Pinpoint Test L: The Engine Oil Pressure Warning Indicator Is Never/Always On

L1 CHECK THE OIL PRESSURE SWITCH OPERATION
- Key in OFF position.
- Disconnect: Engine Oil Pressure Switch C103.
- Connect a fused (10A) jumper wire between the engine oil pressure switch C103, circuit 31S-GC20 (BK/OG), harness side and ground.
  
  Fig 1: Connecting Fused (10A) Jumper Wire Between Engine Oil Pressure Switch C103, Circuit 31S-GC20 (BK/OG), Harness Side And Ground
  Courtesy of FORD MOTOR CO.
- Key in ON position.
- Monitor the oil pressure warning indicator with the jumper wire connected and disconnected.
- Does the oil pressure warning indicator turn on with the jumper wire connected and turn off with the jumper wire disconnected?
  - Yes : GO to L2.
  - No : GO to L3.
L2 CARRY OUT THE ENGINE OIL PRESSURE TEST
- Carry out the engine oil pressure test. Refer to ENGINE SYSTEM-GENERAL INFORMATION .
- Is the engine oil pressure within specification?
  - Yes : INSTALL a new oil pressure switch. TEST the system for normal operation.
  - No : REFER to ENGINE SYSTEM-GENERAL INFORMATION to continue diagnosis of the engine lubrication system.
L3 CHECK CIRCUIT 31S-GC20 (BK/OG) FOR AN OPEN OR SHORT TO GROUND
- Key in OFF position.
- Disconnect: Instrument Cluster C2220.
- Measure the resistance between the instrument cluster C2220 pin 11, circuit 31S-GC20 (BK/OG), harness side and the engine oil pressure switch C103 pin 1, circuit 31S-GC20 (BK/OG), harness side; and between the instrument cluster C2220 pin 11, circuit 31S-GC20 (BK/OG), harness side and ground.
  
  Fig 2: Checking Circuit 31S-GC20 (BK/OG) For An Open Or Short To Ground
  Courtesy of FORD MOTOR CO.
- Is the resistance less than 5 ohms between the instrument cluster and the engine oil pressure switch, and greater than 10,000 ohms between the instrument cluster and ground?
  - Yes : GO to L4.
  - No : REPAIR the circuit. TEST the system for normal operation.
L4 CHECK CIRCUIT 31S-GC20 (BK/OG) FOR A SHORT TO POWER
- Key in ON position.
- Measure the voltage between the instrument cluster C2220 pin 11, circuit 31S-GC20 (BK/OG), harness side and ground.
  
  Fig 3: Measuring Voltage Between Instrument Cluster C2220 Pin 11, Circuit 31S-GC20 (BK/OG), Harness Side And Ground
  Courtesy of FORD MOTOR CO.
- Is any voltage present?
  - Yes : REPAIR the circuit. TEST the system for normal operation.
  - No : GO to L5.
L5 CHECK CIRCUIT 31S-GC20 (BK/OG) FOR A SHORT TO GROUND
- Key in OFF position.
- Measure the resistance between the instrument cluster C2220 pin 11, circuit 31S-GC20 (BK/OG), harness side and ground.
  
  Fig 4: Measuring Resistance Between Instrument Cluster C2220 Pin 11, Circuit 31S-GC20 (BK/OG), Harness Side And Ground
  Courtesy of FORD MOTOR CO.
- Is the resistance greater than 10,000 ohms?
  - Yes : REPAIR the circuit. TEST the system for normal operation.
  - No : GO to L6.
L6 CHECK FOR CORRECT INSTRUMENT CLUSTER OPERATION
- Disconnect the instrument cluster connector.
- Check for:
  - Corrosion
  - Pushed-out pins
- Connect the instrument cluster connector and make sure it seats correctly.
- Operate the system and determine if the concern is still present.
- Is the concern still present?
  - Yes : INSTALL a new instrument cluster. REFER to INSTRUMENT CLUSTER . 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. CLEAR the DTCs. TEST the system for normal operation.