The power steering system has a variable voltage signal. Without the signal, the steering is heavy for high speed autobahn driving. With the signal, the power assist is high for parking. It appears that the servotronic is designed so that if it fails you can connect the wired plugs to each other to recover maximum steering assist to get you home.

• George Mann used an 18 ohm fixed resistor (wire wound high capacity type) to bypass his servotronic -- 18 ohms gave him reasonable balance between highway and city driving feel.

As always to be complete, possible failure points to check
speed signal is NG
plugs/wiring to/from servtronic are NG
- Servotronic regulator unit is NG
fix is here

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Servotronic unit on steering box is NG
Generally this is because the small filter screen becomes clogged.
The key symptom is that the loss of power assist is intermittent.
fix is here

Steering box itself is NG -- more detail later

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