I have a short in my tail lights fuse f06
I've unplugged the rear lights nothing
Took the stereo out, unhooked gauge cluster I've tested the multi switch and checks out.
fuse won't blow untill I turn lights on to park or headlights on
When I test pin 5 on the 10 pin pigtail I get continuity to ground.. its the brown wire
pulling my hair out, does the brown wire go right into pcm? Or fuse block?
I dont understand wiring diagrams
Thanks
08 f150 fx4

 

Have you inspected/cleaned grounds?

 

https://www.f150forum.com/f4/ground-...iagram-494821/

 

Good luck

 

A typical "bad" ground will NOT cause fuses to blow - red herring. The OP has a "bad ground problem in which there is a short to ground where one is not supposed to be. That's why it's called a "short circuit" as the current is taking a shortcut to ground instead of going through the load to ground.

 

The trailer tow harness is electrically isolated from the main truck's lighting circuits by relays. A short in the trailer tow harness will NOT cause fuse F06 to blow. Another dead end.

 

Don't know what connector you're referring to...

The brown wire is the running (parking) lamp circuit. It comes from the headlight switch and goes to all the various loads that it's supposed to such as the front and rear running lights, license plate lights, trailer tow relay and is connected to the VSM (which can also activate the circuit). Something is shorted to ground. Could be a defective component or a wire fault such as one that is chafed or pinched.

 

I'm referring to the headlight switch pig tail..10 pin connector, pin 5 brown wire is ground? I'm sure it's supposed to be +??

 

Covered already, see previous.

 

I'd hook the multimeter to the brown wire that's grounded and go around moving the wiring harness in various places to see if you can locate the grounded spot.