Brake System

Component Location





General Description

The one pressure sensor ,installed in the master cylinder, sense the brake oil pressure to judge driver's brake intention when ESC is operating. If pressure of master cylinder is applied to pressure sensor, the strain of the piezo element is changed and then the resistance of bridge circuit is changed according to changed strain. Therefore this changed resistance changes output voltage of bridge 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.

DTC Description

The failure is detected if the pressure sensor signal noise is out of normal range, or the pressure sensor signal is changed abnormally, or In spite of no brake switch signal, master cyclinder pressure exceeds 20 bar when brake switch is normal.

DTC Detecting Condition





Terminal and Connector Inspection

1. Many malfunctions in the electrical system are caused by poor harness(es) and terminal conditions. Faults can also be caused by interference from other electrical systems, and mechanical or chemical damage.
2. Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage.
3. Has a problem been found?
YES
> Repair as necessary and then go to "Verification Of Vehicle Repair" procedure.
NO
> Go to "Signal Circuit Inspection" procedure.

Signal Circuit Inspection

1. Ignition "ON" & Engine "OFF".
2. Press the brake pedal.
3. Measure voltage between terminal "1" of the pressure sensor harness connector and chassis ground by using the oscilloscope.

Specification : 0.2 ± 0.1 V ~ 4.8 ± 0.1 V





4. Is the measured voltage within specifications?
YES
> Go to "Component Inspection" procedure.
NO
> Check for damaged harness and poor connection in pressure sensor harness between terminal "1" of the pressure sensor harness connector and terminal "12" of the HECU harness connector. Repair as necessary and then go to "Verification Of Vehicle Repair" procedure.
> If OK, substitute with a known-good pressure sensor and check for proper operation. If problem is corrected, replace pressure sensor and then go to "Verification Of Vehicle Repair" procedure.

Component Inspection

1. Ignition "OFF".
2. Engine "ON".
3. Does warning lamp remain On?
YES
> 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.
NO
> Fault is intermittent caused by open or short of pressure sensor harness, faulty pressure sensor and/or faulty HECU or was repaired and HECU memory was not cleared. Go to the applicable troubleshooting procedure.

Verification Of Vehicle Repair

After a repair, it is essential to verify that the fault has been corrected.
1. Connect scantool and select "Diagnostic Trouble Codes (DTCs)" mode.
2. Using a scantool, Clear DTC.
3. Operate the vehicle within DTC Detecting Condition in General Information.
4. Are any DTCs present ?
YES
> Go to the applicable troubleshooting procedure.
NO
> System performing to specification at this time.