Diagnostic Aids

WARNING: This page is about a different car, the 2002 GMC Sierra, 2002 GMC Cab & Chassis Sierra, 2002 Chevrolet Silverado, and 2002 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.

The diagnosis of U1305 is accomplished via the symptom. Refer to Scan Tool Does Not Communicate with Class 2 Device .
An intermittent condition is likely to be caused by a short to ground, or voltage on the Class 2 serial data circuit. Refer to Scan Tool Does Not Communicate with Class 2 Device .