Hello Chaps!

I know this is an often discussed topic, but I've got an unusual symptom I've found that doesn't appear in any of the threads I've searched.

My Failsafe message comes up normally when I'm on the motorway and using cruise control. It normally comes on when I have to cancel the cruise to brake or anything, then I notice the light has come on and I've lost the cruise control. This doesn't always happen on highways, it can happen on normal roads, when I've left the CC master switch on.

Now I have found that if I continuously tap the + button on the steering wheel the speed does hold, but gradually drops as I can't tap fast enough to keep it at say 50mph. I've also found that switching the engine off and on again resets it and kills the light for a while.

But now I've noticed I'm not getting any sense from the CC whatsoever. Even with no Failsafe message the system is temperamental. I've just been on a trip where I covered 350 miles, and about 250 of those were on the motorway. The car is a 2001 4.0 XJ and has done 96000 miles.

Any ideas would be most appreciated,

Thanks Guys!!
Stu.

 

Do a search I think you will find a failsafe related to the brake when the cruise control was used or turned on. I think one problem was related to the brake switch and the other was a vacuum leak I think.

 

I have seen these exact same symptoms caused by a faulty brake light switch.
There are two microswitches in the brake light assembly, one for the brake lights and one for the cruise control, the contacts in the one for the cruise control go high resistance and cause the symptoms you describe. The brake lights are not affected.

 

I have the same problem when hitting resume after canceling the cruse to stop at a light at about 35 to 40 mph the car loses power and the fail safe comes on...same thing power down and up and all is good until the next time...the jag dealer says humm haven't heard that b4 but will check on it...

 

I vote for the brake switch being faulty
Here is a TSB from years ago!!

bob gauff

 

Thanks For the replys!! So I'll check out the brake switch then, I reckon I may have damaged it when I had to do an emergency stop for a blind old man who just pulled out in his rather large Nissan Jeep thing... o.O

Is there a way I can repair the switch or will I need it replacing? I can do the job myself of course. I've elected to spend an entire day fixing all the "little things" I've been putting off on my next day off. Thanks for your help guys!!

 

Try this likn to the switch. http://www.motorcarsltd.com/LNB6420BB.html

 

Great post. Thanks for all of the good info!

 

Get a brake switch from a breaker, about 15 quid. Easy to fit.