Circuit/System Testing
WARNING: This page is about a different car, the 2017 GMC Yukon XL, 2017 GMC Yukon, 2017 Chevrolet Tahoe, and 2017 Chevrolet Suburban. However, it is still accessible from the selected car via links, so may be relevant.
- Monitor the scan tool parameter:4WD Low Signal - (K20)
- Operate the component:S77 Transfer Case Shift Control Switch - 4WD Low
- Verify the scan tool parameter:4WD Low Signal=Enabled
- If the parameter does not display the following:
Enabled
Test or replace the component: Transfer Case Assembly
- If the parameter displays the following:Enabled
- If the parameter does not display the following:
Enabled
- Operate the component:S77 Transfer Case Shift Control Switch - 2WD
- Verify the scan tool parameter:4WD Low SignalDisabled
- If the parameter does not display the following:Disabled
Test or replace the component:Transfer Case Assembly
- If the parameter displays the following: =Disabled
- If the parameter does not display the following:Disabled
- Program the ECM.
- Operate the component:S77 Transfer Case Shift Control Switch - 4WD High/Locked
- Operate the vehicle within the Conditions for Running the DTC.
- Verify the DTC does not set.
- If the DTC sets
Replace the component:K20 Engine Control Module
- If the DTC does not set
- If the DTC sets
- Operate the component:S77 Transfer Case Shift Control Switch - 4WD Low
- Operate the vehicle within the Conditions for Running the DTC.
- Verify the DTC does not set.
- If the DTC sets
Replace the component:K20 Engine Control Module
- If the DTC does not set
- If the DTC sets
- Operate the component:S77 Transfer Case Shift Control Switch - Neutral
- Operate the vehicle within the Conditions for Running the DTC.
- Verify the DTC does not set.
- If the DTC sets
Replace the component:K20 Engine Control Module
- If the DTC does not set
- If the DTC sets
- All OK.