Diagnostic Aids

WARNING: This page is about a different car, the 2003 Pontiac Grand Prix. However, it is still accessible from the selected car via links, so may be relevant.

This DTC cannot be retrieved with a current status. The diagnosis of U1304 is accomplished via the symptom, Scan Tool Does Not Communicate with UART Data Line. Refer to SCAN TOOL DOES NOT COMMUNICATE WITH UART DATA LINE .
An intermittent condition is likely to be caused by a short to ground or voltage on the UART data line circuit. Use the Scan Tool Does Not Communicate with UART Data Line procedure in order to isolate an intermittent condition. Refer to SCAN TOOL DOES NOT COMMUNICATE WITH UART DATA LINE .