The pressure sensor, installed in the HECU, sense the brake oil pressure to judge driver's brake intention when ESP is operating.
If pressure of master cyclinder is applied to pressure sensor, the strain of the piezo element is changed and then the resistance of brige circuit is chanded according to changed strain.
Therefore this changed resistance changes output voltage of brige circuit and output voltage changes linearly.
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.
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 | ● 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. |
Connect scantool to Data Link Connector(DLC).
Ignition "ON" & Engine "ON".
Press the brake pedal.
Monitor the "PRESSURE SENSOR" parameter on the Scantool.
Specification : Approx. 60bar ~150bar (There is difference in displayed parameter according to braking force)
Fig 1) Test Condition : Ignition "ON" & Engine "ON".
Normal Data
Fig 2) Test Condition : Ignition "ON" & Engine "ON" & Brake "ON".
Normal data (There is difference in displayed parameter according to braking force)
Whenever brake pedal is pushed down, is the pressure sensor's scantool data changed?
 | ▶ Fault is caused by having been repaired and HECU memory was not cleared. Clear the DTC and then go to "Verification of Vehicle Repair" procedure. |
 | ▶ Go to "Component Inspection" procedure. |
Ignition "OFF".
Ignition "ON" & Engine "OFF".
Connect scantool and select "Diagnostic Trouble Codes(DTCs)" mode.
Using a scantool, Clear DTC.
Select "Diagnostic Trouble Codes(DTCs)" mode again.
Are any DTCs present ?
| ▶ Substitute with a known-good HECU and check for proper operation. If problem is corrected, replace HECU and then go to "Verification of Vehicle Repair" procedure. |
| ▶ Fault is intermittent caused by faulty HECU. Go to "Verification of Vehicle Repair" procedure. |
After a repair, it is essential to verify that the fault has been corrected.
Connect scantool and select "Diagnostic Trouble Codes(DTCs)" mode
Using a scantool, Clear DTC.
Operate the vehicle within DTC Detecting Condition in General Information.
Using a scantool, Check DTC present.
Are any DTCs present ?
| ▶ Go to the applicable troubleshooting procedure. |
| ▶ System performing to specification at this time. |
