[V8] '93 V8Q - Speed sensitive power assisted steering

[Paul Jager]

ZF (servotronic et al) supplies a bevy of manufacturers, same stuff. So the 
Volvo rack would be of similar spec to others. The older racks (90's) will 
be different as there is a Servotronic II out there. Not sure the year that 
was introduced.

I read somewhere about the pulse but that is incorrect ZF manual - page 11 
ZF Lenksysteme states current (max at low speed, min at high speed) which 
makes more sense for a control valve. (Although some cheap idle air 
actuators are pulsed on/off).

-----Original Message----- 
From: dsaad at icehouse.net
Sent: Monday, March 12, 2012 9:52 AM
To: v8 at audifans.com
Subject: Re: [V8] '93 V8Q - Speed sensitive power assisted steering

Not sure about how the volvo works, but the Audi servotronic has a
two-wire solenoid looking thing on the pinion shaft controlled by a
control unit mounted under the steering column.  If you have a break in
the wiring (meaning an open circuit somewhere) the system goes into
minimum assist.  The solenoid is not pulsed - it works by varying the
current through the coil.  There is a guy named Roger at Jorgen Automotive
(the steering rack rebuilders) who can explain how to test it in great
detail.  Bottom line though is I bet you have a wiring problem. This is an
Audi after all.  Since I JUST WENT THROUGH THIS (I am yelling because I
know my car reads this list), be aware there is a way you can be fooled by
a simple ohm meter test.  It happened to me.  The best way to test for an
open is from the connector at the control unit.  Measure the resistance
across the coil from there and you should get 7 ohms I think.  Where I got
hosed was the resistance tested fine, but the connection was bad and it
could not carry the current.  It turned out the connector pin got bent and
the plastic connector parts broke on installation of the rack.  It worked
intermittently.  If you inject a voltage on these pins you can test the
assist levels for different voltages.  Don't hook it to 12 volts though!
you need a current limited variable power supply or else you may burn up
the solenoid thingy.



Dave


> Has anyone had issues with the power assisted steering? Specifically it
> appears as though the assist has dropped dramatically at parking speeds.
> The
> assist is still there but the level is as though I'm at highway speeds. I
> do
> not see in the manual anything about this.
>
>
>
> Assistance?......
>
>
>
> Thanks
>
> Allan
>
> '93 Audi V8 Q
>
> '91 Suzuki Samurai 4x4
>
> '90 VW Corrado G60
>
> '81 Truimph TR8
>
> '73 Mercedes Benz 450 SEL
>
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