Diagnostic Aids
WARNING: This page is about a different car, the 2018 GMC Yukon XL, 2018 GMC Yukon, 2018 Chevrolet Tahoe, 2018 Chevrolet Suburban 3500 HD, and 2018 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.