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Circuit/System Testing

WARNING: This page is about a different car, the 2021 GMC Sierra 3500 HD and 2021 GMC Sierra 2500 HD. However, it is still accessible from the selected car via links, so may be relevant.
NOTE:

It may take up to 2 min for all vehicle systems to power down before an accurate ground or low reference circuit continuity test can be performed.

  1. Ignition/Vehicle & All vehicle systems - Off
  2. Disconnect the electrical connector: K77 Remote Control Door Lock Receiver
  3. Test for less than 10 ohms between the test points: Low Reference circuit terminal 1 @ Component harness & Ground
    • If 10 ohms or greater 
    1. Disconnect the electrical connector: K9 Body Control Module
    2. Test for less than 2 ohms between the test points: Low Reference circuit terminal 1 @ Component harness & Terminal 16 X2 @ Control module harness
      • If 2 ohms or greater - Repair the open/high resistance in the circuit.
      • If less than 2 ohms - Replace the component: K9 Body Control Module
    • Go to next step: If less than 10 ohms 
  4. Test for 11.8 to 12.5 V between the test points: B+ circuit terminal 4 & Ground
    • If less than 11.8 V 
    1. Ignition/Vehicle - Off
    2. Disconnect the electrical connector: K9 Body Control Module
    3. Test for infinite resistance between the test points: B+ circuit terminal 4 @ 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: B+ circuit terminal 4 @ Component harness & Terminal 25 X2 @ Control module harness
      • If 2 ohms or greater - Repair the open/high resistance in the circuit.
      • If less than 2 ohms - Replace the component: K9 Body Control Module
    • Go to next step: If between 11.8 and 12.5 V 
  5. Ignition - On / Vehicle - In Service Mode
  6. Test for 3 to 6 V between the test points: Serial Data circuit terminal 3 & Ground
    • If less than 3 V 
    1. Ignition/Vehicle - Off
    2. Disconnect the electrical connector: K9 Body Control Module
    3. Test for infinite resistance between the test points: Serial Data circuit terminal 3 @ 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: Serial Data circuit terminal 3 @ Component harness & Terminal 26 X1 @ Control module harness
      • If 2 ohms or greater - Repair the open/high resistance in the circuit.
      • If less than 2 ohms - Replace the component: K9 Body Control Module
    • If greater than 6 V 
    1. Ignition/Vehicle - Off
    2. Disconnect the electrical connector: K9 Body Control Module
    3. Ignition - On / Vehicle - In Service Mode
    4. Test for less than 1 V between the test points: Serial Data circuit terminal 3 @ Component harness & Ground
      • If 1 V or greater - Repair the short to voltage on the circuit.
      • If less than 1 V - Replace the component: K9 Body Control Module
    • Go to next step: If between 3 and 6 V 
  7. Ignition/Vehicle - Off
  8. Disconnect the electrical connector: X1 & X2 @ K9 Body Control Module
  9. Ignition - On / Vehicle - In Service Mode
  10. Test for less than 1 V between the test points: Serial Data 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 
  11. Ignition/Vehicle - Off
  12. Test for infinite resistance between the test points: Serial Data 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 
  13. Test for less than 2 ohms between the test points: Serial Data circuit terminal 2 @ Component harness & Terminal 27 X2 @ 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 
  14. Replace the component: K77 Remote Control Door Lock Receiver
  15. Verify DTC B3101 is not set.
    • If DTC B3101 is set 

      Replace the component: K9 Body Control Module

    • Go to next step: If the DTC is not set 
  16. All OK.
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