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Home >> GMC >> 2020 >> Terrain Denali, FWD >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 6 (Engine Controls And Fuel - 1.5L (LYX) - Diagnostic Information And Procedures (1 Of 2)) >> Diagnostic Information and Procedures >> DTC P0090-P0092, P00C8, P00C9, or P00CA (NTB) >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different variant/trim than selected.
  1. Ignition/Vehicle - Off
  2. Disconnect the electrical connector : G18 High Pressure Fuel Pump
  3. Connect a test lamp between the test points : Control circuit terminal 1 & Control circuit terminal 2
  4. Engine - Idling - At normal operating temperature
  5. Increase the engine speed slowly to 3500 RPM and then back to idle.
  6. Verify the test lamp turns On and changes brightness.
    • If the test lamp is always Off 
    1. Ignition/Vehicle - Off & Remove - Test lamp
    2. Disconnect the electrical connector : X3 @ K20 Engine Control Module
    3. Ignition - On / Vehicle - In Service Mode
    4. Test for less than 1 V between the test points :
      • Control circuit terminal 1 @ Component harness & Ground
      • Control circuit terminal 2 @ Component harness & Ground
      • If 1 V or greater - Repair the short to voltage on the circuit.
      • Go to next step : If less than 1 V
    5. Ignition/Vehicle - Off
    6. Test for infinite resistance between the test points :
      • Control circuit terminal 1 @ Component harness & Ground
      • Control circuit terminal 2 @ Component harness & Ground
      • If less than infinite resistance - Repair the short to ground on the circuit.
      • Go to next step : If infinite resistance
    7. Test for less than 2 ohms between the test points :
      • Control circuit terminal 1 @ Component harness & Terminal 32 @ Control module harness
      • Control circuit terminal 2 @ Component harness & Terminal 16 @ Control module harness
      • If 2 ohms or greater - Repair the open/high resistance in the circuit.
      • Go to next step : If less than 2 ohms
    8. Test for greater than 1 ohms between the test points : Control circuit terminal 1 & Control circuit terminal 2
      • If 1 ohms or less - Repair the short between the circuits.
      • If 1 ohms or greater - Replace the component : K20 Engine Control Module
    • Go to next step : If the test lamp turns On and changes brightness 
  7. Test or replace the component : G18 High Pressure Fuel Pump