Diagnostic Aids
WARNING: This page is about a different car, the 2017 GMC Yukon XL, 2017 GMC Yukon, 2017 Chevrolet Tahoe, 2017 Chevrolet Suburban 3500 HD, and 2017 Chevrolet Suburban. However, it is still accessible from the selected car via links, so may be relevant.
If the electrical circuit tests are OK and the shift pattern is not occurring, there may be a mechanical/hydraulic condition that prevents operation. Refer to Symptoms - Automatic Transmission .