zafira heavy steering

i have a zafira 2ltr dti 2001 and recently the steering seems to gone a
little bit heavy sounds strange but seems uneven i have checked the
power steering oil and tyre pressures but i have also noticed on
tickover when you turn the steering the headlights go dim and you can
also notice it on dark nights whilst driving you change gear and the
revs drop you can see the headlights go dim and the dash light aswell.I
think the power steering works on an electric pump so could it be an
electrical fault also ssomeone has said the belt might be loose but i
have checked this and it seems ok but if it was loose wouldnt it squeal


all help appreciated

 

Pumps are electric so no belt to worry about - pump is fed from the
alternator so - no charging = no pump operation.
Check the main earth for the pump - near the near side bonnet hinge - a 13mm
nut. Make sure the rack is dry and not leaking oil.