2002 745i trunk does stay up - 1994 BMW 7 Series

Is the boot light staying on? If it is then the switch is faulty!

You have two shock like openers for the trunk lid. \one on each side. They loose their ability to hold open the trunk over time. U can buy them at most auto parts stores like Auto Zone.

There are rods that hold open the trunk they look like a small piston. They get weak over time and will not hold open trunk lid. You can buy them at any auto parts store. Hope this helps

Probably the two hydraulic supports.

The switch is located in the latch of the trunk, make sure the wire connector to the switch is not pulled loose or otherwise damaged.

undo the trunk release latch to see if trunk stays shut. if it does then check for stuck release button or short to ground on that circuit.

I have a 2008 chrysler300 and i had installed a system in it and noticed that my trunk kept popping open and i doubt its the subs because i only have 1 10 inch sub and when im driving it randomly pops open and i dont know what the problem is, can anybody help with this situation?

Please make sure your keys are not in the trunk because there is a safety mechanism that will not allow the trunk to stay closed if the keys are detected in the trunk. The other issue will be if the hold down mechanism is not pulling the trunk completely closed once the trunk engages the lock. You will then have to have it serviced to make sure the pull down motor is operating.

All gas charged supports are not created equal. I recommend using O.E. for this application.
Snow,ice and trapped water make the lid heavier than it should be make sure these are not the issue.

Check the trunk door lock sensor, when it is defective the lamp will stay on.

If it is not that, then it is simply a contact in the trunk light wirings.

If you cannot fix it, then remove the bulb, if the light stays on for a long time when car is parked (at least a matter of days), you can find a flat battery when you try to restart.