Your problem looks like is going to be a faulty power steering moduel. Have the shop look up tech journal #18036 Here is a description of the tech journal.
Customers may complain of intermittent low power steering assistance on vehicles with speed sensitive steering. After cycling ignition key, the steering assistance may then be normal. This does not affect the hydraulic power steering system and only affects the electronic assist.
Replace the Power Steering Unit (PSU), also known as Power Steering Control Module (PSCM), in a S80/V70/XC70 (P3) according to VIDA Removal, replacement, and installation under 6 Suspension and steering > 64 Steering > 645 power steering equipment > Actuator speed dependent servo assistance.
On XC90s and S60s, there is no replacement procedure in VIDA, so the location is shown in this document. Once the driver's kick panel is removed, the PSU is visible.
In the VIDA parts catalog, the PSU for S80/V70/XC70 (P3) can be found under 6 Suspension and steering > 64 Steering > 642 steering gear > Steering box ECPS.
In the VIDA parts catalog, the PSU for XC90/S60 (P2) can be found under 6 Suspension and steering > 64 Steering > Steering box LHD ECPS Speed-related power steering, LHD.
The way you verify you have speed sensitive steering is to look at the steering rack. If it has an electrical connector plugged in your vehicle has these feature. Whenever a fuse for the module blows or the module acts up the steering is almost inpossible to turn. Good luck to you and hope these information helps you out :)
Wednesday, August 8th, 2012 AT 6:57 PM