Diagnostic Aids

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

When a malfunction such as an open fuse to a module occurs while modules are communicating, a Loss of XXX Communication DTC is set as current. When the modules stop communicating, the ignition is turned OFF, the current Loss of XXX Communication DTC is cleared but the history DTC remains. When the modules begin to communicate again, the ignition is turned ON, the module with the open fuse will not be learned by the other modules so U1000 is set current by the other modules. If the malfunction occurs when the modules are not communicating, only U1000 is set. When this DTC sets, the module uses a default value for the missing parameter. A current DTC U1000 will clear when all of the critical operating parameters for the module have been associated with an identification number or when the current ignition cycle end. A history U1000 will clear upon executing 100 ignition RUN cycles with no recurrence of the malfunction.