Stop Engine Low Oil Pressure & Oil Pressure Telltale & Chime

Low Oil Pressure Circuit:

CIRCUIT DESCRIPTION:
The BCM monitors oil pressure on two inputs, "2B9" and "3D4." Both inputs are provided by the same oil pressure sensor. The oil pressure sensor contacts A and "B" are used only for the oil pressure gage display. The oil pressure switch contacts "C" and "D" and are used for the oil pressure telltale, "STOP ENGINE - LOW OIL PRESSURE" message and the audible chime. The oil pressure sensor is a variable resistor with a high resistance at high oil pressure and low resistance at low oil pressure. The oil pressure switch is closed at normal oil pressure and opens if the oil pressure drops below 3 psi.

Under normal engine running conditions the BCM will receive ignition voltage at pin "3D4" when the oil pressure switch is closed. If the switch opens below 3 psi and remains open for at least 2 seconds when the engine RPM is greater than 300, the BCM will ground pin "3D4," send the "STOP ENGINE - LOW OIL PRESSURE" message to the DIC, turn "ON" the oil pressure telltale and activate the chime.

TEST CONDITION(S):
1. Ignition 3 "ON."
2. Engine RPM greater than 300.

FAILURE CONDITION(S):
1. Oil pressure switch open.

ACTION TAKEN:
1. Display "STOP ENGINE - LOW OIL PRESSURE" message on CCDIC.
2. Turn on "OIL PRESSURE" telltale on IPC.
3. Activate chime.

DIAGNOSIS:

Condition Possible Causes

Erroneous Message Short to ground in CKT 313 or open switch.

No Message Shorted switch or short to voltage in CKT 313.