Diagnostic Aids

WARNING: This page is about a different car, the 2000 Chevrolet Corvette. However, it is still accessible from the selected car via links, so may be relevant.

The following conditions may cause a "U" code to set:

Intermittent open or short in serial data line.
Intermittent open between the inoperative module and a star connector.
Poor connection at inoperative module or star connector.
Intermittent open in star connector.
Improperly powered module or system.