Hi, the cruise control function and engine brake have stopped working completely, they have worked on and off for a while now. The truck is a 2002 Volvo FH12.
Has anybody come across this problem before? thanks
Are your brake lights working correctly?
Hi, yes brake lights are fine.
There is a toggle switch on the left hand stalk! Is it on or off? Also when you drive away after being stationary if you haven’t depressed the brake pedal your cruise wont operate straight away!
Your engine brake is a switch on the dash next to the airvent to the left of your steering wheel! It has a lip in the middle of the switch! 
Could be the position sensor on the clutch,brake or accelerator pedal 
I have a feeling it could be a sensor too, might be a job for Volvo dealer
just a long shot but have you checked the fuse before you go to the volvo stealers.
Hi,i had it on my fh and what i did when it happened was lift the clutch pedal up and it would start to work.
i’ll check fuse and try lifting clutch then, see how that goes, thanks