Microswitch Replacement - How To

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  Z3 roadster 2.8
Location: Telford

Microswitch Replacement - How To

Post by g8jka » Sat 28 Apr, 2012 14:44

After having intermittent problems with the electric roof on my zed and identifying the problem to be a faulty microswitch, I decided I would finally cure the problem and replace the switch. It is a fairly simple job but does require a little modification from the old switch to the new switch.

Here is how I did it:

Firstly you need to purchase a new microswitch to replace the old one. I got a miniature microswitch with lever from Maplins for the cost of £2.49.

Next step is to remove the casing that houses the current microswitch situated in the middle of the roof just above the passenger window. To do this it is easier to lift the roof a little so that the housing is in full view. To remove the screws a T25 torx tool needs to be used.

This is what we need to remove

All removed

Rear view showing the switch itself that needs to come out

Now remove the wires leading to the switch and pop out the actual switch itself and put the casing somewhere safe

Cut off the two wires leaving you with just the microswitch. Below shows the old switch removed and the new switch that needs to be fitted

As we can see there is a difference between the two switches, the main one being the lever which is longer and has a U shaped bend at the end of it. This is where we need to modify the switches as the lever on the new switch is not long enough to reach outside of the casing and to touch against the roof when it closes, deactivating the switch and circuit

I cut the lever off the old switch and glued it into place onto the new microswitch lever, leaving me with a new switch and a lever long enough to press against the hood and working the microswitch as it should

Only two of the terminals are needed to make the microswitch work so I removed the middle one to allow a little better access for the wires when they are put back into the housing

Now back to the car where we need to extend the wires that will connect to the switch. As the terminals are separate on the new switch the wires are not long enough to reach both of them. The plastic now needs to be pulls back to give a bit more access to the wires so they can be extended a little. I added a little bit of wire onto each of the wires coming upto the switch by soldering them and finishing with heat shrink so that it is nice and neat and finally added two small spade terminals to the end of each extended wire. I also put some heatshrink over the end of the plastic after pulling it back to protect the wires

The switch can now be put back into the housing with the wires connected and can now be tested to make sure it works.The roof should go up and down with the lever in its normal position and should not go up and down if the lever is depressed so that the switch clicks and closes the circuit (as if the roof was closed)

Hopefully if all is working correctly the housing can be put back and secured with the torx bolts removed earlier

Carefully close the roof keeping you eye on the lever making sure it contacts the roof, pressing it down so that it clicks the microswitch and shuts off the circuit so that the roof will not open with the roof closed. Then open up the roof as per usual lifting it into position so that the lever no longer contacts the roof, creating the switch circuit and allowing the roof to be opened as normal with the roof switch and brake pedal. Some adjustments may need to be made to the lever to make sure it contacts the roof, if it is to short it won't contact the roof and press the switch meaning the circuit is always made and the roof motor will work all the time even with the roof locked into position if the button and brake pedal are used as usual. If it is too long it may just snap off the lever of the new microswitch, again making the circuit all the time meaning the roof will work in all positions if the button and pedal are pressed.

If all goes to plan, you should now have a working microswitch and a fully functioning roof :)
2000 BMW Z3 2.8 Titanium Silver Roadster with too many mods to list :-D :drive
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Brian H
Joined: Tue 16 Dec, 2008 19:55
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  Z3 roadster 3.0i

Re: Microswitch Replacement - How To

Post by Brian H » Sat 28 Apr, 2012 16:17

Great write up, well worth the effort as the OEM microswitch at coopers BMW costs £63.00.


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Joined: Thu 26 Feb, 2009 14:07
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  Z3 roadster 2.8
Location: milton keynes

Re: Microswitch Replacement - How To

Post by peterandjenny » Fri 14 Sep, 2012 16:45

Just done this , works well :-) :)

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  M roadster S54
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Re: Microswitch Replacement - How To

Post by Gazza » Fri 14 Sep, 2012 16:55

Moved to the Z3 Knowledge Base :wink:

"Understeer is when you hit the wall with the front of the car, oversteer is when you hit the wall with the rear of the car. Horsepower is how fast you hit the wall and torque is how far you take the wall with you"

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