What my truck is doing when you step on the brakes the park lights on the front come on, the radio dims, and the dash lights come on. Now when you turn on the right turn signal the radio flashes so does the odometer. Could the turn signal switch be the cause,, I have already been cleaning grounds but no change. The truck is a 2000 f150

 

No, it's not the MFS.

You have a bad ground. Start with the ones on the upper radiator support, move to the firewall, then check the grounds behind the left and right kick panels.

 

I cleaned the 2 on the radiator , the 5 on the fire wall. the one on the starter, the 2 under the cab, and the 3 in the kick panels. any more?
Still have the same problem

 

The brake\right signal light circuit is energizing the park light circuit now just to find where.Could be a filament touching in a bulb or wiring.My guess is it's a bulb or a socket on the right side.