Pinpoint Test L: The Low Oil Pressure Warning Indicator Is Never/Always On
Instrumentation, Message Center and Warning Chimes
Pinpoint Tests
Pinpoint Test L: 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 Instrument Panel Cluster (IPC) provides a reference voltage to the engine oil pressure switch through the 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 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 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
- IPC
PINPOINT TEST L: THE LOW OIL PRESSURE 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.
-------------------------------------------------
L1 CARRY OUT THE IPC INDICATOR LAMP CONTROL ACTIVE COMMAND USING THE SCAN TOOL
- Ignition ON.
- Enter the following diagnostic mode on the scan tool: IPC DataLogger .
- Select the IPC low oil pressure warning indicator (OIL_P_LOW) active command. Command the low oil pressure warning indicator on and off while observing 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 always on, GO to L4.
If the low oil pressure warning indicator is never on, GO to L2.
No
GO to L7.
-------------------------------------------------
L2 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. REFER to Engine - 4.6L (2V) Service and Repair, Engine - 5.4L (2V) Service and Repair or Engine - 6.8L Service and Repair. TEST the system for normal operation.
No
GO to L3.
-------------------------------------------------
L3 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 L7.
No
REPAIR the circuit. TEST the system for normal operation.
-------------------------------------------------
L4 CHECK FOR A STUCK OPEN ENGINE OIL PRESSURE SWITCH
NOTE: If the fused jumper wire fails, repair circuit CMC24 (GY) for a short to voltage.
- 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 L6.
No
LEAVE the jumper wire connected. GO to L5.
-------------------------------------------------
L5 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 L7.
No
REMOVE the jumper wire. REPAIR the circuit. TEST the system for normal operation.
-------------------------------------------------
L6 CHECK THE OIL PRESSURE
- Carry out the oil pressure test. Refer to Engine System - General Information Oil Pressure Test.
- Is the oil pressure within specification?
Yes
INSTALL a new 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 low engine oil pressure concern.
-------------------------------------------------
L7 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.
-------------------------------------------------