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(it's a 2.2 TDCI estate, mk3, 55 plate)
Cruise control has stopped working... Already ruled out clutch and brake switches (clutch switch registers correctly on Formiddable, brake switch runs the lights). The cruise control logo appears on the dash on startup then goes out, like normal, though I don't know if that's relevant.
So that leaves... Steering wheel switches, actual cruise control brain whotsit, and possibly fuse? If it's the control module then I'll not bother I think...
Anything else I should consider? Or useful diagnostics? If it's switches, I can't think of any way to distinguish whether it's the cruise control master on button on the left, or the button on the right that controls it once on, is there any indication available when the system is switched on but not currently cruise controlling?
Cheers folks!
PS, I noticed it had failed at the exact moment I passed through 111111 miles on the odometer, and so became convinced that the car's whole electrics had shit the bed and blanked out the console. This lasted for ever so slightly less than one minute 
Wheel sensor fault stops the cruise control working but would normally show as a fault. Assume the brake light on the dash lights up with the ignition then goes off again.
Also the throttle position sensor can stop it working. Never had to sort this but usually it just needs cleaning.
TPS makes sense. I'll check the brake light tomorrow, cheers!
Wheel sensor is an interesting one, ABS sensor do you mean? I changed a rear wheel bearing shortly before so that'd be a logical fault, though there's no fault codes or abs indicators etc (and the abs is definitely working, found some ice on the way to work today!)
TPS would be where I'd start. There may be more than one. My Volvo's got two. One of them was faulty from new & caused the CC to work intermittently. There may also be connectors to & from the TPS (or other sensors) that could cause this.
Good luck, D.
Wheel speed sensor / ABS sensor same thing. If one is faulty they clear themselves but come back again normally shows with the Brake/ABS being lit on the dash. When it is lit it shows on the F-super software of which sensor is at fault. If you still have the faulty hub use the sensor from that as it will be a Bosch part were as the pattern parts hub will have come with a cheap nasty one.
Clutch switch was the cause of failure on my Audi. Mondeos may have a similar switch, as dipping clutch or brakes will deactivate any cruise control. 10 minute job swapping switch under dash/on to of clutch arm. No warning lights ever came on, and the switch only activated/deactivated cruise.
Vacuum hose/ pipe off somewhere or is it all electronic?
Clutch switch is definitely working. (the f-super/formiddable software has a real-time read and picks up correctly) So I think safe to discount. Though I suppose it wouldn't take 5 minutes to eliminate completely... Might be worth a poke!
Inclined to rule out the hub, for the moment at least since there's no codes- though it's a nice match otherwise so I'll keep it on the backburner. It's a nice EBC one rather than a pikey pattern one fwiw, I figured I'd trust my wheels more if the hub cost more than a pound 😉
Everything else seems to be operating normally so I don't think there's something kind of [i]infrastructury[/i] like a vacuum hose.
You know, I came in here to narrow down suspects not to gain extra ones! Helps me think though so cheers... Throttle sensor seems a good one.
Hmm. Seems unlikely to be the fuse as it also runs the aircon. Then again maybe it just runs the cooler, which I've not used since.
Seeing as the CC on the Volvo and Mondeo is probably the same kit, Davesport's suggestion sounds very interesting.
Would you not expect other issues- erratic throttle response etc? Will give them a clean on general principles though.
Completely different vehicle but my van has two brake pedal sensors, one normally open switch and one normally closed. I believe both are required for the cruise control.
It definitely won't be the TPS as that would affect normal running.
The ECU has two brake inputs- one normally open the other normally closed. The most likely fault is one switch is broken - most likely the one that doesn't do the brake lights.
Do you not have a method of reading the fault codes?
There isn't a cruise module, the switches are a resistor network that go to the ECU via an analog input
Yep, have read codes with F-super/formiddable. It does realtime reporting too so confirms normal read from the brake and clutch switches but that's interesting about the 2 switches- didn't know there was a duplication, and it could easily be that only one gets read by the software. So that's another one for the list, cheers!
Also good to know about the method of control- I like that, I could make one myself
when mine stopped working, it turned out to be the clock spring which is beneath the airbag on the steering wheel. It cost £20 from a salvage yard and an hour of time to remove and refit.
Common problem
Ah, cool- does that not normally throw fault codes/dash lights? Or maybe only does that when it's affecting the airbag?
Still haven't got my finger out on this one so cheers for the input!
Plug it in if you can. On mine it was a early warning of death. Something I wish I'd paid attention too.
First thing I'd check though would be plugs into steering wheel. Work cheap then move too hard. Scrap button and bag unit from a breakers will only be 10-20 and then I'd try the fuse. As CC fuse is behind the glovebox. And can be a bitch to replace.
El super late follow up... It was the passenger side windscreen washer heater. Obviously I diagnosed this the way any bodger would- after blowing a couple of replacement fuses, stuck in a higher rated one and waited for some smoke 😆 Amazing how fast you can get the sound baffle off the bonnet when you want to.
So I now have cruise control, and one working washer heater. And hey, possibly a working booster heater. This is an upgrade
Well of course that's the first you should have checked and now go and hang you head in shame for not checking the basic first.
Do the washer jet heaters and cruise control share the same fuse?
They do- tbh I'd ruled it out because I thought the washer jets were also on the same fuse and they work fine 😳 Also because the aircon is on the same fuse, and it seemed to work correctly, but it turns out that it's only the cooler itself that uses that fuse, the fans, heaters etc are all on a different circuit. And I'd not noticed any difference in heating performance either and the booster heater runs off the same circuit too. So basically massively overthought it!