The BMW Repair Guide used this 2005 Z4 for the following article.
The following article gives detailed instructions on performing a convertible microswitch replacement on a BMW E85 Z4 series car. Even though we have used a 2007 BMW Z4 2.5i to perform this installation, this article can be applied to any E85 Z4 series vehicle produced from 2002-2008.
If the convertible top on your BMW Z4 no longer functions and you are receiving a yellow light on the control switch, then you may have a faulty microswitch. The BMW Z4 convertible microswitch is a simple fix that will get your top working again in short time.
There is nothing worse than wanting to put the top down on your Z4 on a sunny day and the convertible’s control switch doesn’t work. Scratch that. Actually nothing is worse than trying to put the top up in inclement weather and the convertible’s control switch doesn’t work. Whatever situation you find yourself in, the first place to start looking for an answer is in the trunk of your car.
The BMW E85 convertible microswitch is located on the back wall of your trunk within a plastic structure called the center mount. The microswitch is a “fail safe” mechanism that immobilizes your convertible top if the stowage base (storage shelf) in the trunk is in the “up” position. In other words, the trunk stowage shelf must be lowered in the trunk before you can raise or lower the top.
The BMW Z4 convertible microswitch operates in a very simple fashion; there is a tab on the back of the storage shelf that fits inside the channel of the center mount. When the shelf is lowered, the tab depresses a metal contact on the microswitch activating the convertible top. 
The most common reason for the BMW Z4 convertible microswitch malfunction is that the small metal contact falls off; it can usually be found lying on the floor of the trunk. The good news is that it is an easy repair. If you can’t find the metal contact, or if the metal contact is still in the microswitch and the top is not working with the shelf down, then you will need to replace the whole microswitch. Once again, a very easy repair.
1. Convertible microswitch (may be required) –If you cannot find the metal contact that has fallen off, or if you have followed our repair instructions below and the convertible top still does not work, then you will need to order a new microswitch.
2. Center mount (optional) –Â Â If the plastic mount that contains your microswitch is worn or damaged, you can order one here. Freshen up the trim in your trunk with this inexpensive piece that holds the microswitch.
3. Torx screws (optional) – Missing a torx mounting screw in your center mount? Order a new one here!
- Remove the two T15 torx screws that anchor the center mount to the back wall of the trunk. Disconnect electrical connection and remove the center mount from trunk.
- The next step is to remove the microswitch from the center mount. The switch is simply clipped on to the side of the mount…use a flat blade screwdriver to pry the clip loose and remove the microswitch.
- If you were able to retrieve the small metal clip that activates the switch, we will show you how to reattach it. If you had to order a new microswitch, skip to step 5 below.
- Place the microswitch on a bench as shown. The metal clip simply snaps back on the switch as shown in the following images:
- Reinstall the BMW E85 convertible microswitch into the center mount making sure the clip is firmly seated. ***Play close attention to the direction of the metal clip as it is being installed.
- Reinstall the center mount on back wall of trunk as shown in step 1 above. Make sure the storage shelf tab is positioned inside the channel of the center mount.
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