The HECU supplies battery power to all solonid valves with a valve relay which is controlled by the Electronic Control UNIT(ECU). The valve relay and all solenoid valves are installed inside the HECU (Hydraulic and Electronic Control Unit ).
The HECU monitors voltage of the valve relay to check if the HECU can perform ABS control normally.
When the valve relay is switched to ON, the HECU will set this code if the solenoid drive voltage is below permissible voltage ranges for a period of time.
When the valve relay is switched to OFF, the HECU sets this code if the solenoid drive voltage is over the permissible voltage range for a period of time.
Item
Detecting Condition
Possible Cause
DTC Strategy
Voltage monitoring
Open or short in power supply circuit (IGN+)
Case1
Monitoring
Period
Once during startup.
Enable
Conditions
Watchdog and valve relay function is tested during startup.
A failure is detected if the valve relay/Enable remains in off position when it is turned on and vice versa. Reason could be short to GND or UZ, interrupted lines or a defective output stage etc.
Case2
Continuous
A Fault is detected if valve relay voltage < 0.8 * battery voltage for a time 500ms.
Case3
If valve relay malfunction and supply solenoid valve short to battery or supply solenoid valve and medium or high ohmic short of valve relay (or a valve) to valve relay voltage, solenoid valve voltage or GND are detected.
Fail-Safe
No valve actuation possible.
The ABS/EBD/ESP functions are inhibited.
The ABS/EBD/ESP warning lamps are activated.