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.
The ABS ECU monitors the pump motor continuously. (Self check by actuating the pump motor at 15km/h isn’t performed).
Item
Detecting Condition
Possible Cause
DTC Strategy
Voltage monitoring
Open or short of power supply circuit (ABS1)
Faulty HECU
Case1
Monitoring
Period
Once per loop when pump motor is deactivated, but not check during detected high, low voltage or when the controller is switched off.
Enable
Conditions
A failure is detected if pump motor voltage > 0.93V continued for 1.8sec.
Case2
Once per loop when pump motor is activated.
A failure is detected if pump motor voltage < 7.3V continued for 1.8sec.
Case3
A failure is detected if the short circuit event has continuously occurred 3 times.
- The short circuit event is counted if pump switch voltage > 0.5V continued for about 1ms when the pump motor is activated
In case no electrical pump motor short circuit has been detected, a failure is detected if the mechanically locked pump event has continuously occurred 10 times.
- A mechanically locked pump event is counted if pump switch voltage > 0.5V continued for about 20ms when the pump motor is activated.
Case4
The active test is initiated by the controller once per IGN cycle in following conditions.
1. The vehicle speed exceeds 8 kph and the ABS warning lamp indicates that there was a failure detected during the previous IGN cycle.
2. The vehicle speed exceeds 20 kph and the brake is not applied.
3. The vehicle speed exceeds 40 kph.
The test is always done after the end of a pump activation by ABS/TCS/ESP functions.
A defect of the pump is assumed if an insufficient alternator voltage is detected within 14 or 21 ms after the deactivation. The pump motor will then be activated again for about 1.8 s (2nd pump test) and the alternator voltage is evaluated again after deactivation. A failure is detected if this second evaluation also does not show sufficient alternator voltage.
Fail-Safe
When ABS is inactive
Inhibit pump motor activation, deactivate all control functions but EBD.
During active ABS control
Inhibit pump motor activation, deactivate all control functions but EBD on completion of ABS cycle.
The ABS/ ESP warning lamps are activated.