Let's go to school...
The rectangular plug with 3 pins are for power, ground, and keyed power.
The round plug is for the signals. One is for the trunk, one is for the passenger's handle, one is for the driver's handle.
If you unlock or lock the doors, the signal jumps from power (unlocked) to ground (locked)... Get it??
We sell the CD that has the diagrams if needed...Partsshop.
1992 500E (very soon I hope
1981 280GE SWB
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