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Home >> Hummer >> 2008 >> H2 4D Utility Wagon >> Repair and Diagnosis >> External Pages >> Different car >> Section 362 (Automatic Transmission - 6L80/6L90 - Diagnostic Information And Procedures) >> Diagnostic Information and Procedures >> DTC P2771 >> Circuit/System Testing

Circuit/System Testing

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  1. Remove connector from the transfer case control module. With ignition ON and engine OFF, observe with the scan tool the 4WD Low parameter.
    • If the scan tool indicates Enabled, test the 4WD Low signal circuit for a short to ground.
  2. Using the J 35616  GM-approved terminal test kit, install a fused jumper between the 4WD low signal circuit and ground at the transfer case control module connector.
    • If the scan tool 4WD Low parameter indicates Enabled when grounded, replace the transfer case control module.
  3. Test the 4WD Low signal circuit for an open.
    • Fix the open in the 4WD Low circuit.
  4. Replace the ECM.