92 e-350 needs speed control help

[atropine]

I 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?

[phantom_smack]

Do you have brake lights?
Is the deativation switch contaminated with brake fluid when you unplug it?
I would remove that "jumped wire at least temporarily to see if it works.

[atropine]

I have brake lights. I'll look again when I get home, but I think the "jumped wire" connects to a red wire at the harness going into the master cylinder, and also to a red wire going to the deactivation switch. This makes me wonder if Ford originally had a red wire running from master cylinder to deactivation switch, and for some reason the previous owner deiced to cut that wire and bypass it directly. I'll try taking it out, but without it the deactivation switch will surely not be completing a circuit and the cruise will therefore not work, correct? I'll do some more messing around with it tonight...

[phantom_smack]

Have fax ?Pm me with the number.

[atropine]

Phantom-
I PM'ed you my fax #. I disconnected the "jumped" wire last night; no change. If I get home in time tonight, I am going to pull the harness off the deactivation switch and check it out. Unfortunately, the deactivation switch is clear under the cab of the vehicle on the inside of the frame rail, and is very difficult to access. I'm not sure if there is room for my head to get in there and look inside the switch.
Thanks for your help.

[atropine]

I removed the "jumped" wire last night and reconnected the wires in what appears to be the factory original way. I was wrong about the jumped wire going into the master cylinder; I just didn't lean down far enough to see that that whole harness was actually going into the cruise servo control. Anyway, everything is back to the way it should have been from the factory. I looked inside the deactivation harness and it doesn't appear to have brake fluid leak. The deactivation switch appears to be functioning properly. The green wire coming to the switch has constant power, and the red/green wire coming out of the switch is hot except when you press the brake pedal, at which time it goes cold. This seems to be functioning properly.

The horn quit working again yesterday. So now I am stumped again. I checked the clockspring again and it is fine. The ground wire coming into the clockspring from below is properly grounded. When I manually ground the big steering plate (part of the horn apparatus in the steering wheel), then the horn button works. I wonder if I have a problem somewhere in just the upper steering wheel...

I would just take it to the dealer, but none of them will work on it since it is a motorhome. I really don't have any faith that an RV mechanic is going to know how to fix this either....

[atropine]

Problem solved today. Turns out it was a combination of 2 things. First was that the wiring harness was not fully plugged into the servo control motor. I feel like an idiot. It looked like it was fully seated, but it was not. Somebody previous to me has broken off the retaining clip tab that helps hold it on securely. I am going to use a zip-tie to help it stay on tightly, but it held in place without one for a 60-mile trip today. Second problem was an apparent loss of continuity in the wire that goes from the brake override output switch to the servo control motor. This was the wire that someone previous to me had already bypassed. Apparently they had gone through the same trouble as me and firgure that this needed to be bypassed directly. This was the wire I was describing in my original post, and I had removed the bypass wire and re-wired it in it's original configuration. Now that I know this wire is broken somewhere, I just clipped it on each end and did a direct bypass with a new good wire. Problem solved, and everything works great. I even got the new factory recall harness installed at the dealer today in about 10 minutes.

Many thanks to Phantom for his help and guidance with the wiring issues...

[phantom_smack]

I had not heard anything and I was hoping for the best,glad you figured it out !