Servotronic

Servotronic







The electronics of the Servotronic control have been integrated into the General Module.

The system continues to vary the amount of steering assist based upon road speed, however, some modifications to the control logic have been incorporated. For the Servotronic control operation, the GM III receives the following signals:
- KI. R directly from the ignition switch.
- Speed signal 'A" directly from the IKE.
- Vehicle Speed signal from the IKE over the K-Bus (plausibility checking).

Control Logics







When KL R is switched "on", the Servotronic control is active and a check for KI 15 is made from the IKE. If KI 15 is present, the Servotronic remains active. If the General Module receives the signal KI 15 "off", the Servotronic is switched off. If no KL 15 "Off" response is received from the IKE, the Servotronic control remains active.

The switch "on" of the Servotronic with KI R ensures that no delay is encountered when the engine is started and the vehicle is immediately driven. The electro-hydraulic solenoid is pulse width modulated for control. The amount of Servotronic assist is inversely proportional to the road speed. As road speed increases, the assist will decrease with maximum assist at idle for parking maneuvers.

The Servotronic control recognizes acceleration and braking from the difference between the two speed signals. The signal from the IKE is received and updated every two seconds. The servo assist is reduced evenly during acceleration for smooth steering response. To ensure the necessary assist for lower speeds, the assist is adopted to the lower direct reading during decel or braking.

The fault logics for a total failure of speed signal "A" are as follows:
- A failure when starting or at low road speeds will adopt the full assist mode.
- If a fault occurs while driving at higher speed, the minimum assist value is adopted.

Both of these conditions are retained until the fault is repaired and the ignition switch has been cycled. The Servotronic control is now diagnosible through the fault memory of the GM III.