XJ Cruise Control Experts Needed

[AZJeff]

As my sig. line shows, my MJ actually has a 2001 XJ engine control system in it.   I have been struggling to figure out why the cruise control does not work, and have been chasing wiring and replacing parts with no sucess.

 

I need the help of an "jedi master" on the cruise control systems used in the later XJ vehicles.  Can anyone recommend someone either here, or on one of the XJ forums, that I can talk to and pick his/her brain about how to diagnose my issue correctly?

[Dzimm]

There is something funky about the buttons having to be from the proper year.  There are I think 3 different versions of the buttons that send different electrical signals depending on the years which I believe are 97, 98, 99+.   

 

Did you get everything from one donor or multiple?

[AZJeff]

I don't know for sure what year the original buttons came from (either 2000 or 2001).  The replacement buttons I put in came from a 2000, and changed nothing about the behavior. The PCM came from a 2001,  but has been refurbished by an independent shop in the past, so I assume it was from a 2001 originally.

 

Here are the exact behaviors:

 

 

 

 

·     When the switch on the steering column is pressed to turn the cruise control “on”, the light on the instrument panel saying “cruise” comes on. 

·     However, as soon as any controls are touched (including brake or accelerator), the cruise light goes out, and of course, there is no cruise control function.

 

 

I have used the FSM to chase down the cruise control system wiring.   Here is what I have done so far:

1.   checked all wiring between PCM and servo.   Checked all wiring between PCM and buttons on steering wheel.  Checked all wiring to brake light switch.

2.   replaced servo with new Mopar unit

3.   replaced clockspring (due to horn issues, but it also feeds cruise signals down column) with new Mopar unit.

4.   replaced switches in steering column (used, but checked out the same as old ones with ohm-meter)

5.  sent PCM back to original repair shop, who reports "no trouble found"

 

What's next?

 

 

 

 

 

[Dzimm]

Since you've already traced everything out I would do more research into the buttons.  I don't know all the details off the top of my head anymore but I recall people having similar issues due to the different years of buttons.  Id imagine your experiencing a compatiblity issue of some kind

[75sv1]

The buttons are 97-98 (possibly 96-98) and 99-01. 

[schardein]

I used to own a 2000 XJ.  Added cruise using junkyard parts.  Didn't work, and it was because the switches weren't the right year as others have stated.  Went back to the junkyard and got the correct ones, and it worked flawlessly.

[AZJeff]

I am guessing the part numbers are different for the early and late switches.

 

Does anyone know what are the correct part numbers are for a 2001 XJ cruise control switch group?  I guess I could ask the dealer....

[Limeyjeeper]

AZ Jeff See attached.

2001 XJ Speed Control Part Nos Switches.pdf 2001 XJ Speed Control Part Nos.pdf

[AZJeff]

49 minutes ago, Limeyjeeper said:

AZ Jeff See attached.

2001 XJ Speed Control Part Nos Switches.pdf 107.92 kB · 0 downloads 2001 XJ Speed Control Part Nos.pdf 91.37 kB · 0 downloads

You are my new best friend.  THANK YOU!!

[Limeyjeeper]

Any time, this is what the forum is for!!