Code p0705, downshifts when blinker engages

This is so no one else hopefully has to deal with this. Engine light came on, eingine downshifted when engaging blinkers, blinkers and brakes malfunctioning, code p0705.
I spent hours trying to fix the neutral safety switch, the automatic transition range sensor circuit, took it to the dealer, they checked some crap out. Last thing I checked was the rear lights, all of them.
Listen carefully, so eventually it started blowing the 10a fuse under the dash and I couldn't even get the vehicle in gear. Narrowed down to the braking system so I took tail light fixtures offline one at a time. It ended up being the right running/brake light bulb but ONLY when I turned it into the housing. So I just left it flopping around in there. Luckily bulb too big to fit back through the hole.
I need to spend more money on purchasing those rear fixtures next time.

Thanks for listening

 

Thank you for posting this. What year is your truck?

 

2003 double cab sorry for my delay but I'm back in the forum because of similar issue that I'd forgotten about. I'm getting old.