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Home › Hummer › 2009 › H3 Base, Automatic › Repair and Diagnosis › Transmission › Automatic Trans › Automatic Transmission - DTC P0218 To DTC P2771 › DTC P2771 › Circuit/System Testing

Circuit/System Testing

  1. If any other DTCs are set, diagnose them first. Refer to Diagnostic Trouble Code (DTC) List - Vehicle . Excessive slip in the transmission or transfer case or faulty speed sensors can cause DTC P2771 to set.
  2. Key Off. Disconnect the X1 connector at the ECM.
  3. Key ON. Engine OFF.
    4. NOTE: When test probing harness terminals, it is imperative to use the proper test probe from the most current version of the J 35616:  test kit. Use of an improper test probe may deform the terminal, resulting in intermittent open conditions.
  4. Test for B+ (+0.0/-1.5 V) between the Replicated TOS Signal circuit, ECM X1 Pin 71, and the ECM ground circuit, ECM X1 pin 73.
    • If the voltage is less than the specified range, test the Replicated TOS Signal circuit for an open/high resistance or short to ground. If all circuits and connections test normal, replace the TCM.
  5. Test for greater than 100 Ω between the Replicated TOS Signal circuit, ECM X1 Pin 71, and all other pins of the ECM X1.
    • If less than the specified range, test the affected circuits for a shorted together condition.
  6. Key Off. Disconnect the X1 connector at the TCM.
  7. Test for less than 1 Ω between the Replicated TOS Signal circuit, ECM X1 Pin 71, and the Replicated TOS Signal circuit, TCM X1 Pin 5.
    • If greater than the specified value, test the affected circuit for a open/high resistance condition.
  8. Connect the X1 connector at the ECM. Key ON. Engine OFF.
  9. Test for 2.0-3.0 V between the Replicated TOS Signal circuit, TCM X1 Pin 5, and the TCM ground circuit, TCM X1 pin 49.
    • If the voltage is greater than the specified range, test the Replicated TOS Signal circuit for a short to B+. If all circuits and connections test normal, replace the ECM.
    • If the voltage is less than the specified range, test the Replicated TOS Signal circuit for an open/high resistance or short to ground. If all circuits and connections test normal, replace the ECM.
  10. Test for greater than 100 Ω between the Replicated TOS Signal circuit, TCM X1 Pin 5, and all other pins of the ECM X1.
    • If less than the specified range, test the affected circuits for a shorted together condition.
  11. If all circuits and connections test normal go to Symptoms - Transfer Case .
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