Bought when this first came out its just been sitting on my shelf but it never came with a harness I might can find instuction but all wires just PIGGY BACKED on E.C.M wires, I thought they all were like that..??And yes it can be re-programmed, Eric from TT is were this came from and they still sale and work WELL I just went to a F.A.S.T... oh and I have 2 chips to go along with this unit..