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Home >> Chevrolet >> 2020 >> Malibu LS >> Repair and Diagnosis >> External Pages >> Different car >> Section 17 (Engine Cooling System) >> Diagnostic Information and Procedures >> DTC P2600-P2603 >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different car, the 2019 Chevrolet Malibu. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ignition/Vehicle - Off
  2. Disconnect the electrical connector:G36 Auxiliary Heater Coolant Pump
  3. Test for less than 10 ohms between the test points:Ground circuit terminal 1 & Ground
    • If 10 ohms or greater 
    1. Disconnect the ground connection:Terminal G120
    2. Test for less than 2 ohms between the test points:Ground circuit terminal 1 & Terminal G120
      • If 2 ohms or greater - Repair the open/high resistance in the circuit.
      • If less than 2 ohms - Repair the open/high resistance in the ground connection.
    • Go to next step: If less than 10 ohms 
  4. Verify the fuse is not open:F99UA Fuse
    • If the fuse is open 
    1. Replace the component:F99UA Fuse
    2. Verify the fuse does not open.
      • If the fuse opens - Test or replace the component:X50A Fuse Block - Underhood
      • Go to next step: If the fuse does not open, go to the next step.
    • Go to next step: If the fuse is not open 
  5. Ignition - On / Vehicle - In Service Mode
  6. Connect a test lamp between the test points:Control circuit terminal 2 & Ground circuit terminal 1
  7. Perform the scan tool control function:Heater Coolant Pump - On and Off

    Verify the test lamp does not turn On and Off.

    • If the test lamp turns On and Off 

      Test or replace the component:G36 Auxiliary Heater Coolant Pump

    • Go to next step: If the test lamp does not turn On and Off 
  8. Ignition/Vehicle - Off
  9. Connect the electrical connector:G36 Auxiliary Heater Coolant Pump
  10. Disconnect the electrical connector:X4 - X50A Fuse Block - Underhood
  11. Ignition - On / Vehicle - In Service Mode
  12. Momentarily connect a 7.5 A fused jumper wire between the test points:Control circuit terminal X4 C1 & B+

    Verify the component turns On and Off when connecting and disconnecting the jumper wire:G36 Auxiliary Heater Coolant Pump

    • If the component does not turn On and Off 
    1. Ignition/Vehicle - Off & Remove - Jumper wire (s)
    2. Disconnect the electrical connector:G36 Auxiliary Heater Coolant Pump
    3. Test for infinite resistance between the test points: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
    4. Test for less than 2 ohms between the test points:Control circuit terminal 2 @ Component harness & Control circuit terminal X4 C1 @ Fuse Block Harness
      • If 2 ohms or greater - Repair the open/high resistance in the circuit.
      • If less than 2 ohms - Test or replace the component:G36 Auxiliary Heater Coolant Pump
    • Go to next step: If the component turns On and Off 
  13. Ignition/Vehicle - Off
  14. Connect the electrical connector:X4 - X50A Fuse Block - Underhood
  15. Disconnect the electrical connector:X1 - K20 Engine Control Module
  16. Connect a 10 A fused jumper wire between the test points:Control circuit terminal X1 67 @ Control module harness & Ground
  17. Ignition - On / Vehicle - In Service Mode
  18. Momentarily connect a 10 A fused jumper wire between the test points:Control circuit terminal X1 66 @ Control module harness & Ground

    Verify the component turns On and Off when connecting and disconnecting the jumper wire:G36 Auxiliary Heater Coolant Pump

    • If the component does not turn On and Off 
    1. Ignition/Vehicle - Off & Remove - Jumper wire (s)
    2. Test for infinite resistance between the test points:Control circuit terminal X1 66 @ 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. Disconnect the electrical connector:X4 - X50A Fuse Block - Underhood
    4. Test for less than 2 ohms between the test points:Control circuit terminal X1 66 @ Control module harness & Terminal X4 B3 @ Fuse Block Harness
      • If 2 ohms or greater - Repair the open/high resistance in the circuit.
      • If less than 2 ohms - Test or replace the component:X50A Fuse Block - Underhood
    • Go to next step: If the component turns On and Off 
  19. Replace the component:K20 Engine Control Module
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