I would think adding a resistor to two of the 3 wires coming out of the servo would sloe down it's function, but i wouldn't even know where to begin to figure out what the values would be. Seems like one of those things where it will need to be trial and error. If i had to guess where to start, perhaps another 25-50K ohms of resistance?
It's an 89 with the yellow one. It was 5spd swapped by the previous owner and still running the A9P ( In case that helps you find a pattern)
Most everything on the car is still original (or very old dealer replacement parts)
Wow lot of great info here, my cruise control broke over a year ago and I couldnt find any info on this subject, thanks loads.
In regards to the amplifier I pulled one from a junkyard a while back and its black but cant remember the year i got it from but i think it at least was an 86(mines a 90LX and has a yellow amplifier) The one i pulled from scrap dosent have an id sticker(i can see where it used to be) and no part # that i can find in the molding. Do we know if there is any difference between the amplifiers? Or is it at least safe to hook it up and try? I want to start there. it seems like changing the amplifier and plugging the vac line thats at the pedal assembly seem to be the easiest first steps in troubleshooting the cc.
that's not troubleshooting, that's replacing random parts, the only similarities are it's a mustang part for cruise control.
There are Ford repair manuals out there or a member here (if it were not posted here already) can post a page from the diagnostic page.
I was never able to find any info on the differences between the various amplifiers. I imagine the differences are tuning in the rate at which the cruise corrects speed, min speeds it will activate and other vehicle-specific criteria.
Just a guess. I assume to find out those details would require someone from Ford who has access to the specific programming who can explain differences. I doubt that would exist