Expert Answers about GMC W-Series

• Where to Find Brake Light Only Circuit on a 2008 GMC W4500
• Does your 2008 GMC W4500 have a third brake light (or at least the circuit for a third brake light)? That would be a better option than the regular brake lights. You can check the fuse panel for the CHMSL (center high mount stop light) fuse, if applicable, and tap into it. The issue with using another circuit though is that if anything else is on that same circuit then the brake controller could send voltage back to the trailer brakes when you don't want it to. Another possible option...
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