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.
Inspect the ISS/OSS, harness, connector, and control solenoid valve assembly for metallic debris and the 1-2-3-4 and 3-5-R clutch housing splines on the outside diameter surface for damage or misalignment. Proper torque of the ISS/OSS mounting bolt is critical to proper speed signal operation.