Tail light fuse keeps blowing. I have traced the wiring back to the tail lights and it all seems fine. I have taken out the turn signal lights and the light switch, put in to the first position for parking lights, still blows the fuse. I have also disconnected the Side marker lights and the fuse will still blow. Any suggestions as what to do / where to look for the short or frayed wires?

You have a shorted wire, get a wiring diagram and trace down the wiring to find the short

Ben, it could be something as simple as a bad tail light bulb or socket shorting out. Check all tail light bulbs, sockets and wiring for damage burnt etc.
Does it blow immediately, or when you turn lights on, or when you use left or right signal, or when brake is applied? this can help trace problem.

The ground wiring on newer vehicles is a little complicated. Older cars, the ground would have been to the body around the tail-lights, but these have a ground wire in the harness and is connected to the turn-signal switch, and other sources. I don't think you have a ground problem. Does the fuse blow as soon as you press it into the fuse-block, or when you step on the brake? I believe you have a dead short somewhere, possibly a pinched turn-signal wire close to the tail-light assembly. Brake lights work through the turn-signal wires from the turn-signal switch on the steering column. That's how you can have one side blinking for turn while the other side stays on for brake. I'm kind of shooting in the dark here because I don't know what all you've done. If you replaced the turn-signal switch in the steering column, you may have pinched a wire or something there. Another thing, if the fuse doesn't blow as soon as you press it in, will both turn-signals work as long as you don't press on the brake? If you can provide a little more information, I might be able to help you more. One last thing....Have you replaced tail-light/turn-signal bulbs? If so, be sure you used the right bulb. You should only have two bulbs, one for back-up lights and one 1157-type combination for tail-lights and turn-signals. I have seen people use a single contact (1056) bulb in place of a 1157, which creates a short from brake/turn-signal back into the tail-light circuit. I do have a 1994 Dodge Dakota.

If the fuse blows, you have a dead short to ground somewhere, likely around the tail lights or parking lights. Try this:

Get a box of the correct fuses.
Remove all tail and parking bulbs and put in a new fuse. If the fuse does not blow, try installing each bulb at a time to see which light assembly causes the fuse to blow.
Let's suppose its the RH tail light assembly. Pull it off the car and check for dirt and damaged wiring.

If this is an older vehicle, there may be wiring damage (due to rust) in the harness under the carpets.

You have a serious short circuit in the wiring to the tail lights. Fuses protect the wiring in your vehicle from catching fire.
You need to trace the tail light wiring from the fuse box to the tail lights to locate the fault/short circuit.
A wiring diagram can help as it shows the colour code of the wires to the tail lights.
This problem can be difficult to trace and you most likely need an auto electrician to fix this problem. It could mean installing a new wire to the tail lights as a quicker fix and bypass the fault..

I strongly suggest your first priority will be to discover why your tail lights are seemingly consuming many times more current than they should. A 30 amp fuse has less resistance than a 10 amp though the difference is hardly measurable.

I suspect when that is sorted out the other faults could disappear without further effort.

It is time to find a circuit diagram and to trace the tail light wiring from the supply to the lamps in order to discover what went wrong.

because you have 2 wires touching somewhere in that circuit, you'll have to trace the wiring to find it. Usually start at the back at the tail lights

if its blowing fuses, you have a short(power being touched to ground) Electrical can be hard to trace. Find you a wiring schematic for you vehical and trace each wire, look for loose connections and possible wires melted to each other. Hope this is a help.

it's one of your fuses that burned out. buy a fuse tester at any auto parts and test all your fuses. when lights and horns fail as a group, it's usualy the fuse that protects these multiple parts that's gone bad.