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Home >> Chevrolet >> 2023 >> Tahoe SSV >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 7 (Engine Controls And Fuel - 3.0L (Lm2) Diesel - Diagnostic Information And Procedures (3 Of 5)) >> Diagnostic Information and Procedures >> DTC P0628, P0629, or P12A6 >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different variant/trim than selected.
  1. Ignition/Vehicle & All vehicle systems - Off
  2. Disconnect the electrical connector: K111 Fuel Pump Power Control Module
  3. Ignition - On/Vehicle - In Service Mode
  4. Perform the scan tool control function: Fuel Pump Control Circuit Low Test Status - Off

    Verify a test lamp does not turn On between the test points: Control circuit terminal 18 & Ground

    • If the test lamp turns On 
    1. Ignition/Vehicle - Off & Remove - Test lamp
    2. Disconnect the appropriate electrical connector: 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 18@Component harness & Ground
      • If 1 V or greater - Repair the short to voltage on the circuit.
      • If less than 1 V - Replace the component: K20 Engine Control Module
    • Go to next step: If the test lamp does not turn On 
  5. Remove - Test Lamp
  6. Perform the scan tool control function: Fuel Pump - On

    Verify the scan tool parameter: Fuel Pump Control Circuit Low Test Status = OK

    • If not the specified state 
    1. Ignition/Vehicle - Off
    2. Disconnect the appropriate electrical connector: K20 Engine Control Module
    3. Test for infinite resistance between the test points: Control circuit terminal 18@Component harness & Ground
      • If less than infinite resistance - Repair the short to ground on the circuit.
      • If infinite resistance - Replace the component: K20 Engine Control Module
    • Go to next step: If the specified state 
  7. Connect a 3 A fused jumper wire between the test points: Control circuit terminal 18 & Ground
  8. Perform the scan tool control function: Fuel Pump - On

    Verify the scan tool parameter: Fuel Pump Control Circuit Low Test Status = Malfunction

    • If not the specified state 
    1. Ignition/Vehicle - Off & Remove - Jumper wire(s)
    2. Disconnect the appropriate electrical connector: K20 Engine Control Module
    3. Test for less than 2 ohms between the test points: Control circuit terminal 18@Component harness & The other end of the circuit@Control module harness
      • If 2 ohms or greater - Repair the open/high resistance in the circuit.
      • If less than 2 ohms - Replace the component: K20 Engine Control Module
    • Go to next step: If the specified state 
  9. Test or replace the component: K111 Fuel Pump Power Control Module
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