Hello I wonder if anyone could help me I recently brought a 57 plate ford focus st the car is perfect :) but just one thing is really bugging me when driving along at night the radio seems to go bright then dims it self?? Also the dash dim switch doesn't seem to work. Anyone know what this could be?? Many thanks tom

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Sounds like a dodgy rheostat in the light switch.

May need a replacement switch.

I'm assuming front fog lights and self levelling system?

If so then this one will fit-

http://www.ebay.co.uk/itm/GENUINE-FOCUS-HEADLAMP-HEADLIGHT-FOG-LIGHT-SWITCH-4M5T-13A024-HA-2003-2008-/160921824759?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item2577b02df7

Hello thanks for your reply that is the switch :) so that is most probably the fault then?

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The dimmer switch is just a variable resistor (rheostat) that reduces or increases the voltage through the various illumination circuits, as in your case the radio and dash.

The switch could be dismantled to try a repair, but why fiddle around opening a unit and poking around scratching your head when a replacement is so much easier and probably much quicker.

If you need help with swapping around a switch I do have a guide from where I swapped out a non-dimming switch for a dimming version.

http://www.fordownersclub.com/forums/topic/32195-fitting-a-dimmer-switch-to-a-mk225-focus/

make sure you get the right part number ..earlier ones are green illumination ..mines a 2007 model and i have red illluminations