I have the "cruise control unavailable" message, and I understand that the adaptive cruise control module is prone to internal corrosion. My 2004 XJR has 55k miles on it and the module looks extremely clean and totally uncorroded on the outside. SDD only suggests module blockage or failure.

1) Does anyone have experience of adaptive cruise control modules that look great on the outside, but are corroded to failure on the inside?
2) Is there a way to test the module it's self without taking it apart.

Thanks all.

 

The adaptive cruise system relies on the brake switch CONSTANTLY being de-activated in order to work properly. My car occasionally gives the "Cruise Unavailable" message and I have found if I furiously kick the trim panel above the brake switch under the dash it fixes it...for a while. It seems that if the switch is slightly wonky and gives an intermittent signal, the cruise system throws a fit and shuts down. One day I will get around to replacing the switch. I would look into this as the culprit before I start ripping into the module.

Good Luck
Jeff

 

Thanks Jeff. I went ahead and ordered a new switch from Amazon for $15. Hoping 3M5T-9C872-AB is the correct one. My brake lights are working fine and SDD is not telling me about any switch problems. Assuming the same for you? Won't be able to change the switch for a while as we are snowbirding after Christmas. No fun working under the dash, but definitely better than trying to fix a module that ain't broke.

 

Sounds like a good place to start
Switches will sometimes work.
When disconected then reconecetd again.

 

Finally got to this, but it did not fix it.

 

I have dinked from time-to-time with trying to get mine fixed on my 04 R for about 15 years now. I replaced the clock spring to no avail, but now I have a spare. I, too, will try the brake switch. I am getting some kind of brake light code but otherwise, the brake lights seem to work fine.

I was going to spray the switch with some WD40 because someone on another thread said that fixed his. However, I couldn't find the dang switch! Can you share the part name & number you ordered?

Thanks, best and have a great weekend!

Steve S.

 

Hi Steve,

look here, you need item no. 8:

https://parts.jaguarlandroverclassic.../brand/jaguar/

Best regards,

Thomas

 

From the guy who brought you Jagdroid:
"Jaguar XJ X350 Adaptive Cruise Repair" https://sites.google.com/willcoxonli...air?authuser=0
(No, his did not look clean from the outside.)

 

Thanks, Thomas! Great site.

Jaroslav, what an amazing thread. Makes me wish that I had yanked mine while the fender cover was off. Next time!

Best,

Steve S.

 

@Dagenham Dave and Steve,
It's just behind the black pop out panel LH lower grille. Easy to get to. But, if it is not the brake switch, be sure it isn't a wheel speed sensor. They can be intermittent and a pain to trace. The ACC would be the last thing to tackle.
I have also read on the forums, XK150 anyway, that ACC runs separately from regular cruise. Working from memory here, disconnect the ACC box, then use SDD to tell the car ACC not fitted. Regular cruise should be available then. I'll post the link if I can find it again.
https://www.jaguarforums.com/forum/x...screwed-94999/ Read Cambo - he's good.
Just search the forums for ACC bypass. One poster said the DSC feeds through the ACC, the DSC plug would need to be jumped across the ACC. Diagram and illustration provided. Here - https://www.jaguarforums.com/forum/x...assing-223927/
You could also get the P/N from yours and try to find one on ebay. NOMA Auto Parts may be a good source.

 

Thanks, Luv2fly, very helpful!
Have a good week,
Steve S.