Here is a bulletin, be aware of the models affected, particulrily the build date. It can be found on the door sticker.
#PIT4126: Check Engine Light On P0411 or P0418 or Air Pump Fuse Blown - keywords 3.7L CEL code harness lamp light LLR short - (Sep 20, 2006)
Subject: Check Engine Light On P0411 Or P0418 Or Air Pump Fuse Blown
Models: 2007 Hummer H3 built before August 11, 2006
The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.
Condition/Concern: The check engine light is on with a P0411 or P0418 and/or the air pump fuse blown. This can be caused by a short in the pink wire circuit 439 from air pump relay located on left side of block, rubbing against master cylinder/ABS module blowing the 10 amp air pump relay fuse.
Recommendation/Instructions: Repair the wires as needed, then use a tie strap to reposition the harness to prevent the harness from chaffing.
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.