So I have my LS swap running, but I have a problem with the turn signal/back up light fuse. It works in key on position, but as soon as I turn the truck over to crank position to start it it blows the fuse. I have heard it can be multi-function switch ,but I would think it wouldn't work in key on position? I have looked for any shorts, but I have had no luck finding one under the dash or wiring up by the headlights.

HELP!!!!!!