The one pressure sensor ,installed in the master cyclinder, sense the brake oil pressure to judge driver’s brake intention when ESP is operating. There are movable and unmovable ceramic disk in pressure sensor. when the pressure is applied to the disk, the distance between the disks changes. Therefore the distance between the disks changes linearly when the pressure is applied to the movable disk by break opreation . Max. measurable pressure is 170bar. The sensor output is a analog signal in proportion to supply voltage, and the HECU recognizes a pressure value according to signal ratio about supply voltage.
Each unfiltered input signal voltage is monitored to be in the range of 0.2V±0.1V< input signal voltage < 4.8V±0.1V. A failure is detected if the output signal value is out of specified range for more than 1s or pressure sensor self test form is against to specification during self test.
Item
Detecting Condition
Possible Cause
DTC Strategy
? Voltage Monitoring
? Open or short of pressure sensor circuit
? Faulty pressure sensor
? Faulty HECU
Case1
Detect Mode
? Initial Check
? Outside the ABS control cycle
? Inside the ABS control cycle
? Diagnosis mode
? Failure mode
Enable Conditions
? Vmcp > 4.8±0.1V or Vmcp < 0.2±0.1V continus 1sec.
- The monitoring starts 1sec after power up.
Case2
? When sensor self test form is against to sensor specification.
Case3
? While the vehicle is stopped affter driving over 40kph for 3 times, If predefined value of pressure signal is not detected, ECU detect the failure after sensor self test.
Fail Safe
? Inhibit the TCS/ESP control and allow the ABS/EBD control.
Meanwhile, stop checking the TCS/ESP switch failure under the TCS/ESP control.
? The TCS/ESP warning lamps are activated.