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Home >> GMC >> 2003 >> Safari Van Cargo, AWD >> Repair and Diagnosis >> Accessories & Equipment >> Communication Devices >> Data Link Communications System >> Diagnostic Information and Procedures >> DTC U1000 and U1255: Critical Operating Parameter Has Not Been Associated >> Diagnostic Aids

Diagnostic Aids

When a malfunction occurs while modules are communicating, a lost communication DTC is set as a current DTC. When the modules stop communicating the current lost communication DTC is cleared but the history DTC remains. When the modules begin to communicate again, the module with the open fuse will not be learned by the other modules so U1000 or U1255 is set current by the other modules. If the malfunction occurs when the modules are not communicating, only U1000 or U1255 is set.