As my cruise control does not work I read something could be wrong with tha cables.

I looked and fixed them.

No cruise control at all. What else can I do to check it?

 

Check adjustment of disengagement switch on brake pedal.

 

The rubber bellows in the cruise control module under the hood, around the cowl area, is more than likely dry rotted with holes in it.

Another possibility is that the hard plastic vacuum lines under the hood have a hole in them. Could be both.

 

It's on the other end of the cable going to your throttle. (I think) Can you take a pic of it? It should have a small, rigid black vacuum line to it, that has vacuum.

(I'm in the process of figuring out mine on my 90, doesn't work, as well)

 

I can take pics tomorrow

 

where do the cables from the lever go to? Is there a conection under the dash? Cannot find it.

 

Mine doesn't work either on my 92. I have replaced vacuum lines and checked wires. Still can't figure it out

 

On the stock Renix era MJ/XJs the wires from the cruise switch are connected to a yellow box (cruise control electronics) that is mounted directly below the steering column right at the front edge of the dashboard. Also on the stock CC, the wires go through the stalk of the combination switch (CC,wiper/washer) into the steering column housing, then to the CC box. Hard to tell in your picture, but I'm not sure that yours is stock. At the very least, it has been tampered with.

 

His looks like stock wiring colors and gauge, but they have definitely been chopped on. You can see the heat shrink tubing. And they are exposed out of the steering column.

 

I will search this box. Thank you. I welded the cables as they were broken...and it has stock cruise control

 

the small line has vacuum. when I pull it of you can hear it...

 

I checked the vacuum line to the canister and back to the servo. all fine. When I pull of the little line you can hear air coming in.
The plastic piece at the end of the cable is connected to the throttle. than a big line goes into the firewall (no idea where)
The cables at the level were broken and I repaired them.
Under the dash the cables go into a connector and in a yellow box.
What elese can I check or messure???
How can I check the brake switch or adjust it?

 

You should have a 5 wire plug to your servo. 3 of those wires do the regulation of the throttle.

If you disconnect the wires you can test the solenoids.

Put power to the orange wire. Then ground the white wire. You should hear a click.

Ground the red wire, again you should hear a click.

I forget what the combination is, but you can figure it out easy.

Start your rig. Put power to the orange wire.

Then ground the white wire ***BUT BE READY TO DISCONNECT THE GROUND IF YOUR RPM'S START CLIMBING!!!!****

If the white wire didn't do it then ground the red wire. Be ready to disconnect the ground to bring your rig back to idle.

By default, when you remove power from those solenoids ALL vacuum to the throttle is released.

It's not complicated to test the servo.

The ONLY reason I know this is because I am currently in the middle of installing an idle controller with a re purposed cruise control servo from a 1989 XJ.

 

Great info thanks a lot! Will test it like that. There must be a test to the 5pin connector on the carside, too. Is there any wiring diagram for a 1990 4.0 that I can use?

 

You might actually have to activate BOTH solenoids to get the throttle cable to start pulling.

If you can't figure it out I will be finishing my retrofit soon and can double check which solenoids do what.