electrical problem
 

have a 03 f250 with flatbed i have 4 led lights in rear that flash rapidly i tried a heavy duty relay but made them flash faster. now my turn signal relay will buzz the whole time the truck is running it will stop if you use turn signal or hazards or when you apply the brake. now in park the speedometer is moving up and down while running???? can some one help thanks for your time

the led lights dont draw very much electricity, you can add resistor or run 'lighter' flasher