Pinpoint Test N: The Low Oil Pressure Warning Indicator Is Never/Always On

Instrumentation, Message Center and Warning Chimes

Pinpoint Tests

Pinpoint Test N: The Low Oil Pressure 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 engine oil pressure switch is hardwired to the Instrument Cluster (IC). When the oil pressure is within normal ranges, the engine oil pressure switch closes and grounds the engine oil pressure input circuit to the IC, turning off the low oil pressure warning indicator. When engine oil pressure is low, the engine oil pressure switch opens, removing the ground to the IC, turning on the low oil pressure warning indicator.

This pinpoint test is intended to diagnose the following:

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



PINPOINT TEST N: THE LOW OIL PRESSURE 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.

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N1 DETERMINE THE CONDITION


- Start the engine.
- Observe the low oil pressure indicator.
- Is the low oil pressure indicator illuminated?

Yes
GO to N2.

No
GO to N5.

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N2 CHECK THE LOW OIL PRESSURE INDICATOR OPERATION


NOTE: If the fused jumper wire fails, refer to the Wiring Diagrams to identify the possible cause of the circuit short. Diagrams By Number

- Ignition OFF.
- Disconnect: Engine Oil Pressure Switch C103.
- Connect a fused jumper wire between the engine oil pressure switch C103-1, circuit CMC24 (GY) (4.6L) or circuit CMC24 (WH/RD) (4.0L), harness side and ground.




- Ignition ON.
- Does the low oil pressure indicator continue to illuminate?

Yes
REMOVE the jumper wire. GO to N3.

No
REMOVE the jumper wire. GO to N4.

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N3 CHECK THE OIL PRESSURE INPUT CIRCUIT FOR AN OPEN


- Ignition OFF.
- Disconnect: IC C220.
- Measure the resistance between the IC C220-18, circuit CMC24 (GY), and the engine oil pressure switch C103-1, circuit CMC24 (GY), harness side and ground.




- Is the resistance less than 5 ohms?

Yes
GO to N7.

No
REPAIR circuit CMC24 (GY) for an open. TEST the system for normal operation.

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N4 CARRY OUT THE ENGINE OIL PRESSURE TEST


- Ignition OFF.
- Carry out the engine oil pressure test. Refer to Engine. Oil Pressure Test
- Is the engine oil pressure within specification?

Yes
INSTALL a new oil pressure switch. TEST the system for normal operation.

No
REFER to Engine.

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N5 CARRY OUT THE IC PROVE OUT


- Ignition OFF.
- Disconnect: Engine Oil Pressure Switch C103.
- Ignition ON.
- Wait until the IC carries out the bulb prove out while observing the low oil pressure indicator.
- Does the low oil pressure indicator illuminate after the IC prove out?

Yes
INSTALL a new engine oil pressure switch. TEST the system for normal operation.

No
GO to N6.

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N6 CHECK THE ENGINE OIL PRESSURE INPUT CIRCUIT FOR A SHORT TO GROUND


- Ignition OFF.
- Disconnect: IC C220.
- Ignition ON.
- Measure the resistance between the IC C220-18, circuit CMC24 (GY), harness side and ground.




- Is the resistance than greater than 10,000 ohms?

Yes
GO to N7.

No
REPAIR circuit CMC24 (GY) for a short to ground. TEST the system for normal operation.

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N7 CHECK FOR CORRECT IC OPERATION


- Disconnect the IC connector.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect the IC 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 IC. REFER to Instrument Cluster (IC) Instrument Cluster (IC).

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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