Allante V8-273 4.5L (1991)
Body Control Module: Initial Inspection and Diagnostic Overview
Low Oil Pressure
Oil Pressure Circuit
TEST CONDITION:
Engine speed greater than 300 rpm.
FAILURE CONDITION:
1.
Oil pressure less than 3 psi for 12 seconds.
ACTION TAKEN:
1.
Display "Low Oil Pressure" message on the CCDIC.
2.
Turn on Oil Pressure lamp on IPC.
The BCM monitors the 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 gauge 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 DIC and command the IPC to turn on the Oil Pressure
Lamp.
Condition Possible Causes:
^
Erroneous Message - short to ground on circuit 31 or shorted switch or sensor.
^
No Message - open in circuits 31 or 736.
