DIY: Exterior / Side / Door Mirror Control Switch Repair

E28 technical advice asked and given! Troubleshooting, modifications and more.
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thesalboy
Posts: 36
Joined: Jan 13, 2009 11:33 AM
Location: Los Angeles, CA

DIY: Exterior / Side / Door Mirror Control Switch Repair

Post by thesalboy »

Neither of my exterior mirrors would budge. When operating the control switch, in certain directions, the mirror motors would make a clicking sound, but would not move. Fiddling with the switch would get them to click in all directions except down. Given that fiddling changed things, and since both mirrors made the clicks together, I decided it had to be the switch. So I pulled it out.

As with everything interior, patience is the key. The switch can be pried out, removed, and disconnected without removing the door panel. The first thing I noticed is that I was not the first person to remove the switch, and that one of the people who had done so before me did not honor the key. An entire corner of the cover was broken off. I very carefully pulled the switch apart.

I'd read on this forum about little spring loaded balls flying out on disassembly. Turns out they are ball pairs - they look like little dumbbells. They are seated in springs to force them to contact a copper trace board. My switch had been reassembled with grease, so everything stayed put. However, the grease had hardened and - I suspected - was preventing sufficient current from passing to operate the mirror motors. The white rod serves as the pivot point for the joystick controller.

Image

I realized the driver/passenger selector also had a ball pair, so I carefully disassembled that too. Same grease problem.

Image

I cleaned the copper traces with a pencil eraser (I read a post on this board about that - great tip!). You can see three contact points, and how one of them is heat scored. Presumably this is the trace that carries the mirror heater current, and this explains why BMW changed this design. (Strangely, my '86 E30 has separate mirror heater wires). I soaked the ball pairs in lacquer thinner to remove the grease, then rubbed them on scotchbrite to remove tarnish.

Image

I reassembled everything using Super Lube to hold the ball pairs and joystick to their springs and to lubricate contact points, but I didn't go overboard as the last person did.

Image

Once back together, I used scotch tape on the broken corner - it didn't need much as the other three tabs did most of the holding-together work.

Image

I hooked it back up and at first the mirror motors still just clicked, but then it started working. Both mirrors work in all directions now. I was multitasking, but together this took me all of a half hour.
John in VA
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Location: Leesburg, VA

Post by John in VA »

Nice work & write-up!
Brad D.
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Beamter
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Post by Brad D. »

Great writeup!
thesalboy
Posts: 36
Joined: Jan 13, 2009 11:33 AM
Location: Los Angeles, CA

Post by thesalboy »

Thanks! My second fix to my new (to me) 1-owner, 300K+ mile, $500 E28. :banana: The first one involved a small piece of coat hanger. Gotta love these boards.
1st 5er
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Post by 1st 5er »

Oh yeah, gotta love it, MyE28.com.
wkohler
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Post by wkohler »

Damn. I never once would have thought of rebuilding the switch. I just throw 'em out and replace them! :laugh:

Well, that gives me something to do other than telling kids to get off my lawn.
hodgepodge
Posts: 48
Joined: Aug 29, 2018 9:18 PM
Location: 15317

Re: DIY: Exterior / Side / Door Mirror Control Switch Repair

Post by hodgepodge »

Thanks for this info. I just pulled the switch out of my M5 project car, pulled it apart and cleaned it up. Before cleaning, the driver's side was spotty and the passengers side just clicked. The circuiit board contact points were covered in white powder. After I cleaned it up, driver's side works great but, as I suspected, the passenger side mirror is shot and does not respond to the in-out command. I have several spare mirrors and will pull the door card to test them before installing a replacement. Thanks for the great write up! I also would have just replaced the unit (for $50+) and was looking for one when your "exploded" image showed up. Thanks!
bogdaneise
Posts: 16
Joined: Nov 19, 2021 4:51 PM
Location: 33160

Re: DIY: Exterior / Side / Door Mirror Control Switch Repair

Post by bogdaneise »

Hello,
Any DYI on how to take out the switch without taking the door panel out? Thank you!
thesalboy
Posts: 36
Joined: Jan 13, 2009 11:33 AM
Location: Los Angeles, CA

Re: DIY: Exterior / Side / Door Mirror Control Switch Repair

Post by thesalboy »

Well it's been 12 years, and I no longer have the car, but pretty sure you just pry it out, taking care to understand how the base of the unit is longer on one end.
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