Flashing Glowplug Light

I had the flashing glowplug light come on today , It resets if I stop and turn the engine off , but will come back when accelerating under load, 2.ltr CR diesel with 80,000 miles , took it to dealer they said no code listed so they want it in for a day. I have read the posts relateing to this fault, I have checked the brake lights ok, there is mention of checking some hoses for spliting, I have no idea which hoses they mean , could any kind person please help with the location of these hoses. Many Thanks