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Home >> Lincoln >> 2019 >> Nautilus Base, FWD >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 5 (Automatic Transmission - 8-Speed Automatic Transmission - 8F57 (2 Of 2)) >> Diagnosis And Testing >> DTC Chart and Pinpoint Tests - 2.7L EcoBoost (238kW/324PS) >> Pinpoint Tests >> Pinpoint Test G : Transmission Fluid Pressure Sensor "A" And "B" DTCS

Pinpoint Test G : Transmission Fluid Pressure Sensor "A" And "B" DTCS

WARNING: This page is about a different variant/trim than selected.
  1. Refer to Transmission Controls - 8F57 for schematic and connector information.

    Normal Operation and Fault Conditions 

    Transmission Fluid Pressure (TFP) sensors for clutch A (TFP A) and B (TFP B) have been added to improve diagnostic capability for non-electrical (stuck solenoid or control valve) faults. The TFP sensors provide a voltage proportional to the absolute hydraulic pressure in the transmission clutch control circuit using a piezo-resistive silicon sensing element. Pressure readings are used to monitor the status of specified clutch systems during operation. The typical operating output range is 0.5V to 4.5V. The pressure sensor is typically mounted on the transmission main control assembly with a dedicated feed port. TFP A sensor measures A clutch pressure, TFP B sensor measures B clutch pressure.

    DTC Fault Trigger Conditions 

    DTC Description Fault Trigger Condition
    PCM P0840:00 Transmission Fluid Pressure Sensor/Switch "A" Circuit: No Sub Type Information This DTC sets if the PCM detects a circuit fault on TFP A. It sets with DTCs P0842 or P0843, and is used to light the wrench light.
    PCM P0841:00 Transmission Fluid Pressure Sensor/Switch "A" Circuit Range/Performance: No Sub Type Information This DTC sets if clutch A applies and releases as commanded, but the measured pressure from TFP A does not follow the commanded pressure for clutch A. Measured pressure is stuck high or low while clutch A applies and releases as commanded (as measured by speed sensors).
    PCM P0842:00 Transmission Fluid Pressure Sensor/Switch "A" Circuit Low: No Sub Type Information This DTC sets if the PCM detects that TFP A sensor voltage is out of range low.
    PCM P0843:00 Transmission Fluid Pressure Sensor/Switch "A" Circuit High: No Sub Type Information This DTC sets if the PCM detects that TFP A sensor voltage is out of range high.
    PCM P0845:00 Transmission Fluid Pressure Sensor/Switch "B" Circuit: No Sub Type Information This DTC sets if the PCM detects a circuit fault on TFP B. It sets with P0847 or P0848, and is used to light the wrench light.
    PCM P0846:00 Transmission Fluid Pressure Sensor/Switch "B" Circuit Range/Performance: No Sub Type Information This DTC sets if the PCM detects the B clutch is stuck off due to a non-electrical fault. Multiple attempts to apply the B clutch have failed.
    PCM P0847:00 Transmission Fluid Pressure Sensor/Switch "B" Circuit Low: No Sub Type Information This DTC sets if the PCM detects that TFP B sensor voltage is out of range low.
    PCM P0848:00 Transmission Fluid Pressure Sensor/Switch "B" Circuit High: No Sub Type Information This DTC sets if clutch B applies and releases as commanded, but the measured pressure from TFP B does not follow the commanded pressure for clutch B. Measured pressure is stuck high or low while clutch B applies and releases as commanded (as measured by speed sensors).

    Possible Sources 

    • Connectors damaged or pushed-out terminals, corrosion, loose wires and missing or damaged seals
    • Transmission fluid pressure sensor
    • Contamination in the main control
    • Damaged A or B clutch

  2. G1 CHECK FOR ELECTRICAL DTCS

    • Connect the diagnostic tool.

    • Using a diagnostic scan tool perform self-test.

    Are any electrical circuit DTCs for the transmission fluid pressure sensor retrieved? 

    Yes  GO to  G6
    No  GO to  G2

  3. G2 CHECK FOR OBSERVABLE SYMPTOMS

    • Using a diagnostic scan tool, CLEAR the DTCs.

    • Shift the selector lever from Reverse to Drive to Neutral and back to Park.

    Are any observable symptoms present? 

    Yes  REFER to: Diagnosis By Symptom  .
    No  GO to  G3

  4. G3 CHECK THE "A" AND "B" CLUTCH ENGAGEMENT STATE IN PARK

    • Ignition ON.

    • Clear DTCs.

    • Enter the following diagnostic mode: Datalogger.

    • Monitor the PIDS TFP_A, TFP_B and TSS_SRC.

    • Select NEUTRAL.

    • Start the engine.

    Are the PIDs TFP_A, TFP_B voltages below 0.6 volts and does the PID TSS_SRC show turbine shaft speed above 300 RPM? 

    Yes  GO to  G4
    No  INSTALL a new transmission fluid pressure sensor. REFER to: Main Control Valve Body  .

  5. G4 CHECK THE "A" CLUTCH ENGAGEMENT STATE IN FIRST GEAR

    • Monitor the PIDs TFP_A and TSS.

    • Select FIRST.

    Is the TFP A voltage between 1.0 volts and 2.0 and the PID TSS_SRC show turbine shaft speed approximately 0 RPM? 

    Yes  GO to  G5
    No  INSTALL a new transmission fluid pressure sensor. REFER to: Main Control Valve Body  .v

  6. G5 CHECK THE "B" CLUTCH ENGAGEMENT STATE IN REVERSE

    • Monitor the PIDS TFP B and TSS_SRC.

    • Select REVERSE.

    Is the TFP B voltage between 1.0 volts and 2.0 volts and the PID TSS_SRC show turbine shaft speed approximately 0 RPM? 

    Yes  Both the A and B clutches are operating correctly at this time. Road test the vehicle and if any observable symptoms are present,
    No  INSTALL a new transmission fluid pressure sensor. REFER to: Main Control Valve Body  .

  7. G6 CHECK TRANSMISSION FLUID PRESSURE SENSOR CIRCUIT FOR POWER

    • Ignition OFF.

    • Disconnect Transmission Vehicle Harness C1575.

    • Ignition ON.

    • Measure:
      Positive Lead Measurement / Action Negative Lead
      C1575-1
      GFD425661Courtesy of FORD MOTOR COMPANY
      		 Ground

    Is the voltage approximately 5 volts? 

    Yes  GO to  G9
    No  GO to  G7

  8. G7 CHECK TRANSMISSION FLUID PRESSURE SENSOR CIRCUITS FOR AN OPEN

    • Disconnect PCM C1551T.

    Are the resistances less than 3 ohms? 

    Yes  GO to  G8
    No  REPAIR the circuit.

  9. G8 CHECK TRANSMISSION FLUID PRESSURE SENSOR CIRCUITS FOR A SHORT TO GROUND

    • Measure:
      Positive Lead Measurement / Action Negative Lead
      C1575-1
      GFD425660Courtesy of FORD MOTOR COMPANY
      		 Ground
      C1575-20
      GFD425660Courtesy of FORD MOTOR COMPANY
      		 Ground
      C1575-21
      GFD425660Courtesy of FORD MOTOR COMPANY
      		 Ground
      C1575-14
      GFD425660Courtesy of FORD MOTOR COMPANY
      		 Ground

    Are the resistances greater than 10, 000 ohms? 

    Yes  GO to  G9
    No  REPAIR the circuit.

  10. G9 CHECK TRANSMISSION INTERNAL WIRING HARNESS FOR AN OPEN CIRCUIT

    • Measure:
      Positive Lead Measurement / Action Negative Lead
      GFD427715Courtesy of FORD MOTOR COMPANY

      Transmission Harness Connector, component side, pin 14
      GFD425660Courtesy of FORD MOTOR COMPANY
      		 C1792-1
      GFD427715Courtesy of FORD MOTOR COMPANY

      Transmission Harness Connector, component side, pin 21
      GFD425660Courtesy of FORD MOTOR COMPANY
      		 C1792-2
      GFD427715Courtesy of FORD MOTOR COMPANY

      Transmission Harness Connector, component side, pin 20
      GFD425660Courtesy of FORD MOTOR COMPANY
      		 C1792-3
      GFD427715Courtesy of FORD MOTOR COMPANY

      Transmission Harness Connector, component side, pin 1
      GFD425660Courtesy of FORD MOTOR COMPANY
      		 C1792-4

    Are the resistances less than 3 ohms? 

    Yes  GO to  G10
    No  REPAIR the suspect circuit.

  11. G10 CHECK TRANSMISSION INTERNAL WIRING HARNESS FOR A SHORT TO GROUND

    • Measure:
      Positive Lead Measurement / Action Negative Lead
      GFD427715Courtesy of FORD MOTOR COMPANY

      Transmission Harness Connector, component side, pin 14
      GFD425660Courtesy of FORD MOTOR COMPANY
      		 Ground
      GFD427715Courtesy of FORD MOTOR COMPANY

      Transmission Harness Connector, component side, pin 21
      GFD425660Courtesy of FORD MOTOR COMPANY
      		 Ground
      GFD427715Courtesy of FORD MOTOR COMPANY

      Transmission Harness Connector, component side, pin 20
      GFD425660Courtesy of FORD MOTOR COMPANY
      		 Ground
      GFD427715Courtesy of FORD MOTOR COMPANY

      Transmission Harness Connector, component side, pin 1
      GFD425660Courtesy of FORD MOTOR COMPANY
      		 Ground

    Are the resistances greater than 10, 000 ohms? 

    Yes  INSTALL a new transmission fluid pressure sensor. REFER to: Main Control Valve Body  .
    No  INSTALL a new internal wiring harness. REFER to: Main Control Valve Body  .
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