C1237 Primary Pressure Sensor-Signal - Automotive Repair Guides & Equipment

COMPONENT LOCATION

GENERAL DESCRIPTION

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.

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.

In spite of no brake switch signal, master cylinder pressure exceeds 20bar when brake switch is normal.

DTC DETECTING CONDITION

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.

DIAGNOSTIC CIRCUIT DIAGRAM

COMPONENT INSPECTION

1.	Ignition “OFF”.

2.	Ignition “ON” & Engine “OFF”.

3.	Connect scantool and select “Diagnostic Trouble Codes(DTCs)” mode.

4.	Using a scantool, Clear DTC.

5.	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
	▶ This fault may be intermittently caused.

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