Cruise control
 

Ok my 86 xj6 is running better ... Thanks to Doug ... Next I'm thinking of tackling the cruise . Where to start???

Depends on what it's doing... Lots of things can go wrong...
Have a look at your bellows, make sure they are in good order..
One thing that is always suspect is the Cruise ECU (Interface), part number DAC3672...
I've seen a lot of those go out..

What exactly is it doing?
Attaching some photos so you'll have something to go by..

Cheers,
David
Everyday XJ

Agreed on the bellows! They often leak; easy to reseal.

Check the fuse, and vacuum hose to the bellows as well.

Post back for details if needed.

Some more in-depth reading:

Cruise Control

Cheers
DD

Appreciate that link, Doug. The cruise on my 87 works in a manner of speaking. It likes to add 10 or more mph to what I set it at, seems to be particularly in love with about 71 mph, and the gas pedal needs a little rub of encouragement to get it to accelerate again once it's reached set speed (or whatever it thinks is set speed) and begins to slow, ie downhill turns to uphill. A little nudge and it gets back on it. The second part I'm rather certain is down to the pedal and linkages needing lubrication and adjustment but the first part, I had no idea the modules had internal adjustments. I'll have to look into that.

Or cable replacement. They often develop stiff operation with age....and doubly so if the engine isn't well grounded.....as the throttle cable becomes the engine ground and this overheats the nylon inner lining.




Yup! But, as I'm sure you know, don't bother with adjustments until you're sure all the vacuum-related aspects of the system are verified as being up-to-snuff....just on general principles.

Cheers
DD

If it's speeding up excessively when you set the speed, it's most certainly the Cruise Control ECU...
I used to take several of the CC ECUs out for testing... Drive a few miles, see how it worked and then swap for another. Very interesting to see how much of a difference one makes from another...

Cheers,
David
Everyday XJ

thanks guys... it does absolutly nothing ...I replaced the bellows ..on a car this old my first reaction is replace things rubber .... I hot wired the solenoids and they 'clicked' I can do again following instructions ... I did put vacume to it with the solenoid closed and it tried to recoil .not very aggressively tho... I looked for split and loose vacume hoses ...easy to miss something. what fuse and where ???? went to site given .wow . I'll try step by step

Hey guys .. I went down the check list and had good results. one odd thing the pulse generator showed 8volts at park then 4volts at drive and held steady at speed . I went back to the bellows and the solinoids checked ohms but did not 'click'. took off and exposed solenoids applied 12v and had to nudge both into action ...lubed as recomended and they seem to b working... next its time for a test ...at 58 mph I hit the stalk and it held at 60 ...YEA!!! when I hit the brakes the cable did not release ..had to reach down and pull back on petal . Ive gotten jag to my shop and unhooked cable , wow!!! it is so stiff I cant get it to move in sheath .. this is a eureka moment ... have ordered new cable ... thanks so much for input and Ill let every body know how it turns out

Will check that cable, accelerator is rather stiff in general, you're probably right that replacement would be the best bet. I will double check everything before attempting an adjustment on the control module but I believe it's in order. It decels, it accelerates with the button, resume works...it just likes to hold a higher speed than I selected. It'll hold 72 mph or so reliably, it's just that I was hoping for 62. :)

xj6 throtle
 

hey guys been a while ..thanks for all the great help . My criuse is working ..goes up 3mph when set but havent tried to adjust yet . the problem with 'sticky' throtle ...I tried every thing lubed up both ends .added ground engine to baody ... took the pedal mechanism out and looked for damage etc. even put in new cable still couldnt figure it out .....Finnaly I rolled up the old cable ,put it into a bucket and poured a quart of oil on it ...let it sit for 3 or 4 gays and put it back in ...works like new !!!! somewhere theres a mechanic ,like Doug ,that would say "every time u replace your throtle or cruise cable u gotta lube that succer"