orange turbo light

[martinworswick]

whilst i've got my hands dirty and the bonnet up i may as well make the most of it-
when i'm driving, if i put the accelerator all the way down to the floor i lose power, both lights come on for the turbo when i turn on the ignition, the green light comes on when the boost kicks in and you can here the turbo whining but the orange light never comes on and i never get the extra boost.

any ideas?

cheers in advance