The ABS ECU supplies battery power to the electric motor by way of a motor relay which is controlled by the Electronic Control Unit(ECU). The electric motor pump supplies hydraulic pressure to all wheel brake calipers by operating the piston inside the pump.
The ABS ECU monitors the pump motor relay or fuse open, open or short in motor or motor lock and then sets this code if a malfunction is detected.
Item
Detecting Condition
Possible cause
DTC Strategy
? Battery Voltage Monitoring
? Open or short of power supply circuit (ABS2)
? Faulty HECU
Case1(Motor Relay Open or Motor Short to BATT)
Detect Mode
? Outside the ABS control cycle
? Inside the ABS control cycle
? Diagnosis mode
Enable Conditions
? When the motor relay is ON and the reference voltage of motor is under the Criterion for 49msec continuously.
Case2(Motor Lock)
? The controller starts monitoring the motor voltage for 84msec from the time when the motor relay is switched off. if the motor voltage is under the criterion for 49msec after shutting off the motor, the motor is reactivated for 500msec. After shutting off the motor 84msec and the above check is performed again for a maximum of two times. When the motor voltage is not normal even on the second check, the controller recognizes it as failure.
Case3(Fuse Open, Motor Open, Motor Short to GND)
? Initial Check
? Failure mode
? The controller starts monitoring the motor after 1.8sec from the time when the motor relay is switched off.
When the motor voltage is over the criterion for 200msec continuously.
Fail Safe
? Only the ABS function is inhibited. The ABS warning lamp is activated and the EBD warning lamp is not activated.
? When the motor relay is switched on during the ABS control, the reference voltage of motor is under the criterion, which is continued for 49msec :Inhibit the ABS control of front wheels and allow the ABS control of rear wheels, deactivating the motor. (in only motor failure). After the controller completes the ABS control, only the ABS function is inhibited. The ABS warning lamp is activated and the EBD warning lamp is not activated.