1992 E-350 Cruise not working
just bought a 1992 Winnebago 27' Class C RV which is built on a 92 E-350 chassis. The cruise control is not working. I assume there is supposed to be a dash light that comes on to indicate that the speed control system is powered on when you hit the "on" button. I cannot get this light to come on, and I cannot get the cruise to come on when I drive it. The horn was also not working, so I assumed that maybe the clockspring was bad. Took it apart, clockspring checked out fine on a continuity test. Put the steering wheel assembly back together, now the horn magically works (I didn't change anything). However, still no cruise control. Before I took the steering wheel apart, I took off the center portion of the steering wheel and checked the wiring behind it. There is a light blue wire that appears to go to the cruise buttons, a yellow wire that appears to run the horn, and a black wire that I assume is a ground (I do not have airbags). When I found the horn was not working, I manually grounded the black wire and this caused the horn to work. So I traced the wiring back to the point where it goes through the firewall, and it all looks good. The ground must be working now or else the horn wouldn't be functioning at all. I can't detect any current coming into the blue wire. I have checked all the fuses in the fuse box and power distribution box, but I can't find any wiring diagrams so I am lost from here on out. I know there is a recall on this model's cruise deactivation switch, but I don't think it has been done. It looks like someone has cut one of the red wires coming into the harness on the bottom of the master brake cylinder and run it directly over to one of the 2 wires coming out of the cruise deactivation switch. Don't know why they would have done this, unless it somehow bypasses the deactivation switch. Even if this were somehow defective, it still shouldn't stop the cruise system from powering on, which seems to be my problem. Any ideas on where to go from here?