Pinpoint Test C: Incorrect Oil Pressure Gauge Indication
Instrumentation, Message Center and Warning Chimes
Pinpoint Test C: Incorrect Oil Pressure Gauge Indication
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 PCM provides a reference voltage to the engine oil pressure switch when the ignition key is in RUN. When there is low or no oil pressure, the engine oil pressure switch remains open. The PCM detects no change in the reference voltage and provides engine oil pressure status to IPC (Instrument Panel Cluster) to keep the oil pressure gauge in the low oil pressure area of the gauge. 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 engine oil pressure status to the IPC (Instrument Panel Cluster) to command the oil pressure gauge to the normal oil pressure range.
If the IPC (Instrument Panel Cluster) fails to receive the oil pressure status from the PCM for 5 seconds or less, the IPC (Instrument Panel Cluster) defaults the oil pressure gauge to the last setting, 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 more than 5 seconds, the IPC (Instrument Panel Cluster) sets DTC U0100:00 in continuous memory and defaults the oil pressure gauge to low (L).
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:
- Communication network concern
- Wiring, terminals or connectors
- Engine oil pressure switch
- Base engine oil pressure concern
- PCM
- IPC (Instrument Panel Cluster)
PINPOINT TEST C : INCORRECT OIL PRESSURE GAUGE INDICATION
NOTICE: Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may damage the connector.
C1 CARRY OUT THE IPC (Instrument Panel Cluster) OIL PRESSURE GAUGE ACTIVE COMMAND USING THE SCAN TOOL
- Ignition ON.
- Enter the following diagnostic mode on the scan tool: IPC (Instrument Panel Cluster) DataLogger.
- Select the IPC (Instrument Panel Cluster) oil pressure gauge active command (OIL_PRESS) on and off to sweep the gauge.
Does the engine oil pressure gauge sweep to the normal range when commanded on and return to low (L) when commanded off?
Yes
If the oil pressure gauge always reads in the normal range, GO to C2.
If the oil pressure gauge always reads low (L) (does not register any oil pressure), GO to C4.
No
INSTALL a new IPC (Instrument Panel Cluster). REFER to Instrument Panel Cluster (IPC) . TEST the system for normal operation.
C2 CHECK FOR A STUCK CLOSED ENGINE OIL PRESSURE SWITCH
- Ignition OFF.
- Disconnect: Engine Oil Pressure Switch C103.
- Ignition ON.
- Observe the engine oil pressure gauge.
Does the engine oil pressure gauge indicate low (L) oil pressure?
Yes
INSTALL a new engine oil pressure switch. TEST the system for normal operation.
No
GO to C3.
C3 CHECK THE OIL PRESSURE INPUT CIRCUIT FOR A SHORT TO GROUND
- Ignition OFF.
- Disconnect: PCM C175E (3.7L), C1381E (5.0L and 6.2L), or C1551E (3.5L).
- For 3.5L, measure the resistance between the PCM C1551E-9, circuit CMC24 (GY), harness side and ground.
- For 3.7L, measure the resistance between the PCM C175E-13, circuit CMC24 (GY), harness side and ground.
- For 5.0L and 6.2L, measure the resistance between the PCM C1381E-24, circuit CMC24 (GY), harness side and ground.
Is the resistance greater than 10,000 ohms?
Yes
GO to C8.
No
REPAIR circuit CMC24 (GY) for a short to ground. TEST the system for normal operation.
C4 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 AT Pinpoint Test AT: DTC U0100:00.
No
GO to C5.
C5 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 engine oil pressure gauge.
Does the engine oil pressure gauge indicate normal oil pressure?
Yes
REMOVE the jumper wire. GO to C7.
No
LEAVE the jumper wire connected. GO to C6.
C6 CHECK THE ENGINE OIL PRESSURE INPUT CIRCUIT FOR AN OPEN
- Ignition OFF.
- Disconnect: PCM C175E (3.7L), C1381E (5.0L and 6.2L), or C1551E (3.5L).
- For 3.5L, measure the resistance between the PCM C1551E-9, circuit CMC24 (GY), harness side and ground.
- For 3.7L, measure the resistance between the PCM C175E-13, circuit CMC24 (GY), harness side and ground.
- For 5.0L and 6.2L, measure the resistance between the PCM C1381E-24, circuit CMC24 (GY), harness side and ground.
Is the resistance less than 5 ohms?
Yes
REMOVE the jumper wire. GO to C8.
No
REMOVE the jumper wire. REPAIR circuit CMC24 (GY) for an open. TEST the system for normal operation.
C7 CHECK THE ENGINE OIL PRESSURE
- Carry out the engine oil pressure test. Oil Pressure Test
Is the engine 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.
C8 RETRIEVE THE RECORDED DTCs FROM THE PCM KOEO (Key ON Engine OFF) SELF-TEST
- Connect: Engine Oil Pressure Switch C103.
- Connect: PCM C175E (3.7L), C1381E (5.0L and 6.2L) or C1551E (3.5L).
- 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. TEST the system for normal operation.
No
GO to C9.
C9 CHECK FOR CORRECT PCM OPERATION
- Disconnect the PCM connectors.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect the PCM connectors and make sure they seat 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.