Hey guys,
Yes it's dum dum here again, after a good inspection in the engine bay checking hoses and checking all the fuses, i am stumped as to why the cruise control works.....sometimes..!
On driving down a motorway , i flick the switch on the steering wheel, the "Cruise control on " is displayed on the central information center, i get to the desired speed,press the button, but it it does not engage.
After many times of pressing the button or flicking the switch on and off a few times, it will eventually engage. What's going on guys..? why does it take a few attempts for it to engage...?
Any advice is as usual well appreciated.

 

On my '02, the audio control buttons (at the left of the steering wheel) are the mirror image of the cruise control buttons on the right. There's also that rocker switch on each side, too. What I have noticed with the audio is the buttons on the face are intermittent, and don't always respond properly. If I push the center of the buttons, that's when it's worse. I've noticed if I push the edge of the buttons, especially the edge towards the center of the wheel, the response is more consistent. Never had a problem with the rocker switch on each side, nor with the cruise control stuff on the right, just the audio buttons on the left side of the face.

I wonder if your cruise control buttons are acting up in a similar fashion, since they appear to be the same basic buttons as for the audio control. There must be some way to clean them, but I haven't really looked into it. Try pressing a different spot on those buttons and see if that helps. If so, then you'd know it is the buttons that are misbehaving.

 

Funny you should say that,my audio buttons missbehave too, the volume changes the station,... sometimes. As for the engage button for the cruise control, no matter where i press the button it still plays up .But eventually it will engage , it's frustrating.

 

Sounds like dirt in them or they are worn.

 

Possibly... it's bloody frustrating though. I have looked at taking the steering wheel apart to get at them , but it's very dodgy with the airbag bits in there,i would hate to blow my hat off . But when it does engage it works perfect and the response when pressing the resume after braking is awesome it's like a rocket.

 

Don't wear your hat. Problem solved.


I looked on eBay to see how the switches are installed. Search for "Jaguar S-Type steering wheel switches" or similar and you will see plenty of pics. The news is not good, however. The airbag must be removed to replaces the switches. Here's an image, purloined from eBay, showing what you'd see with the airbag removed. Note how each switch pack has two screws, which I've circled in red:




Another stolen image, showing the switch itself:




Jaguar couldn't have made this easy, could they? It's a shame you can't just remove them from the side.

You can test the switches to confirm they are at fault. Wiring diagrams here, see figure 03.4 for V6 models:

http://www.jagrepair.com/JaguarSType...OBDIIcodes.htm


Here's an excerpt showing the switches. The switches are momentary contact. Note the various resistors between the individual switches. All six switches are in a series/parallel circuit connected straight to the PCM, at contacts FH1-56 and -57. When you press an individual switch, the PCM sees a corresponding resistance value to know what you have requested:







With no switch pressed, you should read 2200 ohms between those two contacts, through that last resistor shown at the far right.

Press OFF, and you should see 0 ohms (good continuity).

Press CANCEL, and you should see 120 ohms through the first resistor at the left.

Press SET-, and circuit goes through the first two resistors for a total of 300 ohms.

Press SET+, and now the circuit goes through the first three resistors for a total of 600 ohms.

Press RESUME, and it's four resistors for a total of 1110 ohms.

Press ON, and it's all resistors except the last one (2200 ohms), for a total of 2110 ohms.

I've no idea what the tolerances should be, but it'd imagine it's fairly tight because 2110 ohms for ON is pretty close to 2000 ohms for no button pressed.

 

Thanks Karl,
I understand the steering wheel set up and how to remove the offending switches , but it is the airbag bit that scares me, if not removed properly the air bag can go off ( so i have read) even without my hat on im sure i would lose my head. At the moment it is one of those niggly little issues that gets up your nose for not doing its job properly, but like i said it does eventually engage, and maybe i'm searching an easy fix here , but as we all know nothing on a car can be an easy fix without taking something apart. Anyway thank you for your imputt it is appreciated.

 

Get the workshop manual - free download - and it tells you what to do, including about air bag issues.

 

Cheers Jag V8

 

If all the buttons are affected this could well be a problem with the contacts in the slip ring. This is the part listed as 'cassette' on the digram.

Mellow

 

Good suggestion, but I'm confused about something. In the How-To section, there's a guide to replacing the "clockspring" on a 2003+ model. Is this clockspring a spiral wire assembly, with no "sliding" connections? That's what I think of when I hear the term. Or is it really brushes and slip rings? And are early and late models the same? Perhaps clockspring is accurate for late models, but early models use brushes and slip rings.

It should be easy enough to test the clockspring (either style) at the same time as the switch pack on the steering wheel. While pressing each button one at a time, turn the wheel and see if the resistance changes. Since the engine must be off with the plug disconnected at the PCM, you may want to jack the front end off the ground so the steering wheel can be turned easily without any power assist.

FWIW, my pickup uses brushes and slip rings for the cruise control. The factory manual says to test the circuit by turning the wheel in a complete circle and measuring the resistance. I had to laugh at that, since you never turn the wheel more than an eighth of a turn or so while using the cruise control.

Also, don't be too intimidated by the thought of messing with an airbag. I haven't had to touch the one on my Jaguar, but have done so on several other vehicles. Follow the factory manual and it should give clear instructions on how to disable it. It's really not a big deal. Still, if you're not comfortable with that, you can always pick up a clockspring and/or set of switches and test them yourself as previously described. Then you could have a local shop install them. That shouldn't cost more than a couple of hours' worth of labor.