HiCustomer GM says that there is an issue with a bad steering column ground on these. Rather than make up a ground you could use a jumper wire to ground the column and if that makes it work, then follow the GM instructions below. If not and you still need to get to the horn switch just let me know. Thanks
Subject:Horn Inoperative At Times - keywords bracket column condition contact electrical ground horn wire #PIT3300G - (02/01/2007)
Models:2004-2005 Buick Rainier 2002 Cadillac Escalade and Escalade EXT1999-2002 Chevrolet Silverado, Avalanche, Tahoe and Suburban2002-2007 Chevrolet Trailblazer and Trailblazer Ext2002-2007 GMC Envoy Envoy XUV and Envoy XL1999-2002 GMC Sierra, Yukon and Yukon Denali2002-2004 Oldsmobile Bravada2005-2007 Saab 97x
This PI was superseded to update Models.Please discard PIT3300F.
The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.
Application of horn at horn pad inoperative at times. RKE function for panic alarm works.
Refer to item number 2 in the line art below. This line art shows the column support assembly. A closer look will reveal the 4 mounting holes of the column support assembly. Add (one) grounding strap from the column mount (use only one of the two upper mounting holes) to one of the two lower mounting holes in the steering column support assembly. If a grounding strap cannot be obtained locally, one can be made obtaining two eyelets that match the size of the column support bolts or studs and a 12 gauge (3.0mm) wire. Cut the wire to the length needed in order to complete the circuit.
Note: Some model year vehicles switched to column bracket and/or mount that may be isolated by rubber. It may be necessary to locate an alternate location to secure the ground wire to the column or column bracket in order to compete the circuit.
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.
GM bulletins are intended for use by professional technicians, NOT a "do-it-yourselfer". They are written to inform these technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions, and know-how to do a job properly and safely. If a condition is described, DO NOT assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See your GM dealer for information on whether your vehicle may benefit from the information. WE SUPPORT VOLUNTARY TECHNICIAN CERTIFICATION
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Document ID#(NNN) NNN-NNNN2000 Chevrolet Chevy K Silverado - 4WD