Hi, My 1990 Ranger 4x4's 4-wheel drive clicks in but won't engage the auto hubs at the wheels. When I bypass the vacuum hoses on the Auto Vacuum selinoid switch under the right front fender they lock in then. I was wondering if anyone new if it has one and where the relay is for this as I have had no luck finding it in my clymer wiring diagram. The ford site charges big $ for a diagram. This is my nephews truck and funds to fix this problem are at a minimum. If anyone has had experiance with fixing this problem and would help, it would be greatly appreciated, or if you know of a diagram of the relays or wiring of this year I could get from the net it would be very helpful. This is a nice site and it is my first time posting. Thank you so much anyone that has info on this...jack