The ABS ECU supplies battery power to all solonid valves by way of 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 ).
ABS ECU monitors voltage of the valve relay to check if ABS ECU can perform ABS control normally. The valve relay voltage monitor function tests the supply voltage valve relay voltage of the valves via the Valve feedback lines. If three or more valve response faults occur simultaneously, a fault "supply voltage of valves" is registered.
Item
Detecting Condition
Possible cause
Case1
DTC Strategy
? Valve supply voltage monitoring
? Open or short of power supply circuit
? Faulty HECU
Monitoring Period
? Continuous
Enable Conditions
? The monitor function tests the supply voltage of the valves via the Valve feedback lines. If valve relay voltage< 80% of battery is continued for 500msec it is interpreted as a fault.
Fail Safe
? No valve actuation possible. ABS is switched off immediately.
? The ABS and the EBD warning lamps are activated.
Case2
? Valve relay stick monitoring
? Detected during initialization
? The valve relay cannot be switched off.Valve supply voltage remains High although Valve relay is Low. (valve relay frozen)
? It is not possible to switch off the valve relay after a fault occurred. ABS is switched off after the valve and pump motor test.
? The ABS warning lamp is activated and the EBD warning lamp is not activated.