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Pinpoint Test R: The Low Oil Pressure Warning Indicator Is Never/Always On

Refer to appropriate SYSTEM WIRING DIAGRAMS article, Instrument Cluster for schematic and connector information.

Normal Operation 

The instrument cluster (IC) provides a reference voltage to the engine oil pressure switch through circuit CMC24 (GY). When the oil pressure is within normal ranges, the engine oil pressure switch closes to ground, pulling the reference voltage low in the instrument cluster (IC). The instrument cluster (IC) senses the low voltage and turns off the low oil pressure warning indicator. When engine oil pressure is low, the engine oil pressure switch opens, removing the ground and sending the reference voltage back to the normal voltage in the instrument cluster (IC). The instrument cluster (IC) senses the reference voltage high and turns on the low oil pressure warning indicator.

This pinpoint test is intended to diagnose the following:

PINPOINT TEST R: THE LOW OIL PRESSURE WARNING INDICATOR IS NEVER/ALWAYS ON 

NOTE: Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may damage the connector.
  1. R1 CARRY OUT THE INSTRUMENT CLUSTER (IC) INDICATOR LAMP CONTROL ACTIVE COMMAND USING THE SCAN TOOL 
    • Key in ON position.
    • Enter the following diagnostic mode on the diagnostic tool: Instrument Cluster (IC) DataLogger
    • Select the instrument cluster (IC) low oil pressure warning indicator (OIL_P_LOW) active command and command the low oil pressure warning indicator on and off. Observe the low oil pressure warning indicator.
    • Does the low oil pressure warning indicator illuminate when commanded on, and turn off when commanded off? 
    1. YES  : If the low oil pressure warning indicator is always on, go to  R2.

      If the low oil pressure warning indicator is never on, go to  R5.

    2. NO  : Go to  R7.
  2. R2 MONITOR THE LOW OIL PRESSURE WARNING INDICATOR 
    • Key in OFF position.
    • Disconnect: Engine Oil Pressure Switch C103
    • Key in ON position.
      • Fig 1: Monitoring Low Oil Pressure Warning Indicator
      GF0018133Courtesy of FORD MOTOR CO.
    • Connect a fused (5A) jumper wire between the engine oil pressure switch C103-1, circuit CMC24 (GY), harness side and ground.
    • Does the low oil pressure warning indicator turn off with the jumper wire connected? 
    1. YES  : DISCONNECT the jumper wire. Go to  R3.
    2. NO  : DISCONNECT the jumper wire. Go to  R4.
  3. R3 CARRY OUT THE ENGINE OIL PRESSURE TEST 
    • Carry out the engine oil pressure test component test. Refer to ENGINE SYSTEM - GENERAL INFORMATION article component tests.
    • Is the engine oil pressure within specification? 
    1. YES  : INSTALL a new engine oil pressure (EOP) switch. REFER to ENGINE - 3.5L article. TEST the system for normal operation.
    2. NO  : REFER to ENGINE SYSTEM - GENERAL INFORMATION article.
  4. R4 CHECK CIRCUIT CMC24 (GY) FOR AN OPEN 
    • Key in OFF position.
    • Disconnect: Instrument Cluster (IC) C220
      • Fig 2: Measuring Resistance Between Instrument Cluster C220-8, Circuit CMC24 (GY) & Oil Pressure Switch C103-1
      GF0032217Courtesy of FORD MOTOR CO.
    • Measure the resistance between the instrument cluster (IC) C220-8, circuit CMC24 (GY), harness side and the oil pressure switch C103-1, circuit CMC24 (GY), harness side.
    • Is the resistance less than 5 ohms? 
    1. YES  : Go to  R7.
    2. NO  : REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test.
  5. R5 CHECK THE ENGINE OIL PRESSURE SWITCH 
    • Key in OFF position.
    • Disconnect: Oil Pressure Switch C103
    • Key in ON position.
    • Monitor the low oil pressure warning indicator.
    • Does the low oil pressure warning indicator illuminate? 
    1. YES  : INSTALL a new engine oil pressure (EOP) switch. REFER to ENGINE - 3.5L article. TEST the system for normal operation.
    2. NO  : Go to  R6.
  6. R6 CHECK CIRCUIT CMC24 (GY) FOR A SHORT TO GROUND 
    • Key in OFF position.
    • Disconnect: Instrument Cluster (IC) C220
      • Fig 3: Measuring Resistance Between Instrument Cluster C220-8, Circuit CMC24 (GY) & Ground
      GF0032218Courtesy of FORD MOTOR CO.
    • Measure the resistance between the instrument cluster (IC) C220-8, circuit CMC24 (GY), harness side and ground.
    • Is the resistance greater than 10,000 ohms? 
    1. YES  : Go to  R7.
    2. NO  : REPAIR the circuit. TEST the system for normal operation.
  7. R7 CHECK FOR CORRECT INSTRUMENT CLUSTER (IC) OPERATION 
    • Disconnect the instrument cluster (IC) connector.
    • Check for:
      • corrosion
      • damaged pins
      • pushed-out pins
    • Connect the instrument cluster (IC) connector and make sure it seats correctly.
    • Operate the system and verify the concern is still present.
    • Is the concern still present? 
    1. YES  : INSTALL a new instrument cluster (IC). REFER to Instrument Cluster (IC) . TEST the system for normal operation.
    2. 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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