Pinpoint Test Z: The Low Oil Pressure Message Center Warning Indicator Is Never/Always On
Instrumentation, Message Center and Warning Chimes
Pinpoint Test Z: The Low Oil Pressure Message Center Warning Indicator Is Never/Always On
Normal Operation
The engine oil pressure switch is hardwired to the PCM. The Instrument Panel Cluster (IPC) receives the engine oil pressure status from the PCM over the High Speed Controller Area Network (HS-CAN). The IPC (Instrument Panel Cluster) uses both the messaged oil pressure status and engine rpm to control the low oil pressure message center warning indicator. The PCM provides a reference voltage to the engine oil pressure switch when the ignition key is in the RUN position. With the engine running and low or no oil pressure, the engine oil pressure switch remains open. The PCM detects no change in the reference voltage and provides the IPC (Instrument Panel Cluster) a request to illuminate the low oil pressure warning indicator. With the engine running and sufficient oil pressure, the engine oil pressure switch closes, pulling the reference voltage low. The PCM detects the low reference voltage and provides the IPC (Instrument Panel Cluster) a request to turn off the low oil pressure warning indicator.
NOTE: On early build vehicles, multiple ignition ON/OFF cycles may result in the low oil pressure message center warning indicator to display in the message center with the ignition in the ON mode and the engine off. The engine must be running to validate the operation of the low oil pressure message center warning indicator.
If the IPC (Instrument Panel Cluster) fails to receive the oil pressure status from the PCM for less than 5 seconds, the IPC (Instrument Panel Cluster) defaults the low oil pressure warning indicator to the last state (on or off), based upon the last known good oil pressure status message. If the IPC (Instrument Panel Cluster) fails to receive the oil pressure status from the PCM for 5 seconds or longer, the IPC (Instrument Panel Cluster) sets DTC U0100:00 in continuous memory and defaults the low oil pressure warning indicator active (on).
NOTE: If DTC U0100:00 sets in the IPC (Instrument Panel Cluster), other observable symptoms may be an inoperative speedometer, tachometer, temperature gauge or odometer.
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- Tachometer concern
- Engine oil pressure switch
- Base engine concern
- PCM
- IPC (Instrument Panel Cluster)
PINPOINT TEST Z : 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 results in false resistance readings.
Z1 VERIFY THE OPERATION OF THE TACHOMETER
- Ignition ON.
- With the engine running, verify the tachometer is operating correctly.
Does the tachometer operate correctly?
Yes
GO to Z2.
No
For an inoperative gauge, GO to Pinpoint Test F. Pinpoint Test F: The Tachometer Is Inoperative
For an incorrect gauge, GO to Pinpoint Test G. Pinpoint Test G: Incorrect Tachometer Indication
Z2 VERIFY THE OPERATION OF THE DOOR AJAR MESSAGE CENTER WARNING INDICATOR
- Close all doors then open the LH front door.
- NOTE: If multiple warnings are present, the message center cycles through each of the warnings. Allow the message center to cycle through each display while determining whether the door ajar message center warning indicator is active.
Observe the message center.
Is the door ajar message center warning indicator active?
Yes
If the low oil pressure message center warning indicator is never on, GO to Z3.
If the low oil pressure message center warning indicator is always on, GO to Z5.
No
INSTALL a new IPC (Instrument Panel Cluster). REFER to Instrument Panel Cluster (IPC) Service and Repair. TEST the system for normal operation.
Z3 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 illuminate?
Yes
INSTALL a new engine oil pressure switch. TEST the system for normal operation.
No
GO to Z4.
Z4 CHECK THE OIL PRESSURE INPUT CIRCUIT FOR A SHORT TO GROUND
- Ignition OFF.
- Disconnect: PCM C175E.
- Measure the resistance between the PCM C175E-13, circuit CMC24 (GY), harness side and ground.
Is the resistance greater than 10,000 ohms?
Yes
GO to Z9.
No
REPAIR circuit CMC24 (GY) for a short to ground. TEST the system for normal operation.
Z5 RETRIEVE THE RECORDED DTCs FROM THE IPC (Instrument Panel Cluster) SELF-TEST
- Check for recorded IPC (Instrument Panel Cluster) DTCs from the self-test.
Is DTC U0100:00 recorded?
Yes
GO to Pinpoint Test AQ. Pinpoint Test AQ: DTC U0100:00
No
GO to Z6.
Z6 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 indicator turn off?
Yes
REMOVE the jumper wire. GO to Z8.
No
LEAVE the jumper wire connected. GO to Z7.
Z7 CHECK THE ENGINE OIL PRESSURE INPUT CIRCUIT FOR AN OPEN
- Ignition OFF.
- Disconnect: Negative Battery Cable.
- Disconnect: C175E.
- Measure the resistance between the PCM C175E-13, circuit CMC24 (GY), harness side and ground.
Is the resistance less than 5 ohms?
Yes
REMOVE the jumper wire. GO to Z9.
No
REMOVE the jumper wire. REPAIR circuit CMC24 (GY) for an open. TEST the system for normal operation.
Z8 CHECK THE OIL PRESSURE
- Carry out the engine oil pressure test. Oil Pressure Test
Is the oil pressure within specification?
Yes
INSTALL a new engine oil pressure switch. TEST the system for normal operation.
No
REFER to Engine to continue diagnosis of the engine oil pressure.
Z9 RETRIEVE THE RECORDED DTCs FROM THE PCM KOEO (Key ON Engine OFF) SELF-TEST
- Check the recorded PCM DTCs from the Key ON Engine OFF (KOEO) self-test.
Are any DTCs recorded?
Yes
REFER to Computers and Control Systems Information.
No
GO to Z10.
Z10 CHECK FOR CORRECT PCM OPERATION
- Disconnect the PCM connectors.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect the PCM 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 PCM. 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.