I've replaced headlight switch, turn signal switch and fuse box TIPM, 1600 dollars spent, im a mechanic, when I push the cargo light switch the headlights and marker lights come on and the interior dimmer works, but no blinkers or Hazzards my quess is a harness issue but I'm hoping someone else will have an idea, I've read all the other forums and there is a bunch of guessing going on, please don't post guesses here we need a answer im willing to pay for the answer, this vehicle was in a rear end collision I took the bed off repaired all damage truck worked fine when it left now I have this issue. Has a banks turbo with control computer, and a reverse camera, along with trailerbrake aftermarket install im at my wits end and I'm pretty good with diagnostics, I do it everyday??? Can anyone help

 

I just did lighting issue on my 2002 last week, so this is somewhat familiar to me.
Check the trailer lighting plug(s) to see if you are having the same fault.
They are independent, but parallel systems. This is in this way so if your trailer wiring is short circuited, they won't also kill your truck lighting when you plug in0.

My thoughts are that if the trailer lighting circuits ARE WORKING but the chassis lights are not, then that may reveal where and what to look for in the wiring.
IF THE trailer lighting circuits are doing the same thing as the chassis lighting circuits that it may indicate that the fault is in the control circuits or BCM.

Now, seeing that you have already wheeled out the parts cannon so now you MAY HAVE some variables that were introduced.

Please make it a point to return here and tell us what you find and how you fix it.
These forums are give AND take... so payment in the form of a solution is requested.

good luck, and thank you for your anticipated feedback
Cheers!