Odd cruise control failure and fix

[85crownHPP]

So odd that I wanted to share.

The cruise went out a couple years ago on the 91, and I'm shamefully just now fixing it because I'm taking that one to the festivities this year.

After checking the fuses again, I stared at the ball and scratched my head for a while. I decided to try to give the far side of the ball some vacuum and see if it pulled the cable. I didn't even know if this was a legit test at the time, but it is. I saw the throttle end of the cable move a tad but that was it. So I tried to push on that end of the cable, it moved just a tad too. Cable's frozen? Nope, I took it loose and it moves back and forth.
It turned out that when the cruise cable was trying to move the throttle, the throttle cable's collar/spring assembly that's between the throttle lever and both cables' mounting bracket was cocking out and binding up, not letting the cruise pull.
When I had pulled the cable cover off the ball, I thought the little linkage flopping around looked odd. Sure enough it was an anchor for the mechanism that pulled on the cable. No doubt it broke itself trying to pull on the bound up throttle cable! I tried using my hand to keep the throttle cable strait and pressed on the cruise cable, and it moved freely. For now I just used a zip tie to cinch the two cables together a little, just until I decide to do anything else about it
Luckily I had a newer box model cruise ball in the basement, leftover from when I did the SEFI swap on the 85. I applied vacuum to the far side of the ball again and Vroom! I have cruise once again.

Fair chance this could happen to someone else, so keep it in the back of your mind

[miamibob]

Actually, on my '87 GM the cruise control works but after I set a speed, it drops a few MPH's and then goes back and forth between speeding up a few and slowing down a few. Likely issue and fix???? Bobby

[85crownHPP]

Have you made any changes to it? When I had this ball on the 85 it behaved just like what you describe. Thats why I put the original one back in the 85, with the newer cable. I only took a short ride today but it seems to work fine in the 91...

[miamibob]

No changes at all. Just started on it's own, a few years ago, but since I rearely use CC I never looked into it. If it is an "easy" repair I'd take a look. Maybe vacuum leaks or cable binding??

[sly]

probably vacuum leaks (check the vacuum purge on the brake pedal along with the usual hoses) or VSS wonky.

[gadget73]

The Mark VII used to surge badly, the vacuum dump valve above the brake pedal is bad. i capped it off and it holds speed now, but I don't use the cruise much because I don't like not having a backup disengage method.

[miamibob]

Never even seen that part. Is it difficult to replace? What is involved and wonder if Rockauto has it? Bobby

[miamibob]

Trying to find this part but so far it's a no-go. Anyone got a photo/part number/lead???? Will the one from an '87 Mustang fit?

[Lincolnmania]

Actually, on my '87 GM the cruise control works but after I set a speed, it drops a few MPH's and then goes back and forth between speeding up a few and slowing down a few. Likely issue and fix???? Bobby

i do believe on yours the cruise cable has stretched and needs a minor adjustment

[miamibob]

i do believe on yours the cruise cable has stretched and needs a minor adjustment

Could be as when the CC is on and you tap the brake it does disengage properly. Too bad I can not make it up for the "fest" as it could have been handled. All is well except it needs a heater core but REALLY not up to that project and no big need down here! Bobby

[gadget73]

The vacuum dump valve lives above the brake pedal. If you look at the plumbing at the cruise servo, you'll see one line with a tee fitting, and one side of that tee goes to a hose feeding through the firewall. That goes to the vacuum valve. If you pull vacuum on that, it needs to hold. If it leaks, the dump valve is bad. I believe was a dealer-only item, and its now obsolete so basically when it goes bad, you're screwed. The only work-around for a failed one is to bypass it and remove the safety, which I personally am not fond of. I need to look into working out an acceptable backup system that will drop the cruise out in the event of a brake light switch or fuse failure. I did have that happen, the brake light fuse was bad and the cruise did not disengage. Thats why the dump valve exists, so you can still drop the cruise out if the normal system fails on you.

[miamibob]

Thanks for the info. It is a "dealer only part" but I was able to find it. According to SILVERSTATEFORDPARTS the number is E9AZ-9C727-B. I ordered it from PIFORDPARTS.COM and it costs $4.81 and about $10 to ship it! Not sure if that is the issue or not but for that price it can't hurt to have it on hand! Hope this helps....Bobby

P.S. Supposedly Bob Allen Ford in KS has it also but I never checked to verify.

[gadget73]

They had one? hell I'll have to see if I can get one of those for my Mark VII then. I seem to vaguely recall looking for one before and couldn't get my hands on one. Most of the battle is getting the part number, so I appreciate that info.

[miamibob]

Glad to be of help. Goes for everyone here but you have been one of the folks who has been helpful to me in the past so I am happy!! Bobby

[drhill]

I've been looking thorugh old threads because I am having the same issue with cruise control that you had on your 85 CFI to SEFI swap. I did the same swap and have a ball and cable from an 89 town car on there. How did you solve the bucking with the cruise engaged? SEFI cable with CFI era ball?


Thanks!!

So odd that I wanted to share.

The cruise went out a couple years ago on the 91, and I'm shamefully just now fixing it because I'm taking that one to the festivities this year.

After checking the fuses again, I stared at the ball and scratched my head for a while. I decided to try to give the far side of the ball some vacuum and see if it pulled the cable. I didn't even know if this was a legit test at the time, but it is. I saw the throttle end of the cable move a tad but that was it. So I tried to push on that end of the cable, it moved just a tad too. Cable's frozen? Nope, I took it loose and it moves back and forth.
It turned out that when the cruise cable was trying to move the throttle, the throttle cable's collar/spring assembly that's between the throttle lever and both cables' mounting bracket was cocking out and binding up, not letting the cruise pull.
When I had pulled the cable cover off the ball, I thought the little linkage flopping around looked odd. Sure enough it was an anchor for the mechanism that pulled on the cable. No doubt it broke itself trying to pull on the bound up throttle cable! I tried using my hand to keep the throttle cable strait and pressed on the cruise cable, and it moved freely. For now I just used a zip tie to cinch the two cables together a little, just until I decide to do anything else about it
Luckily I had a newer box model cruise ball in the basement, leftover from when I did the SEFI swap on the 85. I applied vacuum to the far side of the ball again and Vroom! I have cruise once again.

Fair chance this could happen to someone else, so keep it in the back of your mind