2014 Fiesta (Mk7.5) Cruise Control

[Lebadoo]

Hi all,

I'm wondering if anyone can suggest to me any further tests to diagnose my cruise control problems.

Cruise control stopped working last week. I don't know if the "on" button is working and the "set" buttons aren't or vice versa as no combination will activate my  cruise control. Plugged in forscan, no DTCs. So, I took apart the switch assembly on the steering wheel. No visible corrosion on any of the contacts. The LEDs on the buttons were still working so I assume the whole circuit board is getting power. Buttons are still "tactile" and pressing as they usually would.

Reassembled the steering wheel and had a look at both of the clutch pedal position switches to make sure they were plugged in and seated correctly which they were. Turned the ignition on and hey presto! All working... For about ten minutes, and then it resumed not working.

Forscan testing showed these sensors working fine (and the brake pedal switches). The "cruise control cancel" option on forscan was only working on the brake pedal - I can't remember if this should work on the clutch pedal too, is anyone able to confirm this?

I looked into cruise control diagnostics but everything seems to relate to the focus cruise control. Has anyone had any similar problems? Has anyone got any further suggestions for diagnosis?

Thanks in advance.

 

 

Edited November 8, 2018 by Lebadoo
Extra info

[pragmatix]

Yes it works on the clutch pedal too.

[Lebadoo]

Thanks pragmatix. Do you know if it also works on the cancel/resume button too?

[Lebadoo]

So the issue has finally been solved after a few visits to dealerships etc.

I upgraded my brake/side lights to a double contact LED. However the LED lamps used the same chips for the brake lights as the side lights (so got brighter rather than working in the way of a conventional dual filament bulb that lights a separate circuit). Thus, when the sidelights were on at the rear, the brake switch circuit would also be receiving current (with the junction being the led chips), thus the cruise control would think the brakes were pressed, and not turn on. Tested it by driving whilst the sidelights were off and sure enough cruise control just worked. It must have been intermittent and stopped working for me when driving at dawn/dusk because of the automatic headlights.