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Cruise Control went out a few months ago. I've searched the forum and couldn't find my unique symptoms. Hopefully someone can point me in the right direction...
1999 F250 SD v-10 185k
While driving I turn cruise on and hit the set switch which illuminates the light but not cruise.
I thought maybe the clock spring but the horn still works?
Differential speed sensor replaced two years ago and appears to operate fine; no codes or problems with shifting or speedo.
Took cover off servo...no corrosion, gears move, shows power, cable is NOT in a bind and is connected to linkage? There is voltage between servo harness connector terminal No. 7 (Light Blue/Pink wire) and terminal No. 10 (Black wire).
I replaced master cylinder pressure switch and have power. Recall pressure switch harness was replaced before I lost CC.
Brake lights and horn work.
Diagnostic test turning key while pressing OFF cruise switch. Light blinks once with OFF and one with ON but does not illuminate pressing the other switches (resume/coast/set). From these diagnostics I would guess the resume/coast/set switches are bad but then i'm puzzled that the cruise light works while driving and pressing set button.
I don't want to just throw parts at it. Any ideas would be greatly appreciated.
cr295, you did not say if you had wiring diagrams or not.
I don't have the 99, but I do have the 2001 schematics and I have included the two that pertain. Maybe they are basically the same.
Since all the cruise switches go thru the same clockspring, it should be easy to tell if they are working by metering.
I would first check all the signals that go into making sure the servo control module has what it needs, +12V and grounds, then go from there. Note that +12V is also needed thru that brake pressure switch to make it work. If all the signals into it seem correct to make it go, then maybe the electronic part of the module is bad.
I thought i would post a follow-up to assist others troubleshooting similar cruise control issues.
As Tom (F250mtnbiker) surmised it ended up being the servo.
This is a pricey part at the dealer, 400 bucks + -. I went to ebay and found a "working" used one out of an 01 Excursion. 12 bucks and 4 days later my problem is solved. The bracket and cable were wrong for this but it's very easy to swap out whats in the truck to the new module. Basically almost any Ford 10 pin servo from a Ford car or truck will work if you swap out the cable and bracket. I don't know the specific years or models this applies to but the servo in my 03 Taurus appears to be exactly the same.
At first glance the old module's drive motor is apparently burnt out.
I will try to get pics up of the inside of the servo so others can possibly benefit from my woes in tracking the problem down.
