Design: Opening a BMW 8 Series Trunk

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When the BMW 8-series debuted in 1989, it was one of the most technologically advanced cars at the time, designed through CAD, and having a drag coefficient of just 0.29 (same coefficient as the 2000 Prius -- now if they can make a Prius look like an 8 series, I'm sold). The 850i featured the first six speed manual transmission mated with a V12 engine, integrated pop-up headlights, and pioneered numerous engineering enhancements that became standard for later BMWs such as drive-by-wire and using a Local Area Network as an automotive application. Power windows that automatically roll up in excess of 70mph, power seats, power sunroof, power trunk. The 8 series is known for having electrical problems -- I have to say that aside from needing to replace my batteries every year (resulting more from my winter storage than any fault of BMW's) I haven't noticed any problems.
With 300 horsepower and 362 lb-ft of torque, it's still powerful by today's standards, and everytime I take it out for a drive, I have to remind myself that 60mph is only 6 seconds away, and that without very much effort at all I could be at 110, and not even feel like I'm going faster than 70.
Running a V12 engine along with all the electrics in this car requires not just one, but two car batteries. Every year around this time (because the registration notice for this vehicle arrives) I get into the car, put the key into the ignition, turn the switch, and instead of hearing the soft purring of a 12-cylinder engine, I hear silence. The batteries are completely devoid of charge, and I'll need to recharge the batteries before the 8 can thunder off onto the highway. Of course, having a dead battery presents a problem, as the car normally uses the LAN to signal to the trunk that the doors are unlocked, and that the trunk should open if the doors are unlocked. Without power, you can press on the latch all day, and it won't open ever. Every year, I forget about how I go about solving this problem. The first time the batteries died, I used the other car and jumper cables to supply enough power for the doors. This year, because of how I had parked the cars, this wasn't an option to me.
Instead, I turned to the low-tech solution: the car key. It seems that next to the trunk latch on the underside is keyhole. The directions for opening the trunk get complicated here, and I'm not sure why they didn't just have the standard turn the key, trunk is unlocked method, as the procedure is as follows:


  1. Insert Key.
  2. Push Key up into the keyhole.
  3. Turn Key Counter-Clockwise
  4. Stop Pressing Up and Return Key to Normal Position.
  5. Remove Key from Keyhole.
  6. Push Keyhole Up.
  7. Trunk is now unlocked.

It's the most ridiculous, non-intuitive method of opening a trunk I've ever experienced.




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2 Comments

I have a BMW 850i (1991). I had some electrical issues (leakage of electrical current), unhooked the batteries, took out the 6 relays in the trunk. Someone slammed the trunk shut and now I can't get in to put back the relays. Apparently, the manual system doesn't work either (something wrong with the keyhole mechanism). Is there another way to get in or do I have to break it open as a last resort?

Hi, Gino, I'm not an electrical expert, but there's a electrical pole under the hood of the trunk to allow for jumpstarts. If you hook a battery there via jumper cables, that might give you enough power to use the electronic locks.

I'm not sure what relays were removed, so use at your own risk.

The manual way feels broken ( think it is broken every time I try and use it, but it does actually work). Just follow my step by step instructions -- the pushing in of the key to open is the hardest part, and the design of the key doesn't help, but it should work.

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