Servotronic

[Jimmy90]

Morning all.

I have suspicion that my servotronic is to fault for my steering issues. I'm trying to find a replacement but without success.

Can these be repaired? What would be the implications of fitting another with a different part number.

My steering has always been heavy since I brought the car. Having never driven another I had nothing to compare it to. For all I know the last owner may have fitted the wrong part number relay?

I'm still waiting on Volvo coming back to me on if the can get one. Any advice greatly appreciated.

My part no for the one fitted is 31280723
I've a 2010 (10) redesign.

Cheers

[Moose Test]

In your previous post on this subject, you mentioned that there was a physical 'click' in the rack when you turned it. That cannot be down to the servotronic control unit and hence as I said at that time, I'd consider that it's the rack at fault.

Subjective but in my case (heavy steering but not discernable 'stepping', play or non-linearity) it was also the rack at fault.

It is possible to test the servotronic unit's function - I describe it in this post https://www.volvoforums.org.uk/showthread.php?t=283335. Essentially it's a digitally controlled constant current source. The faster the car is travelling, the less current it applies to the hydraulic control valve on the rack, and hence the less mechanical assist is given. You test it by disconnecting the control valve from the unit and substituting it for a suitable load resistor. You can then measure the current through the load resistor as you drive the vehicle, and note whether or not it changes in proportion to road speed as expected. Even if the control unit itself behaves correctly, that's not to say that the control valve it drives on the rack doesn't have problems and isn't responding to the control signal properly.

You could try just swapping the servotronic unit for a used part. In answer to your question, the "worst" thing that could happen is that is simply won't work at all due to software/firmware incompatibility with the rest of the car's systems. If you do, and it doesn't (i.e. the steering becomes even heavier) at least you'd know it's very likely that the original is working correctly, I guess.