ABS adjustment
 

My abs braking system is ineffective on icy conditions when the temperature is near freezing. I went through 2 intersections before I took out the manual and found I could pull the fuse on the system, and have manual braking, which works very well. This truck has been to the dealer twice for this problem, and yet thebraking staysthe same. I'm wondering if the ABS unit can be adjusted, or if the factory setting is permanent?