"Low Oil Pressure" Message and Oil Pressure Telltale

TEST CONDITION(S)
1) Engine RPM greater than 300

FAILURE CONDITION(S)
1)Oil pressure less than 3 PSI for 12 seconds

ACTION TAKEN
1) Display "Low Oil Pressure message on Computer Control Driver Information Center (CCDIC).
2) Turn on Oil Pressure telltale on Instrument Panel Cluster (IPC).

DESCRIPTION
The BCM monitors oil pressure input on pin 3D10. The oil pressure input circuit is made up of two sensors in parallel, an oil pressure sensor and an oil pressure switch. This input is used for the oil pressure gage display, oil pressure telltale and "Low Oil Pressure" message. 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 open at normal oil pressure and closes if oil pressure drops below 3 psi. Under normal engine running conditions, the oil pressure switch will be open and the oil pressure sensor will have a variable resistance. The BCM will see a varying voltage on pin 3D10.

If the oil pressure drops too low, the voltage on pin 3D10 will drop either because the oil pressure sensor resistance is low or the oil pressure switch has closed. If this condition exists for 12 seconds, the BCM will send the "Low Oil Pressure" message to the Driver Information Center (DIC) and command the IPC to turn on the Oil Pressure telltale.

DIAGNOSIS
Condition Possible Causes
Erroneous Message Short to ground in circuit 31 or shorted switch or sensor
No Message Open in circuits 31 or 736