1989 GMC Sierra Tail lights

1989 GMC SIERRA
16,000 MILES • V8 • FWD • AUTOMATIC
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MYGMC89
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I have an 89' GMC half ton. The brake lights and turn signals work fine when my headlights are off. When I turn on my headlights the passanger tail light brake light doesn't work, but only when my headlights are on. Also it is very dim. Ihave changed fuses and light bulbs but the problem is still there. What can I do?
Nov 17, 2009 at 3:20 PM
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JDL
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Welcome to the forum, your lower brake lites and turn signal use the same bulb filament just not at the same time. I'd have to check voltage and ground at the rear. Brown wire is voltage for tail lights, yellow is voltage for brake/turn, black is ground.
Nov 17, 2009 at 3:42 PM
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