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Home >> GMC >> 2018 >> Acadia Denali, FWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 167 (Engine Controls And Fuel - 3.6L (LGX LF4) - DTC P0650 To DTC P3436 And Diagnostic Information And Procedures) >> Diagnostic Information and Procedures >> DTC P15A1: Fuel Economy Mode Switch Performance (LGX or LF4 Automatic) >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different car, the 2017 Cadillac ATS. However, it is still accessible from the selected car via links, so may be relevant.
NOTE:

You must perform the Circuit/System Verification before proceeding with Circuit/System Testing.

  1. Ignition OFF and all vehicle systems OFF, It may take up to 2 minutes for all vehicle systems to power down.
  2. Disconnect the X1 harness connector at the S126 Drive Mode Select switch.
  3. Test for less than 5 Ω between the ground circuit terminal 9 of the harness connector and ground.
    • If 5 Ω or greater 

      Repair the open/high resistance in the circuit.

    • If less than 5 Ω 
  4. Disconnect the X1 harness connector at the engine control module (ECM).
  5. Test for less than 5 Ω in the 5 V reference voltage circuit end to end.
    • If 5 Ω or greater 

      Repair the open/high resistance in the 5 V reference voltage circuit.

    • If less than 5 Ω 
  6. Test for less than 5 Ω in the signal circuit end to end.
    • If 5 Ω or greater 

      Repair the open/high resistance in the signal circuit.

    • If less than 5 Ω 
  7. Replace the K20 ECM.