BMW E30 Cabriolet Best Mod Ever

BMW E30 Cabriolet Window Drop Module


I've finally got to the stage of a "Production" version of my WDM for the E30 Cabriolet.
The design is now more sophisticated in some ways, but remains simple and as un-invasive as possible. I did not want to start drilling holes, adding sensors and micro switches, or modifying the car in any way, the aim was to use existing sensory circuits, with as little wiring alteration as possible, meaning that the unit could be removed at any time with the least hassle, or transferred to another E30 Cabriolet if needed.

What the WDM does not achieve:

  Due to sensor limitations the Windows drop shortly AFTER either the passenger or driver door is opened. I deemed this acceptable as there is no wear or force applied to the inner edge of the roof cloth as the door swings open. Damage or snagging occurs on door closure.

The windows do not remain down until the doors are closed, but cycle through an up down
loop controlled by a timer, until the doors are closed, not a perfect solution, but in practice it is not an issue.

What the WDM does achieve:

Saves your new roof from damage or stops your existing roof from further damage, allows your windows to be set up to close fully into the rubber seals.

The unit does not affect the normal window operation by the driver or passenger using  the regular up/down controls under any conditions.

The entire system resides inside the handbrake center console, is invisible, and requires no drilling, or physical modification to the vehicle apart from wiring splices and cable running.

The system senses when there is no vehicle activity and switches the WDM off. This occurs two minutes after the car is "dormant" and sets current drain to zero.

When the Cabriolet roof is stowed, the system shuts down leaving normal window control for the driver or passenger as required.

As the WDM operates on a timer basis, the windows remain slightly lowered for 20 seconds before they automatically close. This period can be increased by the user. If one or both of the doors remains open for longer than the "wait" period, the windows simply raise and drop again, beginning another cycle until the doors are closed, at which point the windows will remain closed.

Installation requires 5 wiring splices into existing cables in the car, and 4 cables need to be cut and extended (These are earth cables from the two front window switches ).

The WDM consists or two circuit boards, one Controller Board and one Power Management Board, assuming your BMW has no switches in the Hand Brake Console, this is where the two boards are fitted and wired to the various control points making installation quite simple.

Both circuit boards are fitted their own fuses to protect the system, you and the car.

25 amp cable and connectors have been used to easily handle the window motor "stall"
currents which are quite high.

The ability to turn off the system without lowering the roof or pulling a fuse would seem necessary, for example when working on the vehicle or cleaning/detailing etc. I did not want to add a cumbersome switch or make holes for such so have added a proximity switch which lives under the rear ashtray. Pulling  the ashtray turns off the system, simple and invisible.