Pinpoint Tests AQ: The Low Oil Pressure Message Center Warning Indicator Is Never/Always On
Instrumentation, Message Center and Warning Chimes
Pinpoint Tests
Pinpoint Test AQ: The Low Oil Pressure Message Center Warning Indicator Is Never/Always On
Refer to Wiring Diagram Set 60 (Fusion/Milan/MKZ, Fusion Hybrid/Milan Hybrid), Instrument Cluster for schematic and connector information. Diagrams By Number
Normal Operation
The oil pressure switch is hardwired to the Instrument Panel Cluster (IPC) and is a normally open switch. With engine oil pressure, the oil pressure switch closes to ground and opens without oil pressure.
Non-Hybrid
The IPC provides a reference voltage to the engine oil pressure switch. When the oil pressure is within normal ranges, the engine oil pressure switch closes to ground, pulling the reference voltage low in the IPC. With the oil pressure switch closed, the IPC senses the low reference voltage and turns off the low oil pressure message center warning indicator. When the engine oil pressure is low, the engine oil pressure switch opens, sending the reference voltage high in the IPC. The IPC senses the high voltage and turns on the low oil pressure message center warning indicator.
Hybrid
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
PINPOINT TEST AQ: THE LOW OIL PRESSURE MESSAGE CENTER WARNING INDICATOR IS NEVER/ALWAYS ON
NOTICE: Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may damage the connector.
NOTE: Failure to disconnect the battery when instructed will result in false resistance readings. Refer to Battery.
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AQ1 CHECK THE MESSAGE CENTER OPERATION
- Close all doors and the luggage compartment lid.
- Ignition ON.
- Open the driver door while monitoring the message center displays.
- Does the message center display the door ajar message center warning indicator along with the DRIVER DOOR AJAR text?
Yes
For Hybrid, GO to AQ2.
For non-Hybrid, if the original symptom is the low oil pressure warning indicator is never on, GO to AQ4.
For non-Hybrid, if the original symptom is the low oil pressure warning indicator is always on, GO to AQ6.
No
INSTALL a new IPC. REFER to Instrument Panel Cluster (IPC) Instrument Panel Cluster (IPC). TEST the system for normal operation.
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AQ2 CHECK THE TACHOMETER
- Set the message center to enlighten display mode.
- Start the engine and observe the tachometer.
- Is rpm present and above 500 rpm on the tachometer?
Yes
If the original symptom is the low oil pressure indicator is on with the engine off and the vehicle in electric vehicle mode, GO to AQ3.
If the original symptom is the low oil pressure warning indicator is always on, GO to AQ6.
If the original symptom is the low oil pressure warning indicator is never on, GO to AQ4.
No
GO to Pinpoint Test I. Pinpoint Test I: The Tachometer Is Inoperative
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AQ3 RETRIEVE THE RECORDED DTCs FROM THE IPC SELF-TEST
- Check for recorded DTCs from the IPC self-test.
- Is DTC U0100:00 recorded?
Yes
GO to Pinpoint Test BF. Pinpoint Tests BF: DTC U0100:00
No
INSTALL a new IC. REFER to Instrument Panel Cluster (IPC) Instrument Panel Cluster (IPC). TEST the system for normal operation.
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AQ4 CHECK FOR A STUCK CLOSED ENGINE OIL PRESSURE SWITCH
- Ignition OFF.
- Disconnect: Engine Oil Pressure Switch C103 .
- Start the engine.
- Observe the low oil pressure warning indicator.
- Does the low oil pressure warning indicator turn on?
Yes
INSTALL a new Engine Oil Pressure (EOP) switch. REFER to Engine. TEST the system for normal operation.
No
GO to AQ5.
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AQ5 CHECK OIL PRESSURE INPUT CIRCUIT FOR A SHORT TO GROUND
- Ignition OFF.
- Disconnect: IPC C220 .
- For the non-Hybrid, measure the resistance between the IPC C220-6, circuit CMC24 (GY), harness side and ground.
- For the Hybrid, measure the resistance between the IPC C220-8, circuit CMC24 (GY), harness side and ground.
- Is the resistance greater than 10,000 ohms?
Yes
GO to AQ9.
No
REPAIR the circuit. TEST the system for normal operation.
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AQ6 CHECK FOR A STUCK OPEN ENGINE OIL PRESSURE SWITCH
- Ignition OFF.
- Disconnect: Engine Oil Pressure Switch C103 .
- Connect a fused jumper wire between the engine oil pressure switch, C103-1, circuit CMC24 (GY), harness side and ground.
- Start the engine.
- Observe the low oil pressure warning indicator.
- Does the low oil pressure warning indicator turn off?
Yes
REMOVE the jumper wire. GO to AQ8.
No
LEAVE the jumper wire connected. GO to AQ7.
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AQ7 CHECK OIL PRESSURE INPUT CIRCUIT FOR AN OPEN
- Ignition OFF.
- Disconnect: Negative Battery Cable .
- Disconnect: IPC C220 .
- For the non-Hybrid, measure the resistance between the IPC C220-6, circuit CMC24 (GY), harness side and ground.
- For the Hybrid, measure the resistance between the IPC C220-8, circuit CMC24 (GY), harness side and ground.
- Is the resistance less than 5 ohms?
Yes
REMOVE the jumper wire. GO to AQ9.
No
REMOVE the jumper wire. REPAIR the circuit. TEST the system for normal operation.
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AQ8 CHECK THE OIL PRESSURE
- Carry out the oil pressure test. Refer to Engine. Oil Pressure Test
- Is the oil pressure within specification?
Yes
INSTALL a new Engine Oil Pressure (EOP) switch. REFER to Engine. TEST the system for normal operation.
No
REFER to Engine to continue diagnosis of the low engine oil pressure concern.
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AQ9 CHECK FOR CORRECT IPC OPERATION
- Disconnect the IPC connector.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect the IPC connector and make sure it seats correctly.
- Operate the system and verify the concern is still present.
- Is the concern still present?
Yes
INSTALL a new IPC. REFER to Instrument Panel Cluster (IPC) Instrument Panel Cluster (IPC). TEST the system for normal operation.
No
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector.
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