One side of the diodes (Cathode) connects direct to the battery, that's why a shorted diode can drain the battery. Ign switch is not in the circuit.

https://www.startekinfo.com/StarTek/outside/12265/disc_2/program/ETM/82_300.pdf

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85 300D turbo pristine w 157k when purchased 167,870 July 2025
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked