The cruise control will not turn on. The CC is Ford factory installed. Horn, all brake lights, abs, hydromax, all work. My unit was not on recall list. I have replaced the SCDS on the brakeline, and I've replaced the brake pedal switch, and I've replaced the brake pressure differential valve warning switch. I've checked all the fuses that seem to have anything to do with brakes and abs. I've found tests to do to the servo wiring harness and those check out. The switch controls seems to check out. No self test feature for the CC on this chassis. Any suggestions?? I don't know if this is related, but in testing things, I've found that I'm only getting about .2 volts through the purple/green stripe wire to the brake pressure valve switch. Shouldn't that be 12v?? Any suggestions are greatly appreciated!!

 

Prob broken wire in the multi function switch in the streering column

 

You already have a an existing thread for this issue. Please do not start yet another.

https://www.ford-trucks.com/forums/1...l-problem.html

The MFS has nothing to do with the speed control system.

 

Thanks for the link to the other thread.

I haven't looked at the diagrams, and I noticed in the link you have a motorhome chassis which may make it difficult to find the correct diagram(Autozone has excellent diagrams for these year trucks) but I believe I am correct in saying yes, you should have 12v on the wire going to the brake switch. I know the older vehicles had a hot all the time wire, but since they had problems and the recall, I don't know if they changed this to a key-on hot wire, but it should not matter if you just turn the key to run and then check for voltage.

What you could also do to make sure you are not going down a rabbit trail, is to take a wire and hook it to the + of the battery, and use it to power the wire that is the output of the switch, and then go for a test ride and see if the cruise works. Double check though, and make sure this is a 12 volt signal in this wire.

 

Thanks for the suggestions. I will give them a try today and report back. Sorry about the 2nd thread to the same issue. I'm a newbie and didn't know.

 

I went back at the cruise control issue today. I re-tested the steel wheel buttons to the servo. Those check out. As stated before the SCDS switch was replaced and that circuit tests good to the servo harness. The brake pedal switch was replaced. Everything works except the CC. I've read posts about checking and replacing a VSS on the rear axle but I don't seem to have have one. From what I could find, the trans has a TSS and an OSS. Could either one of those possibly be the problem? If those were bad would other systems be affected? Short of just replacing the servo and hoping the problem is fixed, am I missing anything? If I have to replace the servo, can any 2003 servo be used? The ford part number is 9C735.

Thanks!