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 |
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Voltage Monitoring |
•
External noise.
•
Faulty pressure sensor |
Enable Conditions |
•
If input signal is noisy, Which the gradient of the sensor signal is larger than predefined value for specific times, ECU detect the failure.
•
Outside an ABS/ESP control, And after normal operation of BLS, If the pressure sensor signal is higher than 20bar and BLS is low for 3sec, ECU detect the failure. | |
Fail Safe |
•
Inhibit the ESP control and allow the ABS/EBD control.
•
The ESP warning lamp is activated. |
