I need legal help with a truck I bought Dec 3 2016. The dealer I bought it through will not fix the problems with it. Now I can't even drive it.

I bought a 03 Chevy Silverado 4x4 truck used for $10,150 on Dec 3, 2016. Two weeks after buying it I started having problems with it. The speedometer stopped working right. The service four wheel drive light came on. It also had other minor problems. I reported the problems to the dealership and took the truck to them on Jan 2, 2017. They only fixed the two minor problems. Now I can't drive this truck because the speedometer is not working. The four wheel drive service light is also still on. I was told by the dealership that they don't have to cover electrical problems because the truck had over 100k miles on it.