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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 U1001 To U1254: Module U1XXX Communication >> Test Description

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. 1.  A module which loses power during an ignition cycle will cause other module to set lost communication DTCs.
  2. 2.  A module which loses power during an ignition cycle will cause other module to set lost communication DTCs.
  3. 3.  The malfunction is due to an open in the class 2 serial data circuit or an open in the module.
  4. 7.  The module which was not communicating due to an open in the class 2 serial data circuit may have set lost communication DTCs for those modules that it was monitoring.
  5. 9.  The modules which can communicate indicate the module which cannot communicate. You must clear the DTCs from these modules to avoid future misdiagnosis.