These are starting to creep up again with the cold wet weather and of course when you need it most your 4x4 doesn't work. It all starts with the vacuum solenoid up on the firewall and goes downhill from there. Even if you don't have this issue yet I explain why you should change the solenoid and save yourself from a costly vacuum hub replacement down the road. I also show you how to replace the vacuum hub (IWE) if yours is already damaged.