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Hello. Welcome to JUst Answer. Please allow me to assist you. We need to do some diagnosis here; as taillights being out (with good fuses) can have 4 or 5 different common problems. If you have access to a 12 volt DC test light, or, a DC voltmeter, our diagnosis will be much more efficient.
Please advise if the front marker lights are operational, and, does this vehicle have a trailer towing wire installed . Then we can begin our tests.
Ok. We are going to need to remove the driver side tail lamp unit from the bed. Once you have that out, advise if there is a small black box inside where the tail lamp fits into the bedside.
then follow the trailer wire harness up under the bed until; you come to wire connector where the trailer wire plugs into, or, the aforementioned small box.
We need to locate the solid GREEN wire in the driver side rear. Check for power in the main tailight wire connection from under the bed.
The solid GREEN wire is power for the taillamps and the license plate lamps. It is not uncommon for the trailer interface box to fail or short out.. This would allow no tail lamps as you are experiencing.
ok. The box could be anywhere under the bed, or in the other taillamp area.
And there is no power in the green wire under the bed. Is the power in the green wire under the hood?
Is there power in both sides of the TAIL fuse with the switch turned on. Please advise.
The non-powered side of the taillamp fuse is connected to the Green wire that feeds power to the taillamps and the license plate lamps. There is a splice in the wire harness under the bed. Follow the main under-bed wire harness on the driver side to the taillamps. Pierce probe for power in the green wire. I am thinking that the splice connection is corroded. If you find power anyplace in the green wire under the bed, splice a separate wire into where you have power and then run it back to the driver side taillamp wire connector. Splice back into the no-power green wire and your lights should start to work again. Corrosion on the taillamp wire splice is very common, finding the splice is rather difficult. Actually, there are 3 splices. One splice connects the driver side power (from the fuse) to the driver side taillamp, another supplies power to the left license plate lamp, and, the final splice supplies power to the right taillamp and the right license plate lamp.
All of these splices are at the very end of the under-bed part of the harness, where the wire from the taillamp connection comes down to meet the main harness.
Oh. I'm sorry. Did not know. OK. I will be back online tomorrow after 6:30 PM east coast time.