U1003

Subject: Communication Faults DTCs U1003 U1004 U1006 U1007 U1009 - keywords 4WD ABS brake IPC TCCM PIT3793 - (12/07/2005)

Models: 2003-2006 Chevrolet Silverado 2003-2006, GMC Sierra 2500 and 3500 Series

The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

Condition/Concern:
During normal diagnostics, any one of the following communication DTCs may be found U1003, U1004, U1005, U1006, U1007 and/or U1009. When searching in SI for a diagnostic flow chart, none will be found. Any one of these DTCs can be falsely set by a "garbled" class 2 message.

Recommendation/Instructions:
These DTCs should be cleared and ignored. A "garbled" class 2 message could be caused by a poor ground. Several cases for repairing G100, G104, G107, G110 having been reported.

Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.