No tail lights 2006 Buick terraza

Do the front park lamps work? If so, I think you have a wiring circuit problem going to the rear or at the rear. The front and rear park lamps use the same fuse, same relay. If none work, front or rear, then the fuse in diagram, hot all the time, use test light to check voltage at the fuse. You can see park lamp relay. You can see wire colors to tail lamps from relay, that is voltage. The bottom wire at tail lamps in diagram, black wire is ground. You need both voltage and ground. You can use a test light to check both. The headlamp switch signals the bcm that you turn on headlamp switch, then the bcm grounds the control side of park lamp relay.

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2005 buick terraza keeps blowing turns single fuse when you turn blinkers on left or right