E53 servotronic issue

[Kostgeor]

Hello everyone!
I need some help to diagnose an issue regarding servotronic system on my bmw e53 2000 model. The issue is: when I start the car, intermittently, the steering will be heavy (No servotronic assistance available.) If I turn the ignition off and on again, everything works fine. I have double checked that the solenoid is working fine. In the GMIII (INPA), there is one fault code, which says that the speed signal going from ABS to GMIII has been interrupted. I have already checked with 3 used GMIII's, with the same result.
Have you ever experienced anything similar before? I am running out of ideas.
Thanks a lot for your time,
Kostgeor

[HomeMechanic]

To me it sounds like a power steering pump issue.
Have you checked the transceiver of the power steering?
Here is a nice you tube video that can help
Bmw Eps diagnose and repair (No Flexray communication) - YouTube

[Kostgeor]

Hello and thanks for the reply. However my car doesn't have electric power steering, it has a hydraulic steering system and pump. My issue is, that the body module zke detects an intermittent loss of the speed signal. This deactivates the servotronic system for safety reasons. My question is, is the zke that has gone bad or it is the abs/dsc module that generates the speed signal bad? I have no errors on abs/dsc module, only one error in zke regarding this issue. Thanks for any help!
Kostgeor.