Ok this is weird my ford fiesta 2004. Firstly while i drive my speedo stops working. and while this happens i notice a voltage drops and the speaker sound level drops lower . when the speedo randomly comes back the the sounds goes back up. The other biggger issue is the car cuts out when i am driving on the motorway at 100km. I just turn the key off while i travell at 100km and turn it back on and it starts up. sometimes is happen once sometimes it will cut out 2-6 times. Took it to fords they think it was teh coil reset the codes charged me and said see if it happens again. Not happy they charged me and had the problem still there. ..... its been like that for a year. just learnt to live with it. But need to fix it now. Is a little dangerous when it cuts out. and p...ses the wife off when she drives. it. PLease help Is

Hi JHAUS , first of all welcome to the Forum.

The speakers dropping may be the automatic volume levelling on the radio activating, it adapts the volume output so that it takes speed into account when driving and increases the volume to overcome road and wind noise.

You should be able to stop this in the radio menu by setting AVL to 0.

Your main problem seems to be the speed sensor (VSS), seeing as your car is (i believe) a MK6 Fiesta it's a sensor on your gearbox

I'd get that checked out, this will definitely cure the speedo drop off, stalling problem and the AVL too.

It looks like this--

and can be a pig to get out, even though it can be done at home i'd recommend a garage does it for you because if it or the mounting pin snaps when you're getting it out then you have a much bigger job on your hands.