Pinpoint Test D: Incorrect Oil Pressure Gauge Indication
Instrumentation, Message Center and Warning Chimes
Pinpoint Tests
Pinpoint Test D: 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) communication bus.
The PCM provides a reference voltage to the engine oil pressure switch when the ignition key is in the RUN position. 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 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 to command the oil pressure gauge to the normal oil pressure range.
If the IPC fails to receive the oil pressure status from the PCM for 5 seconds or less, the IPC defaults the oil pressure gauge to the last setting, based upon the last known good oil pressure status message. If the IPC fails to receive the oil pressure status from the PCM for more than 5 seconds, the IPC sets DTC U0100:00 in continuous memory and defaults the oil pressure gauge to low (L).
- DTC P1678 (Low Oil Pressure Lamp Control Circuit) - sets in the PCM if the oil pressure status indicates oil pressure is present with engine off for 2 seconds.
NOTE: If DTC U0100:00 sets in the IPC, 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
- Engine oil pressure switch
- Base engine oil pressure concern
- PCM
- IPC
PINPOINT TEST D: 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.
NOTE: Failure to disconnect the battery when instructed results in false resistance readings. Refer to Battery, Mounting and Cables Battery Disconnect / Connect.
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D1 CARRY OUT THE IPC OIL PRESSURE GAUGE ACTIVE COMMAND USING THE SCAN TOOL
- Ignition ON.
- Enter the following diagnostic mode on the scan tool: IPC DataLogger.
- Select the IPC 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 D2. If the oil pressure gauge always reads low (L) and does not register any oil pressure, GO to D4.
No
INSTALL a new IPC. REFER to Instrument Panel Cluster (IPC) Instrument Panel Cluster (IPC). TEST the system for normal operation.
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D2 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. For gasoline engines, REFER to Engine . TEST the system for normal operation. For diesel engine, REFER to Electronic Engine Controls - Diesel Engine Service and Repair. TEST the system for normal operation.
No
GO to D3.
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D3 CHECK THE OIL PRESSURE INPUT CIRCUIT FOR A SHORT TO GROUND
- Ignition OFF.
- Disconnect: PCM C175e (Gasoline) or C1232e (Diesel).
- For gasoline engines, measure the resistance between the PCM C175e-24, circuit CMC24 (GY), harness side and ground.
- For the diesel engine, measure the resistance between the PCM C1232e-56, circuit CMC24 (GY), harness side and ground.
- Is the resistance greater than 10,000 ohms?
Yes
GO to D8.
No
REPAIR circuit CMC24 (GY) for a short to ground. TEST the system for normal operation.
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D4 RETRIEVE THE RECORDED DTCs FROM THE IPC SELF-TEST
- Check for recorded IPC DTCs from the self-test.
- Is DTC U0100:00 recorded?
Yes
GO to Pinpoint Test BA. Pinpoint Tests BA: DTC U0100:00
No
GO to D5.
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D5 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 D7.
No
LEAVE the jumper wire connected. GO to D6.
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D6 CHECK THE ENGINE OIL PRESSURE INPUT CIRCUIT FOR AN OPEN
- Ignition OFF.
- Disconnect: Negative Battery Cable.
- Disconnect: C175e (Gasoline) or C1232e (Diesel).
- For gasoline engines, with the jumper wire in place measure the resistance between the PCM C175e-24, circuit CMC24 (GY), harness side and ground.
- For the diesel engine, with the jumper wire in place measure the resistance between the PCM C1232e-56, circuit CMC24 (GY), harness side and ground.
- Is the resistance less than 5 ohms?
Yes
REMOVE the jumper wire. GO to D8.
No
REMOVE the jumper wire. REPAIR circuit CMC24 (GY) for an open. TEST the system for normal operation.
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D7 CHECK THE OIL PRESSURE
- Carry out the engine oil pressure test. Refer to Engine System - General Information Oil Pressure Test.
- Is the oil pressure within specification?
Yes
INSTALL a new engine oil pressure switch. For gasoline engines, REFER to Engine . TEST the system for normal operation. For diesel engine, REFER to Electronic Engine Controls - Diesel Engine Service and Repair. TEST the system for normal operation.
No
REFER to Engine System - General Information Testing and Inspection to continue diagnosis of the engine oil pressure.
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D8 RETRIEVE THE RECORDED DTCs FROM THE PCM KOEO SELF-TEST
- Connect: Engine Oil Pressure Switch C103.
- Connect: C175e (Gasoline) or C1232e (Diesel).
- 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 D9.
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D9 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. REFER to Electronic Engine Controls Powertrain Control Module (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.
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