Seat Belt Interlock Control Unit (German: Gurt-Anlass-Steuergerät),That is unfortunate. I will pull the rear 1/4 trim. What is the black box I found under the rear seat (drivers side)View attachment 227148View attachment 227149
What it does
This module is the control unit for the Seat Belt Interlock System.- Background: In the mid-1970s, Federal Motor Vehicle Safety Standards (FMVSS 208) in the US (and briefly in certain European export specifications) mandated a safety feature to prevent the engine from starting unless the front seat occupants were buckled up.
- Operation: The control box evaluates signals from weight/occupancy sensors in the seats and microswitches inside the seat belt buckles. It only allows voltage to pass to the starter solenoid (Terminal 50) if the sequence is correct (sit down first, then buckle up).
(helped by Gemini)