Guys look at my post above. Mine was good for a while and came back again. It was in the lower connector on the frame behind the plastic shield right under the driver door. Cruise would shut off when using the blinker. Blinkers fast when brake was applied and normal speed with no brake applied.
I ended up putting more strands of copper to make the connection even tighter. See how long it lasts this time.

 

wfburon159 I had contacted you a year ago when my truck did this the 1st time. the next morning it was fine and I couldn't reproduce it. well as luck would have it...about a year later it did it again. this time I can't figure it out. this is what it does:

1. on the brake the blinkers flash really fast
2. with the headlamps on the blinkers flash really fast
3. headlamps on and foot the brake the blinkers flash very little
4. in reverse and on the brake the blinkers will not flash at all
5. sometimes sitting at a light with the foot on the brake and flasher the back up beeper sounds.
6. cruise control works with the headlights out. turn on the lights and cruise shuts off. hit the blinker and cruise shuts off.

I pulled apart the 3 connectors under the driver door area and found corrosion in 1 pin. I cleaned it out and it made no difference.

I pulled apart all the connectors in the back and everything was dry and clean. Put it back together and no change. I disconnected all the back up sensors and it made no diffference.

Not sure where to go next.

 

I disconnected the 3 connectors under the drivers door area, found corrosion at one pin. I cleaned it all up and put it back together and nothing has changed.

 

I also have found that when I have the head lamps on and put on the blinkers that:

1. everything in the front flashes on the correct side only (front bulbs and mirrors).
2. in the back both sides blink and the 3rd brake light blink simultaneously.

I also verified that all bulbs work.

 

I have it fixed now.

I found 3 problems:
1. I removed the harness that connects between the tail lamps and the trailer connector. I did find some water inside the shrink wrap but no corrosion or loose connections.
2. I found a wire splice on the ground on the drivers side, really for no reason. It was in the wire but not connected to anything. I never did this so who knows...must have been something the dealer did. I cut it out and put in a straight crimp.
3. I back probed the grounds starting at the rear tail lamp bulbs and found that there was about 3.6v potential between bulb ground and chassis ground. I traced it through all the connectors and ended back at the connector under the drivers front door. In the forward connector I had already cleaned up a little corrosion on the large gauge white wire which is 12v. I then checked the black wire (ground) 2 positions over and it was 0.05v potential above battery ( I ran a wire from the battery). On the mating side of the connector it was 4.4v. So I cleaned the connector pins and now all works fine.

 

Did you ever find the problem because i have a 2006 f150 fx4 5.4 and everytime i press the brakes are use the turn signals or hazards i blow fuse #2