My Fiesta is five years old and has sync with the Sony DAB radio/navigation. At about 2 years old the voice control button started working intermittently (such as only at certain steering wheel angles) and the dealer replaced the button assembly. All good since then.

In the last two weeks it again worked intermittently briefy (on one occasion I had to press the button three times) then stopped completely. Different on this occasion as it failed quickly which makes me think there is a disconnected cable. There is no noticeable difference between how the voice button feels and and the cruise control on/off button so it doesn't "feel" faulty.

I have already tried:

1. Sync upgrade to the latest version via the Ford download site (and all the hassle of editing the faulty text files!)
2. Powering on/starting the car with the voice button held down
3. Full factory reset of the sync module
4. Removing the fuse from behind the glove box, confirming sync was unavailable, putting fuse back in.
5. Re-pairing the phone with Bluetooth (it's the same phone I have had for years so not a newer phone compatibility issue)

None of these have coaxed the voice control button back to life. All the other steering wheel controls work flawlessly.

I understand that the buttons work by resistance being measured via a clockspring. What happens after that I don't know, but I assume there will be a cable from whatever module measures this resistance to each of the modules that control the various functions.

So my main question is, is there a specific cable that routes to the sync module that may have worked loose and become disconnected. If so, where are the A and B ends of the cable located, and indeed where is the sync module located, behind the dash somewhere or in the engine bay?

Secondary to this is there a button on the Sony unit that can be pressed as an alternative to the steering wheel control to activate the voice function? I can still control the phone from the centre console via the menus, select a number to call etc, just can't start the voice recognition.

Thanks for any advice!

The buttons work by each sending a different resistance voltage to the designated module. The clockspring permits multiple wires to pass through the steering columns from the wheel. 

It’s often a case of a dirty/stuck button if you’ve tried all the reset options, or as you say, a loose connection. Try spraying with contact cleaner first. If that doesn’t work you can take the V trim off by taking out the 3 hex screws on the rear and seeing if the connections are firm. Also check the cables into the sync module under the kick tray under the glove box and in the steering column (see photo). 

If that doesn’t work get a new switch module off eBay or the like.

Great advice, thanks. I will take a look and report back.

 

It will be the switch again. I replaced my partners 16 plate fiesta switch a few weeks ago. 

All of The buttons on mine have been dodgy since I bought it when it was 9 months old (I don't have cruise). sometimes if a button does not work I press other buttons. Once one works they all seem to start working again. As mentioned above all the buttons work by having a different resistance setting. On mine it's like the radio cant determine the command but if i press other buttons until one works it's like it resets itself and they all start working again. 

I had a slightly different experience before Christmas. Everything was fine until the voice button had a single moment of strange crackle/noise and stopped working. All other buttons on the same pad worked perfectly.

I tried to spray some WD-40 Specialist contact cleaner into the button area but it didn't make any difference. Tried resetting, fuse and re-pairing all of which made no difference.

In the end I left it until I had my car in for MOT and Service at the beginning of March and asked the Ford garage if they could take a look (expecting a possible new switch to be the problem). Not entirely sure what they did but apparently they 'reset the system' (exactly what I don't know) and it has been working perfectly since.

The voice control on my fiesta mk7 stopped working,  after having work done on the car, which required the battery to be disconnected for a period of time. 

Any suggestions as to remedy this, would be appreciated. 

Intermittent voice control and volume controls on steering wheel working, then none at all. Removed volume control unit from steering wheel (as shown on YouTube), dismantled it by unclipping layers. Cleaned all contacts using cotton buds and contact cleaning fluid. On replacing it all now working fine including voice control (which is on a separate control).

14 minutes ago, Robert the Bruce said:

Intermittent voice control and volume controls on steering wheel working, then none at all. Removed volume control unit from steering wheel (as shown on YouTube), dismantled it by unclipping layers. Cleaned all contacts using cotton buds and contact cleaning fluid. On replacing it all now working fine including voice control (which is on a separate control).

p.s. There was no need to remove the air bag, just need care when removing the clipped in silver ‘V’ insert.