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Home >> Chevrolet >> 2021 >> Trailblazer RS, 4WD >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 9 (Engine Controls And Fuel - 1.0L (L4B L4F L4G LIJ) Or 1.2L (L4H L4K LIF LIH) - Diagnostic Information And Procedures (1 Of 2)) >> Diagnostic Information and Procedures >> DTC P0201-P0203, P0261, P0262, P0264, P0265, P0267, P0268, P1248, P1249, P124A, P2147, P2148, P2150, P2151, P2153, or P2154 >> 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: X3 @ K20 Engine Control Module
  3. Test for infinite resistance between the test points:
    • {Q17A Fuel Injector 1} Control circuit terminal 72 & Ground
    • {Q17B Fuel Injector 2} Control circuit terminal 71 & Ground
    • {Q17C Fuel Injector 3} Control circuit terminal 70 & Ground
    • If less than infinite resistance 
    1. Disconnect the appropriate electrical connector: Q17 Fuel Injector
    2. Test for infinite resistance between the test points:
      • {Q17A Fuel Injector 1} Control circuit terminal 72 @ Control module harness & Ground
      • {Q17B Fuel Injector 2} Control circuit terminal 71 @ Control module harness & Ground
      • {Q17C Fuel Injector 3} Control circuit terminal 70 @ Control module harness & Ground
      • If less than infinite resistance - Repair the short to ground on the circuit.
      • Go to next step: If infinite resistance
    3. Test for infinite resistance between the test points:
      • {Q17A Fuel Injector 1} Control circuit terminal 52 @ Control module harness & Ground
      • {Q17B Fuel Injector 2} Control circuit terminal 51 @ Control module harness & Ground
      • {Q17C Fuel Injector 3} Control circuit terminal 50 @ Control module harness & Ground
      • If less than infinite resistance - Repair the short to ground on the circuit.
      • If infinite resistance - Replace the component: Q17 Fuel Injector
    • Go to next step: If infinite resistance 
  4. Ignition - On/Vehicle - In Service Mode
  5. Test for less than 1 V between the test points:
    • {Q17A Fuel Injector 1} Control circuit terminal 72 & Ground
    • {Q17B Fuel Injector 2} Control circuit terminal 71 & Ground
    • {Q17C Fuel Injector 3} Control circuit terminal 70 & Ground
    • If 1 V or greater 
    1. Disconnect the appropriate electrical connector: Q17 Fuel Injector
    2. Test for less than 1 V between the test points:
      • {Q17A Fuel Injector 1} Control circuit terminal 72 @ Control module harness & Ground
      • {Q17B Fuel Injector 2} Control circuit terminal 71 @ Control module harness & Ground
      • {Q17C Fuel Injector 3} Control circuit terminal 70 @ Control module harness & Ground
      • If 1 V or greater - Repair the short to voltage on the circuit.
      • If less than 1 V - Repair the short to voltage on the circuit:
    • Go to next step: If less than 1 V 
  6. Ignition/Vehicle - Off
  7. Test for less than 3 ohms between the test points:
    • {Q17A Fuel Injector 1} Control circuit terminal 72 & Control circuit terminal 52
    • {Q17B Fuel Injector 2} Control circuit terminal 71 & Control circuit terminal 51
    • {Q17C Fuel Injector 3} Control circuit terminal 70 & Control circuit terminal 50
    • If 3 ohms or greater 
    1. Disconnect the appropriate electrical connector: Q17 Fuel Injector
    2. Test for less than 2 ohms between the test points:
      • {Q17A Fuel Injector 1} Control circuit terminal 72 @ Control module harness & Control circuit terminal 2 @ Component harness
      • {Q17B Fuel Injector 2} Control circuit terminal 71 @ Control module harness & Control circuit terminal 2 @ Component harness
      • {Q17C Fuel Injector 3} Control circuit terminal 70 @ Control module harness & Control circuit terminal 2 @ Component harness
      • If 2 ohms or greater - Repair the open/high resistance in the circuit.
      • Go to next step: If less than 2 ohms
    3. Test for less than 2 ohms between the test points:
      • {Q17A Fuel Injector 1} Control circuit terminal 52 @ Control module harness & Control circuit terminal 1 @ Component harness
      • {Q17B Fuel Injector 2} Control circuit terminal 51 @ Control module harness & Control circuit terminal 1 @ Component harness
      • {Q17C Fuel Injector 3} Control circuit terminal 50 @ Control module harness & Control circuit terminal 1 @ Component harness
      • If 2 ohms or greater - Repair the open/high resistance in the circuit.
      • If less than 2 ohms - Replace the component: Q17 Fuel Injector
    • Go to next step: If less than 3 ohms 
  8. Disconnect the appropriate electrical connector: Q17 Fuel Injector
  9. Test for infinite resistance between the test points:
    • {Q17A Fuel Injector 1} Control circuit terminal 52 @ Control module harness & Control circuit terminal 72 @ Control module harness
    • {Q17B Fuel Injector 2} Control circuit terminal 51 @ Control module harness & Control circuit terminal 71 @ Control module harness
    • {Q17C Fuel Injector 3} Control circuit terminal 50 @ Control module harness & Control circuit terminal 70 @ Control module harness
    • If less than infinite resistance 

      Repair the short between the circuits.

    • Go to next step: If infinite resistance 
  10. Replace the component: K20 Engine Control Module
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