i have a 1997 gm2500 pickup. lately if i turn on my left blinker the blinker works in the front but in the back both left and right blinkers turn on. My amp-meter also drops every time the blinker flashes. On the other hand if i turn on the right blinker it flashes quickly in the front but nothing in the back. i thought maybe the switch its self was bad so i replaced it, still no change.

 

anyone have an idea?

 

The brake lights are the same bulbs as the turn signal bulbs unless I'm mistaken. Do the brake lights operate correctly? Do these trucks use a relay to control the brake and turn signal operation? If so, I'd get a replacement relay to switch out the old one.

If that doesn't make a difference, I'd see if there was a messed up trailer wiring harness.