Hi all, I have a 2005 DAF CF 75 360 - it has a button on the floor to the left of the clutch pedal, which i know is the exhaust brake, it’s just that when i push the button the only thing it seems to do is turn the cruise control off, also if you rev the engine and press this button the engine goes back to tickover until you release the button, whats happening please is there a fuse or a relay i need to check, I drove an identical truck today and the exhaust brake works a treat - you can feel a massive resistance when its pressed what am i missing please thanks lads and lasses