earlier tognhtegt

 

sounds like a wire is grounding out

 

it was working fine makes me wish the sheet was taken off the truck any idea's on how i can fix the issue to have tail lights.

 

Sounds like a hot piece of metal from the cutting operation may have melted your tailight circuit wire to a ground. (dead short). A bad ground won't blow fuses, because with a bad ground there is a high resistance path that won't allow current to flow. A bad ground will cause other light circuits to dim as current (in this instance the tailight circuit) tries to find a path back to the battery.
The fix: Everything was working before you took your truck to the welding shop, but you have to determine if this problem is a result of the work on your truck or just a coincidence. Under the right seat you will find a plug which connects the cab harness to the rear body harness. Separate this plug and then try your fuse again, if it holds then you have isolated your problem to the rear.
You don't say what year your truck is, but if your avatar is a picture of your pickup then for a 4Runner of your vintage the tailight circuit is a solid green wire, I don't know if your pick-up is the same. Normally you can check continuity from the power wire (green) to the ground (white/black) in this plug. You set your multi-meter to give an audible beep and you carry on. You can't do that with light circuits, because the circuit will complete through any bulb element and you will always read a complete circuit from power to ground. You have to isolate the bulbs. Remove them all from their sockets or unplug the wires feeding them from the harness. Removing them from the sockets is a little more time consuming, but the best way to go. Once removed you will check for continuity at the plug under the seat, then unplug the individual circuits from the harness one at a time as you check for continuity. For example with the bulbs removed and you find a ground circuit when you check for continuity, unplug the licence plate lights, check again, unplug the right taillight assembly, check again, unplug the right side marker light (if any) check again. Keep doing this until all of the rear plugs are separated from the harness and the final check will be the harness from under the seat to the rear plugs. If you lose the ground circuit after a particular plug is seperated then your problem is in the wiring or the bulb receptacles of that accessory. For example if you had a ground circuit before, but not after you unplugged the right tail light assembly then your problem is the right tailight assembly.
If you do find that your problem is in the harness that goes to the back of the truck (which I suspect it is), then your only option is to remove the tape from the harness and visually inspect the wiring. A dead short will be pretty obvious. Then the fix is to splice the wires. Solder and heat shrink with a sealant in it is the only fix for automotive wiring. Using a butt splice (compression connector) is a lazy fix and will cause you problems because of moisture and corrosion not too far down the road.
Good Luck.

 

thanx for the help. i have a 88 DLX 22re same one in my sig . i switched to trailer lights about 5 mins ago (same thing) but im checking out the rest of the wiring right now

 

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my tail light fuse pops every single time i go out wheeling so i think it could be shorting against the frame or something

 

what color wire is for the tail lights in the rear? or what other wire's can i splice into to run another set of tail lights?

really don't want to run more wire cause then i'd need a relay (30amp i think) a switch and 2 more lights (2.99 at tractor supply)

 

My 86 wiring diagram manual shows the taillight circuit as being a green wire for both a pickup and a 4Runner. I already mentioned that my 89 4Runner was green as well, so it's a pretty safe bet that your 88 also has a green wire for the taillight circuit. If you have access to a multimeter and do the checks that I listed in my previous post, you can isolate your problem. Fixing it will also give you a change to inspect your harness from under the passengers seat to the rear of your truck. Your tailights are not working, but what other damage could there be that might cause other circuits to fail later on. Everytime a wire shorts to ground if it's not a dead short, but a partial short to ground, you have a chance of heat and ultimately a fire, plus I don't think that I'd want anything shorting so close to my gas tank!

 

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Toyota puts relays in heavily loaded circuits for a reason! You got your lights working and it looks like it's only two extra bulbs, but is the circuit that runs your CD player designed for that extra load?