Steering: How should "Servotronic" steering feel?

[tdi]

Replace the fluid before anything else.

[Moose Test]

An update, on the basis that it might be useful to others experiencing similar symptoms.

I did get to drive an 11 plate R-Design for purposes of comparison and yes, there is a night vs day difference between it and my own vehicle. Clearly my speed sensitive steering, isn't. I couldn't believe how light on the steering the R-Design was, driving it slowly around the dealer's forecourt.

As most threads here on steering faults routinely feature the recommendation to flush and replace the hydraulic fluid, I did this pre-Christmas. It has made no difference whatsoever.

My car's symptoms are:

1) The steering is consistently and permanently heavy. This is more noticeable of course, at low speed. There are no intermittant periods of normal function.

2) The steering is smooth, with no 'notches' or differences in force required at certain points, or extremes of travel.

3) There is a slight buzz from the engine compartment when on full lock sometimes, but not always, and never that loud.

4) There is no improvement at low speed if I suddenly increase engine revs, to work the pump harder.

Since I don't have the equipment to carry out pump pressure and capacity tests, I started with electronic diagnosis. The power steering steering control module is powered-up and shows LIN bus activity however the solenoid valve on the rack is reading open circuit (as measured at the module's socket). So either there is a wiring / connector issue, or the solenoid's coil has burnt out.

I don't currently have the facilities for safe working under the vehicle, so I've booked it into my local Volvo dealer for examination of the solenoid and its wiring. Fingers crossed, this will amount to no more than the need for a replacement solenoid. However I guess it is also possible that a solenoid failure might itself be symptomatic rather than causal.