Pinpoint Tests AB: The Low Oil Pressure Warning Indicator Is Never/Always On

Instrumentation, Message Center and Warning Chimes

Pinpoint Tests

Pinpoint Test AB: The Low Oil Pressure Warning Indicator Is Never/Always On (Gasoline Only)

Refer to Wiring Diagram Set 60, Instrument Cluster for schematic and connector information. Diagrams By Number

Normal Operation

The Instrument Cluster (IC) 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 IC. The IC senses the low reference voltage and turns off the low oil pressure warning indicator. When the engine oil pressure is low, the engine oil pressure switch opens, sending the reference voltage to the normal voltage in the IC. The IC senses the normal reference voltage and turns the low oil pressure warning indicator on.

This pinpoint test is intended to diagnose the following:

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



PINPOINT TEST AB: THE LOW OIL PRESSURE WARNING INDICATOR IS NEVER/ALWAYS ON (GASOLINE ONLY)

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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AB1 CARRY OUT THE IC INDICATOR LAMP CONTROL ACTIVE COMMAND USING THE SCAN TOOL


- Ignition ON.
- Enter the following diagnostic mode on the scan tool: IC DataLogger .
- Select the IC low oil pressure warning indicator (OIL_P_LOW) active command. Command the low oil pressure warning indicator on and off. Observe the low oil pressure warning indicator.
- Does the low oil pressure warning indicator illuminate when commanded on and turn off when commanded off?

Yes
If the low oil pressure warning indicator is never on, GO to AB2.

If the low oil pressure warning indicator is always on, GO to AB4.

No
INSTALL a new IC. REFER to Instrument Cluster (IC) Instrument Cluster (IC). TEST the system for normal operation.

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AB2 CHECK FOR A STUCK CLOSED ENGINE OIL PRESSURE SWITCH


- Ignition OFF.
- Disconnect: Engine Oil Pressure Switch C103 .
- Ignition ON.
- 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. For gasoline engines, REFER to Engine.

For diesel engine, REFER to Computers and Control Systems. TEST the system for normal operation

No
GO to AB3.

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AB3 CHECK THE OIL PRESSURE INPUT CIRCUIT FOR A SHORT TO GROUND


- Ignition OFF.
- Disconnect: IC C220 .
- Measure the resistance between the IC C220-22, circuit CMC24 (GY), harness side and ground.




- Is the resistance greater than 10,000 ohms?

Yes
GO to AB7.

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

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AB4 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 warning indicator.
- Does the low oil pressure warning indicator turn off?

Yes
REMOVE the jumper wire. GO to AB6.

No
LEAVE the jumper wire connected. GO to AB5.

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AB5 CHECK THE OIL PRESSURE INPUT CIRCUIT FOR AN OPEN


- Ignition OFF.
- Disconnect: Negative Battery Cable .
- Disconnect: IC C220 .
- With the jumper wire in place, measure the resistance between the IC C220-22, circuit CMC24 (GY), harness side and ground.




- Is the resistance less than 5 ohms?

Yes
REMOVE the jumper wire. GO to AB7.

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

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AB6 CHECK THE OIL PRESSURE


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

Yes
INSTALL a new Engine Oil Pressure (EOP) switch. For gasoline engines, REFER to Engine.

For diesel engine, REFER to Computers and Control Systems. TEST the system for normal operation

No
REFER to Engine to continue diagnosis of the engine oil pressure.

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AB7 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). 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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