Pinpoint Tests AF: The Low Oil Pressure Message Center Warning Indicator Is Never/Always On
Instrumentation, Message Center and Warning Chimes
Pinpoint Tests
Pinpoint Test AF: The Low Oil Pressure Message Center Warning Indicator Is Never/Always On
Refer to Wiring Diagram Set 60, Instrument Cluster for schematic and connector information. Diagrams By Number
Normal Operation
The Instrument Panel Cluster (IPC) provides a reference voltage to the engine oil pressure switch through the single input circuit. When the oil pressure is within normal ranges, the engine oil pressure switch closes to ground, pulling the reference voltage low in the IPC. 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 the low oil pressure message center warning indicator on after approximately 3.5 seconds.
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 AF: 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, Mounting and Cables Testing and Inspection.
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AF1 VERIFY THE OPERATION OF THE TACHOMETER
- Ignition ON.
- With the engine running, verify that the tachometer is operating.
- Does the tachometer operate?
Yes
GO to AF2.
No
GO to Pinpoint Test H. Pinpoint Test H: The Tachometer Is Inoperative
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AF2 VERIFY THE OPERATION OF THE POWERTRAIN MALFUNCTION (WRENCH) AND ENGINE OVER-TEMPERATURE MESSAGE CENTER INDICATORS
- Ignition OFF.
- Disconnect: PCM C175b (4.6L and 5.4L) or C1551 (6.8L) .
- Ignition ON.
- NOTE: If multiple warnings are present, the message center indicators rotate through each of the warnings. Allow the displays to rotate through each display while determining whether the powertrain malfunction (wrench) and over-temperature message center indicators are active.
- Observe the message center or integrated display area of the IPC with the PCM connected and disconnected.
- Does the powertrain malfunction (wrench) message center warning indicator remain off when the PCM is connected and become active with the PCM disconnected?
Yes
If the low oil pressure message center warning indicator is never on, GO to AF3.
If the low oil pressure message center warning indicator is always on, GO to AF5.
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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AF3 CHECK FOR A STUCK CLOSED ENGINE OIL PRESSURE SWITCH
- Ignition OFF.
- Connect: PCM C175b (4.6L and 5.4L) or C1551 (6.8L).
- Disconnect: Engine Oil Pressure Switch C103 .
- Start engine.
- NOTE: If multiple message center indicator on requests are present, the message center rotates through each of the message center indicator displays. Allow the message center to rotate through each display while determining whether the door ajar message center warning indicator is active.
- Observe the low oil pressure message center warning indicator.
- Is the low oil pressure message center warning indicator active or on?
Yes
INSTALL a new Engine Oil Pressure (EOP) switch.
REFER to Engine - 4.6L (2V) Service and Repair, Engine - 5.4L (2V) Service and Repair or Engine - 6.8L Service and Repair.
No
GO to AF4.
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AF4 CHECK THE INPUT CIRCUIT FOR A SHORT TO GROUND
- Ignition OFF.
- Disconnect: IPC C220 .
- Measure the resistance between the IPC C220-22, circuit CMC24 (GY), harness side and ground.
- Is the resistance greater than 10,000 ohms?
Yes
GO to AF8.
No
REPAIR the circuit. TEST the system for normal operation.
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AF5 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.
- Ignition ON.
- Observe the low oil pressure message center warning indicator.
- Does the low oil pressure message center warning indicator turn off?
Yes
REMOVE the jumper wire. GO to AF7.
No
LEAVE the jumper wire connected. GO to AF6.
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AF6 CHECK THE INPUT CIRCUIT FOR AN OPEN
- Ignition OFF.
- Disconnect: Negative Battery Cable .
- Disconnect: IPC C220 .
- With the jumper wire in place, measure the resistance between the IPC C220-22, circuit CMC24 (GY), harness side and ground.
- Is the resistance less than 5 ohms?
Yes
REMOVE the jumper wire. GO to AF8.
No
REMOVE the jumper wire. REPAIR the circuit. TEST the system for normal operation.
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AF7 CHECK THE OIL PRESSURE
- Carry out the engine oil pressure test. Refer to Engine System - General Information Oil Pressure Test.
- Is the oil pressure within specification?
Yes
INSTALL a new Engine Oil Pressure (EOP) switch. REFER to Engine - 4.6L (2V) Service and Repair, Engine - 5.4L (2V) Service and Repair or Engine - 6.8L Service and Repair.
No
REFER to Engine System - General Information Initial Inspection and Diagnostic Overview to continue diagnosis of the engine oil pressure.
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AF8 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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