Truck Aux input goes in and out...?

-I'm not sure whats wrong. I know my speakers on my truck (10' Ram) work, and I know my iPhone works... so either my aux cord is broken, or my aux input is broken. If I mess with the wire by changing its tension into either the phone or the truck it works, but if I move it slightly it doesn't work at all... Is it most likely the input on the truck or the phone, any help would be great....It's your AUX cable... They split inside after a while do to constanly moving around... Just get a new one and you'll be fine