Peterbilt

Hello guys, I have a 1990 peterbilt, I was wondering if any of you has had this problem.

when I turn my left signal on, it blinks 3 times before it cuts off, the volt gauge also moves back and forth while it blinks. And aside from that, my brake lights also go off and on. Sometimes I have to step on it really hard for the lights to work and sometimes I have to stomp on it. Also when I step on the brake pedal, the volt gauge moves along with it. Anybody have an idea what it could be? It’s really irritating. Another thing is my brake light button pops out on my fuse box down below. It’s a white little button you push in for the headlights to work, tail lights, etc. Please help

 

I don’t think it’s the flasher relay cause sometimes they work and sometimes it don’t

 

I thought the problem would be behind the brake pedal. Is there something behind it that sends signal to truck tail lights?

 

It’s a 1990 Pete 379