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Home >> GMC >> 2018 >> Terrain SL >> Repair and Diagnosis (Single Page) >> Accessories & Equipment >> Memory Modules >> Secondary And Configurable Customer Control System >> Diagnostic Information And Procedures >> Drive Mode Switch Malfunction (Chevrolet With AWD) >> Circuit/System Testing

Circuit/System Testing

  1. Ignition/Vehicle & All vehicle systems - Off
    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.
  2. Disconnect the electrical connector: S126 Drive Mode Select Switch
  3. Test for less than 10 Ω between the test points: Ground circuit terminal 8 & Ground
    • If 10 Ω or greater 
    1. Test for less than 2 Ω between the test points: Ground circuit terminal@Component harness & Ground terminal
      • 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.
    • Go to next step: If less than 10 Ω 
  4. Ignition - On / Vehicle - In Service Mode
  5. Test for 4.8 to 5.2 V between the test points: 5 V Reference circuit terminal 3 & Ground
    • If less than 4.8 V 
    1. Ignition/Vehicle - Off
    2. Disconnect the electrical connector:K20 Engine Control Module
    3. Test for infinite resistance between the test points: 5 V Reference circuit terminal @ Component harness & Ground
      • If less than infinite resistance - Repair the short to ground on the circuit.
      • If infinite resistance
    4. Test for less than 2 Ω between the test points: 5 V Reference circuit terminal @ Component harness & The other end of the circuit @ Control module harness
      • If 2 Ω or greater - Repair the open/high resistance in the circuit.
      • If less than 2 Ω - Replace the component:K20 Engine Control Module
    • If greater than 5.2 V 
    1. Ignition/Vehicle - Off
    2. Disconnect the electrical connector: K20 Engine Control Module
    3. Ignition - On / Vehicle - In Service Mode
    4. Test for less than 1 V between the test points: 5 V Reference circuit terminal @ 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 between 4.8 and 5.2 V 
  6. Test for less than 1 V between the test points:Signal circuit terminal 4 & Ground
    • If 1 V or greater 
    1. Ignition/Vehicle - Off
    2. Disconnect the electrical connector:K20 Engine Control Module
    3. Ignition - On / Vehicle - In Service Mode
    4. Test for less than 1 V between the test points:Signal circuit terminal@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 less than 1 V 
  7. Ignition/Vehicle & All vehicle systems - Off
  8. Disconnect the electrical connector: K20 Engine Control Module
  9. Test for infinite resistance between the test points:Signal 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 
  10. Test for less than 2 Ω between the test points: Signal circuit terminal 4 @ Component harness & The other end of the circuit @ Control module harness
    • If less than infinite resistance 

      Repair the open/high resistance in the circuit.

    • Go to next step: If infinite resistance 
  11. Test or replace the component: S126 Drive Mode Select Switch
  12. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

    Verify the DTC does not set.

    • If the DTC sets 

      Replace the component:K20 Engine Control Module

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