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Home >> GMC >> 2014 >> Terrain SLT, 4D Utility >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls And Fuel - 3.6L (LFX) - DTC P0010 To DTC P0336 >> Diagnostic Information and Procedures >> DTC P0191 >> Circuit/System Testing

Circuit/System Testing

  1. Ignition OFF, all vehicle systems OFF, disconnect the B47B Fuel Rail Pressure Sensor connector. It may take up to 2 min for all vehicle systems to power down.
  2. Test for less than 5 Ω between the low reference circuit terminal C and ground.
    • If 5 Ω or greater 
    1. Ignition OFF, disconnect the X2 harness connector at the K20 Engine Control Module.
    2. Test for less than 2 Ω in the low reference circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, replace the K20 Engine Control Module.
    • If less than 5 Ω 
  3. Ignition ON.
  4. Test for 4.8-5.2 V between the 5 V reference circuit terminal A and ground.
    • If less than 4.8 V 
    1. Ignition OFF, disconnect the X2 harness connector at the K20 Engine Control Module.
    2. Test for infinite resistance between the 5 V reference circuit and ground.
      • If less than infinite resistance, repair the short to ground in the circuit.
      • If infinite resistance
    3. Test for less than 2 Ω in the 5 V reference circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, replace the K20 Engine Control Module.
    • If greater than 5.2 V 
    1. Ignition OFF, disconnect the X2 harness connector at the K20 Engine Control Module, ignition ON.
    2. Test for less than 1 V between the 5 V reference circuit and ground.
      • If 1 V or greater, repair the short to voltage on the circuit.
      • If less than 1 V, replace the K20 Engine Control Module.
    • If between 4.8-5.2 V 
  5. Verify the scan tool Fuel Rail Pressure Sensor voltage parameter is less than 0.02 V.
    • If 0.02 V or greater 
    1. Ignition OFF, disconnect the X2 harness connector at the K20 Engine Control Module, ignition ON.
    2. Test for less than 1 V between the signal circuit and ground.
      • If 1 V or greater, repair the short to voltage on the circuit.
      • If less than 1 V, replace the K20 Engine Control Module.
    • If less than 0.02 V 
  6. Connect a 3 A fused jumper wire between the signal circuit terminal B and the 5 V reference circuit terminal A.
  7. Verify the scan tool Fuel Rail Pressure Sensor Voltage parameter is greater than 4.96 V.
    • If 4.96 V or less 
    1. Ignition OFF, remove the fused jumper, disconnect the X2 harness connector at the K20 Engine Control Module.
    2. Test for infinite resistance between the signal circuit terminal 12 and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • If infinite resistance
    3. Test for less than 2 Ω in the signal circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, replace the K20 Engine Control Module.
    • If greater than 4.96 V 
  8. Test or replace the B47B Fuel Rail Pressure Sensor.
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