B131 Engine Oil Pressure Circuit Problem

Code B131 - Engine Oil Pressure Circuit Problem:

Wiring Diagram for Code B131 - Engine Oil Pressure Circuit Problem:

CODE B131 - ENGINE OIL PRESSURE CIRCUIT PROBLEM

Circuit Description:

Important!


The oil pressure gage uses a variable resistor to control the signal voltage to the BCM. The BCM supplies a voltage on CKT 313 to the sensor. When the engine is not running (low oil pressure) the sensor's resistance is low and the signal voltage is pulled Lo through sensor ground, CKT 736. When the engine is running (increased on pressure) the sensors resistance becomes greater and the signal voltage increases, therefore the BCM will see a Hi signal voltage (open CKT). This signal voltage will vary between 5V (open CKT) and OV (shorted CKT).

Code B131 will set during "display-on-entry", if the signal voltage is high (open CKT). In other words, when the engine is not running, oil pressure is low and the switch contacts should close and pull the signal voltage low. A shorted to ground circuit will show up as low off pressure all the time.



Test Description:

1. BCM input B126 displays off pressure at HI or LO, depending on the voltage state at the BCM.

2. Checks to see if the HI reading is due to the circuit or the switch. With the engine off, if the display changes from HI to LO, when the connector is jumpered to ground, the BCM and wiring are OK.

3. Checks to see if the HI reading is due to the BCM or the circuit If the display changes from HI to LO, when BCM terminal cavity is backprobed to ground, the BCM is OK.



Note on Intermittents:

If an intermittent code B131 is being set, manipulate CKT 313. When BCM input B126 change-of-state indicator displays an "x", the failure has been induced.