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Pinpoint Test G : P1780 (Low Gear Select Switch)

  1. G1 RETRIEVE AND RECORD ALL DTCS

    • Ignition ON.

    • Connect the scan tool.

    • Using the diagnostic scan tool, retrieve all DTCs.

    • Start the engine.

    • Using the diagnostic scan tool, perform the KOER self-test

    Is DTC P1780 present? 

    Yes  GO to  G2.
    No  No trouble found with the low gear select system. REFER to Symptom Chart in Information Center - Instrumentation, Message Center, And Warning Chimes if the TCS lamp does not illuminate.

  2. G2 CHECK THE BCM FUSE

    • Ignition OFF.

    • Remove the BCM fuse 35 (5A).

    • Check the BCM fuse 35 (5A).

    Is the resistance less than 3 ohms? 

    Yes  GO to  G6.
    No  GO to  G3.

  3. G3 CHECK THE BCM FOR AN INTERNAL SHORT

    • Disconnect: BCM C2280B.

    • Inspect for damaged or pushed-out terminals.

    • Install a new fuse.

    Did the fuse fail? 

    Yes  Refer to BCM Guided Routine Testing .
    No  GO to  G4.

  4. G4 CHECK THE LOW GEAR SELECT SWITCH POWER CIRCUIT FOR A SHORT TO GROUND

    • Disconnect: Low Gear Select Switch C2804.

    • Measure the resistance  between.
      Positive Lead Negative Lead
      Pin Circuit Pin Circuit
      C2804-1 CBP35 (YE/GY) -- Ground

    Is the resistance greater than 10, 000 ohms? 

    Yes  GO to  G5.
    No  REPAIR the circuit.

  5. G5 CHECK THE LOW GEAR SELECT SWITCH SIGNAL INPUT CIRCUIT FOR A SHORT TO GROUND

    • Disconnect: PCM C1381B.

    • Measure the resistance  between.
      Positive Lead Negative Lead
      Pin Circuit Pin Circuit
      C2804-2 CET35 (BN) -- Ground

    Is the resistance greater than 10, 000 ohms? 

    Yes  GO to  G6.
    No  REPAIR the circuit.

  6. G6 CHECK THE LOW GEAR SELECT SWITCH POWER CIRCUIT FOR AN OPEN

    • Disconnect: Low Gear Select Switch C2804.

    • Disconnect: BCM C2280B.

    • Measure the resistance  between.
      Positive Lead Negative Lead
      Pin Circuit Pin Circuit
      C2804-1 CBP35 (YE/GY) C2280B-7 CBP35 (YE/GY)

    Is the resistance less than 3 ohms? 

    Yes  GO to  G7.
    No  REPAIR the circuit.

  7. G7 CHECK THE LOW GEAR SELECT SWITCH SIGNAL INPUT CIRCUIT FOR AN OPEN

    • Disconnect: PCM C1381B.

    • Measure the resistance  between.
      Positive Lead Negative Lead
      Pin Circuit Pin Circuit
      C2804-2 CET35 (BN) C1381B-90 CET35 (BN)

    Is the resistance less than 3 ohms? 

    Yes  GO to  G8.
    No  REPAIR the circuit.

  8. G8 CHECK THE LOW GEAR SELECT SWITCH

    • Measure the component side resistance  while cycling the low gear select switch between.
      Positive Lead Negative Lead
      Pin Circuit Pin Circuit
      1 -- 2 --

    Is the resistance less than 3 ohms when the switch is pressed and greater than 10, 000 ohms when released? 

    Yes  Refer to PCM Guided Routine Testing . PROGRAM the PCM with the latest calibration level. PERFORM the Solenoid Body Strategy Data Download procedure. REFER to Solenoid Body Strategy in Automatic Transaxle Transmission - 6F35 .
    No  INSTALL a new selector lever mechanism. REFER to Selector Lever Mechanism -- Column Shift . RUN the KOER self-test.
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