Are you sure that the ABS is the cause of the front wheels locking? I ask this because this is the first time I have heard of this and I have worked on many ABS Systems since 1985. Are your front brakes in really good shape? have you checked that the pads did not become dislodged and are grabbing in an unusual way ( common ) As for disconnecting the ABS, this is a safety issue and with a pickup truck in a cold area, this could be VERY dangerous, because there will not be any control over the rear braking. the ABS mostly controls the skidding on the REAR brakes on a pickup, because the bed tends to be really light weight compared to the front of the vehicle with the engine and your self.