The pressure sensor, installed in the HECU, senses the brake oil pressure to judge a driver's brake intention when the ESP program is operated. If pressure of master cyclinder is applied to pressure sensor, the strain of the piezo element is changed and then the resistance of bridge circuit is changed according to the changed strain. Therefore this changed resistance changes the output voltage of bridge circuit and the output voltage changes linearly. The sensor output is an analog signal in proportion to the supply voltage, and the HECU recognizes a pressure value according to signal ratio about supply voltage.
The failure is detected if the pressure sensor signal noise is out of normal range, or the pressure sensor signal is changed abnormally.
In spite of no brake switch signal, master cylinder pressure exceeds 20bar when brake switch is normal.
Item
Detecting Condition
Possible cause
DTC Strategy
Voltage Monitoring
Open or short of pressure sensor circuit
Faulty pressure sensor
Faulty HECU
Monitoring Period
Continueosly on driving
Enable Conditions
The pressure sensor-offset value must be in the range of ± 15 bar. A failure is detected if this range is exceeded.
Fail Safe
The ABS/ESP functions are inhibited.
The ABS/ESP warning lamps are activated.