BMW DDE Installation Guide and Troubleshooting
- Install the DDE in the slot that it belongs in
- Take the DDE connectors in your hand and open them 100% so that they can not be in any more of an open position.
- Plug one connector in at a time and close the latches.
- Try to start the car
You can plug the connectors in with the latch mostly open and it will latch but that doesn't matter because the flip latch doesn't just "click and secure it". The latch has cams built into the pivots and if it's not 100% open when you plug it in, the cam will prevent it from going down far enough