Problem: Some if not all the thumbwheel controls aren't lighting up at night anymore. The tumbwheel controls are lit with plain old bulbs. I'm wondering why BMW didn't use LEDs for this. But I guess LEDs didn't give enough light when they designed the control panel.
An other problem could be that you are missing some of the illumination or the green selector lights of the buttons. These are lit by LEDs used in series. So if one goes out a group of three will go out.
Models: All E32 and E34 models with the IHKA climate control system.
Replacing the bulbs:
I figured it would be easier to remove the panel from the car before opening it :-) To remove the panel "the factory way" remove the cover from the rear demister switch with a small screwdriver.
Put a screwdriver into the hole you created by removing the cover.
Use the screwdriver to push in the end of the clip so it will slacken at the front. If you do this correctly the panel will pop out just like that. If you do it incorrectly or if you don't use enought pressure you will end up cursing why it won't come out. Do take your time as you don't want to break this overpriced control panel. Don't worry about the clip as it's only one or two euro from the dealer ;-)
Now remove the two or three (if you have a independant heater or ventilation system) connectors from the panel. Yes! The panel is free and you can take it into the house where it's warm (it's currently 0 degrees Celcius over here).
First remove the three pins that hold the thumbwheels. Take notice of their possition so you can easily put them back later.
Remove the connector to the temperature sensor blower motor and undo the four screws in each corner of the rear lid.
After removing the cover you get to the PCB. This is held in place by four screws. Undo these and pull the PCB out. Make sure you don't damage the microswitches for the driverside temperature and blower motor thumbwheel. You can slightly pull the thumbwheels up.
I have one of the first E32s so the buttons are not attached to the PCB. If you are just replacing the bulbs it doesn't matter. But if you are replacing one of the LEDs you do have to remove the buttons. --LINK TO JON EVANS' PICTURES--
Now get your soldering iron and tin sucker out and get to work!
Replacement is reverse of removal. Do make sure you put the pins for the thumbwheels back in properly. Before you reinstall the panel in your car check to see if they operatare over the entire scale. If you fell like they are stuck before you get to the end of the thumbwheel's scale the pin is installed incorrectly in the variable resistor.
Total amount of parts and cost (for convience: 1 Euro equals 1 US dollar):
| BMW partnr | description | price (1 piece) | used amount |
| 64 11 1 382 790 | Bulb "Rot" | 2.73 | 1 |
| 64 11 1 388 253 | Bulb "Weiss" | 2.21 | 2 |
Ridiculos prices if you ask me. Maybe I should've bought some LED and resistors.
Total amount of time: You can do this on your lunch break.
Story by Johan735.
If you would like to add any comments, remarks and/or corrections to this procedure, feel free to email Mike Oswald and we'll put it on our site. Share your experiences with us so others may benefit from it.