.
Item | Detecting Condition | Possible cause | |
DTC Strategy |
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Internal monitoring |
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Faulty HECU | |
Case1 | Monitoring Period |
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Continuous | |
Enable Conditions |
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If Internal control unit failures of the master/slave processor or peripheral integrated circuits is detected. | ||
Case2 | Monitoring Period |
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Directly after ignition on, during reading of EEPROM-values | |
Enable Conditions |
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Failure is set if checksum not correct or PSW-EEPROM-Handler reported unknown failure during EEPROM-value reading.
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If EEPROM reading sequence take longer then 3s, a failure is set. | ||
Fail Safe |
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The ABS/EBD/ESP functions are inhibited.
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The ABS/EBD/ESP warning lamps are activated. | ||
