For some reason it just quit. The cruise on/off light dosen’t even come on. I’ve checked all of the fuses, and even scraped off any corrosion/residue from the electrodes. No luck. Bought a Chilton book for the car. There’s a paragraph on cruise control but no diagrams, no description to locate components, no help at all. See if I buy another book from them. Where and what do I need to do fix this problem? I miss my cruise control.
On the brighter side my AC blower motor started working again after I scraped every fuse.
Check to make sure there isn’t a brake light out. If there is, the cruise control won’t function.
Tester
All lights are working. If it helps, my horn also went out a short time after the cruise.
Then that sounds like the clockspring under the steering wheel might be at fault. The clockspring works like a tape measure. But instead of a steel ruler, the clockspring uses a flat ribbon of wires. This allows the electrical connections to the controls on the rotating steering wheel to stay connected to the wires that run down the steering column.
Tester
Ok, I’m game. How do I get to it? I’ve tried to pull the front of the steering wheel off (the front cover). That didn’t work. I guess it would, but I don’t want to break anything or have the air bag go off in my face. Not to mention God only knows what else I’ll break in the process. There has to be a trick to get into this. I checked my Chilton book and no help there either. Oh, and are the clocksprings ready to “spring” once I open things up? I foresee a literal can of worms. Also, are they normally carried by most auto shops?
STOP! Do not proceed! Before you even attempt to mess around with the steering wheel, you must disable the airbag. Also, unless you have the proper special tools required to remove the steering wheel, you’re not going to get too far.
Best you leave this repair to someone who has the knowledge and tools to do this. Because if that airbag goes off, you could end up with a screwdriver sticking out of your forehead.
Tester
Well, I was going to disconnect the battery first. Those idiots at Chiltons said to simply remove it, the steering wheel that is.
Even if you disconnect the battery, the airbag can still deploy. There’s a secondary power supply to airbag systems. This can be either another battery or a capacitor in the airbag circuit. Like I said, don’t mess with it unless you know what you’re doing!
Tester
If only I could find someone trustworthy in my area. Believe me I’ve tried. By the way if anyone in NE Texas is reading this, don’t go to Dewey Moore Ford. They’re a bunch of incompetent, thieving, lieing, fools.
I guess I won’t find the cheap way out of this huh?
See if you can locate a good independant shop. Ask friends/relatives if they know of a good honest shop. But ya gotta stop takin’ that ten year old car to the dealer.
Tester
I’m a transplant, and there’s not much to go to around here. Thanks for the help.
I agree with Tester about being very careful where the airbags are concerned. The Chiltons manuals, especially the soft cover, are fit for nothing more than bird cage liner. Maybe.
For what it’s worth, most cruise control problems are generally minor in nature and it’s easy to suspect the worst. Granted, sometimes finding that small glitch can be a bit aggravating.
I also own a Mark VIII (love that car to death!) and I have a Helm EVAC manual. While it does not give all of the diagnostics it does have very good electrical schematics. It’s a bit late tonight to go poring over it because I know it will involve several pages but I’ll gladly take a look at the diagrams tomorrow and see if I can possibly spot something there. Will post back with any possible causes.
If you decide you would like to purchase a Helm manual they can be had directly from Helm (they provide manuals to Ford dealers also) and I’m guessing they’re probably around 40 bucks + shipping. I got lucky and found mine on eBay for 10 bucks. They’re worth the money no matter the price.
Anyhoo, will take a look at my book and post back.
(Note. It’s entirely possible the blower motor and/or the blower motor control module is failing. A worn blower motor can sometimes take the module out or burn the wire connector at the module. I would suggest replacing the blower and this is a job in which the airbags should be disabled as Tester mentioned before you attempt it. Glove box out and you’ll have to remove a number of electronic widgets before the blower can be squeezed out. Little aggravating but not too bad.)
The blower motor is working again. I just had it replaced last year, in the process the Ford dealer really messed up my dashboard, nothing sets in place, they claimed that’s just the way it is. Somehow they also broke my driver seat control panel and tried to hide it with zip ties. None the less, I’m interested on anything you can give me on the cruise control.
Well, there’s a couple of pages of wiring and widgets, go figure! Rather than post an essay right off the bat I’ll throw a few basics out there first and if this goes nowhere then we’ll dig deeper. The “deeper” will require a VOM.
There are 3 power sources involved with the cruise starting with a splice. Since a splice is unlikely to ever be a problem we’ll skip that one. If the horn works, the splice should be good.
There are 2 fuses involved also. One is instrument panel fuse (in the left end of the dashboard) and it’s No. 11, a 15 amp. The other is in the underhood fuse/relay box and is the 10 amp SP CTRL fuse. Make sure both of those are good and that the servo cable is not broken (not likely).
Another possibility is this. Other than the brake switch on the pedal there is also a pressure switch that is designed to open under 5-10 PSI of brake pressure. This switch should be part of a closed circuit until that pressure is reached but a faulty switch or or wire connector could cause the circuit to remain open all of the time.
Here’s where you may need to visit a Ford dealer. Your car should be under recall for the cruise control deactivation switch. Has this recall been performed? Keep in mind that a recall is a pretty narrow thing and may not cover a potential problem entirely.
I got a letter from Ford a while back about this recall on my Mark but simply have no taken the time to have it done yet.
(Kind of amusing letter; “don’t park the vehicle near your house or anything flammable”.) 
Seriously though, you should get this done first if it has not been done already.
If your dashboard problem involves a gap that has developed between the top of the dash and the passenger side airbag (above the SRS logo) this may not be the dealer’s fault. It gets hot in TX (likewise here in OK) and sheer heat will cause the gap to develop. It’s not that rare a thing. You may also expect the vinyl on the top of door panel near the door glass to curl over time also.
A dragging blower motor can knock out what is called the blower motor speed control module so if you have an erratic blower motor that could be the cause.
There is also a self diagnostic that can be run on the EATC control unit. If you’re interested in that let me know and I’ll post the directions. The same applies if the cruise problem does not turn out to be one of the fuses or the brake switch problem.