intake manifold flap keeps running

[daddygez]

Hi Guys.Battery keeps going flat on daughters 2003 Mk IV 1.9sdi t. the intake manifold flap motor keeps switching on and off even without the key (that's probably why the battery runs down). The glow plug light flashes constantly and there is no power to the glow plugs at start up (all brake lights work!) I'm loath to purchase a new flap at £200+ in case it's not that. OBD checks as no faults.
Can anyone point me to a possible solution?
thanks Gez