Pinpoint Test AQ: The Low Oil Pressure Message Center Warning Indicator Is Never/Always On: Hybrid

WARNING: This page is about a different car, the 2011 Mercury Milan, 2011 Lincoln MKZ, and 2011 Ford Fusion. However, it is still accessible from the selected car via links, so may be relevant.

Due to the need to turn the internal combustion engine on and off during operation with the key in the RUN position, the low oil pressure message center warning indicator requires two inputs. The first input is engine rpm and the second input is oil pressure switch state. When the IPC detects engine oil pressure and receives an rpm state over 500 rpm from the internal combustion engine, the IPC turns off the low oil pressure warning indicator. If the oil pressure switch indicates low oil pressure and the rpm is less than 500 rpm, the low oil pressure message center warning indicator remains off.

With the oil pressure switch closed, the IPC senses the low reference voltage and turns off the low oil pressure warning indicator, provided engine rpm is greater than 500 rpm. When the engine oil pressure is low, the engine oil pressure switch opens, sending the reference voltage high. The IPC senses the reference voltage has moved high and turns the low oil pressure warning indicator on.

The IPC receives the engine rpm status from the PCM over the High Speed Controller Area Network (HS-CAN) communication bus.

If the engine rpm status is missing or invalid for less than 5 seconds, the IPC controls the low oil pressure message center warning based upon current oil pressure switch state and using the last known good rpm message received. If the engine rpm status is invalid for more than 5 seconds, the IPC assumes that the rpm is greater than 500 rpm and defaults full control of the low oil pressure message center warning indicator to the actual oil pressure switch state. If the engine rpm status is missing for more than 5 seconds, the IPC sets DTC U0100:00 in continuous memory and assumes that the rpm is greater than 500 rpm, defaulting full control of the low oil pressure message center warning indicator to the actual oil pressure switch state.

This pinpoint test is intended to diagnose the following:

Wiring, terminals or connectors
Engine oil pressure switch
Base engine oil pressure concern
IPC