The ABS ECU(Electronic Control Unit) checks the battery voltage to determine, as a safety issue, whether the ABS system can operate normally or not. The normal battery voltage range is essential for controlling the ABS system as instended.
The ABS ECU monitors the battery voltage by reading the value of voltage. When the voltage is lower than the expected normal value, this code is set. The ABS/TCS/ESP functions are prohibited and the EBD function is allowed on LOW VOLTAGE CONDITION, the ABS/EBD/TCS/ESP functions are prohibited on UNDER VOLTAGE CONDITION. If the voltage recovers, to within normal operating ranges, then the controller returns to normal operations as well.
Item | Detecting Condition | Possible cause |
DTC Strategy | ● Battery Voltage Monitoring | ● Poor connection in power supply circuit (IGN+) ● Faulty HECU |
Detect Mode | ● Initial Check ● Outside the ABS control cycle ● Inside the ABS control cycle ● Diagnosis mode ● Failure mode | |
Case1 (Low voltage) | Enable Conditions | ● When Vign<9.5V±0.5V is continued for 500msec during Vref >= 7Km/h. ● When Vign<8.5V±0.5V is continued for 500msec during Vref < 7Km/h or ABS/BTCS/ESP control. - If IGN voltage is recovered to normal operating voltage, the system recovers to normal state. |
Fail Safe | ● Outside the ABS control cycle : inhibit the ABS/TCS/ESP control of front wheels and allow the ABS/TCS/ESP control of rear wheels, deactivating the motor and the ABS/TCS/ESP warning lamps are directly switched on. When the voltage recovers the normal operating range, enable ABS/TCS/ESP functions and warning lamps are switched off and erase the error code. ● Inside the ABS control cycle : inhibit the ABS/TCS/ESP control of front wheels and allow the ABS/TCS/ESP control of rear wheels, deactivating the motor. The ABS/TCS/ESP warning lamps are directly switched on and the state keeps continuously. The error code is always stored. | |
Case2 (Under voltage) | Enable Conditions | ● When Vign<7.2V±0.5V is continued for 28msec. - If IGN voltage is recovered to normal operating voltage, the system recovers to normal state. |
Fail Safe | ● System down. The ABS/EBD/TCS/ESP functions are inhibited. - The valve relay and all solenoids are prevented from being switched on. ● The ABS/EBD/TCS/ESP warning lamps are activated. |
