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Home >> Chevrolet >> 2010 >> Traverse LT, AWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 472 (HVAC System - Automatic) >> Diagnostic Information and Procedures >> DTC P0645, P0646, or P0647: Air Conditioning (A/C) Compressor Clutch Relay >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different car, the 2016 GMC Acadia, 2016 Chevrolet Traverse, and 2016 Buick Enclave. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ignition OFF, disconnect the KR29 A/C compressor clutch relay, ignition ON.
  2. Verify a test lamp illuminates between the B+ circuit terminal 30 and ground.
    • If the test lamp does not illuminate and the circuit fuse is good 
    1. Ignition OFF.
    2. Test for less than 2 Ω in the B+ circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, verify the fuse is not open and there is voltage at the fuse.
    • If the test lamp does not illuminate and the circuit fuse is open 
    1. Ignition OFF.
    2. Test for infinite resistance between the B+ circuit and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • If infinite resistance,
    3. Disconnect the harness connector at the Q2 A/C compressor clutch.
    4. Test for infinite resistance between the control circuit terminal 87 and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • If infinite resistance, test or replace the Q2 A/C compressor clutch.
    • If the test lamp illuminates 
  3. Ignition ON.
  4. Verify a test lamp illuminates between the ignition circuit terminal 85 and ground.
    • If the test lamp does not illuminate 

      Replace the X50A underhood fuse block.

    • If the test lamp illuminates 
  5. Connect a test lamp between the ignition circuit terminal 85 and the control circuit terminal 86.
  6. Verify the test lamp turns ON and OFF when commanding the Engine Control Module A/C Compressor Clutch Relay ON and OFF with a scan tool.
    • If the test lamp is always OFF 
    1. Ignition OFF, disconnect the harness connector at the K20 engine control module, ignition ON.
    2. Test for less than 1 V between the control circuit and ground.
      • If 1 V or greater, repair the short to voltage on the circuit.
      • If less than 1 V
    3. Ignition OFF.
    4. Test for less than 2 Ω in the control 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 the test lamp is always ON 
    1. Ignition OFF, disconnect the harness connector at the K20 engine control module,
    2. Test for infinite resistance between the control circuit and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • If infinite resistance, replace the K20 engine control module.
    • If the test lamp turns ON and OFF 
  7. Verify a test lamp does not illuminate between the control circuit terminal 87 and ground.
    • If the test lamp illuminates 

      Repair the short to voltage on the circuit.

    • If the test lamp does not illuminate 
  8. Ignition OFF and all vehicle systems OFF, disconnect the harness connector at the Q2 A/C compressor clutch. It may take up to 2 minutes for all vehicle systems to power down.
  9. Test for less than 10 Ω between the ground circuit terminal 1 and ground.
    • If 10 Ω or greater 
    1. Ignition OFF.
    2. Test for less than 2 Ω in the ground circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, repair the open/high resistance in the ground connection.
    • If less than 10 Ω 
  10. Connect the harness connector at the Q2 A/C compressor clutch.
  11. Ignition ON, connect a 10 A fused jumper wire between the B+ circuit terminal 30 and the control circuit terminal 87.
  12. Verify the Q2 A/C compressor clutch is activated.
    • If the Q2 A/C compressor clutch does not activate 
    1. Ignition OFF, disconnect the harness connector at the Q2 A/C compressor clutch.
    2. Test for less than 2 Ω in the control circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, test or replace the Q2 A/C compressor clutch.
    • If the Q2 A/C compressor clutch activates 
  13. Test or replace the KR29 A/C compressor clutch relay.
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