Help, I have been enjoying my 1997 XK8 convertible even in the heat of the past weeks. But noted that the PS fluid was low so I topped it up. Was okay for a day or so and then started to experience hard steering at mostly slower speeds and parking. Made appointment for a front end alignment and Firestone service rep suggested jacking it up and turning wheels lock to lock a number of times as he thought I may have gotten air in the system. That seemed to work and I thanked him for the suggestion when car was in for alignment. But two days later it really got bad and nothing has helped. Checked #12 fuse on driver side fascia fuse box (okay), fluid level and did the air bleed trick again. Suspect a problem with the VSM (Servo Relay)(PS control module) (or whatever it is officially called and hidden behind/beside glove box) or the PS Servo located on the rack. I understand how the system works, so it is obvious I am not getting assistance at low vehicle speeds. Car is drivable but tough parking or in slow speed turns. Is there any easy and/or recommended way to test/diagnosis what the problem is? I plan to get under the car and see if the PS Servo on the rack reads 4ohms, but that seems to be the only test I have found. Help, would like to get this fix for this weekend. Also if the PS Servo on the rack is removed does PS fluid leak/drain out?

 

Hi Michael

I have a bit of experience with the Servotronic control module and would be happy to run a diagnostics on that for you. However you're in the US and i'm in Denmark Europe so getting it around before the weekend is going to be hard

I did a quick check on ebay and there's a bunch of Audi modules available at less than 20 USD (i doubt we can send your original back and forth for that kind of money) so getting one of those could be a way to verify if your control module is at fault.

Having said that i haven't really heard of any breaking previously so it's not a likely culprit.

I don't have any experience with the actual steering rack so i can't help you on that one.

Happy hunting.

Best
/Stig.

 

Stig, I am getting under the car today and will check the ohms on the Servo at the steering rack. It may also be the typical loose/dirty connection so that is another check to be done underneath. After that, at $20, I will get an Audi SCM and try that. Thanks for your input!

 

Well I got under the car this afternoon and found no broken or damaged wires to the Servo on the Steering rack. However my hands are too big to allow access to the electrical connectors on either end of the wiring harness clipped to the rack. So I put the car back down (At least got a chance to check brake pads, etc.) and started to look at the glovebox for access to the SCM relay. Ran out of time as that appears to be simple to get at but time consuming! Had dinner and then went for a ride with the top down (always), hard steering at slow speeds, 65F and some good music as it was really pleasant clear evening with a bright moon.
I have a ZF Servotronic SCM on its way to me for $9! I will try it and see if that changes the low speed steering effort or it will be a spare for a later date. Do want to get this working right as I'm concerned about mechanical damage to steering column and rack due to having to really muscle through any low speed turning. (Parking lot maneuvers in particular!)

 

Good to hear that you are working the problem and at 9$ for a spare SCM it's a no brainer.

Regarding mechanical damage caused by unassisted steering i know that a few people have simply removed the SCM completely and i haven't heard of any problems as a result.
Personally i drove around without the SCM for a good four months with no adverse effect. Beyond slightly bigger over arms that is So i wouldn't worry about it too much.
(i personally never understood how Jaguar decided it was a good idea to use that level of over assistance on the steering which is why i pulled it in the first place)

One last think to note. The SCM's from Audi, BMW and Ferrari are slightly different. They should fit and function perfectly well but the level of assistance they provide at different speed vary between make and model. (One thing among quite a few ZF aren't really advertising)

Best
/Stig.