Illuminated Rear Heated Window Switch

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For some reason BMW didn't fit all E30s with an illuminated demist switch.

This is a simple to follow guide, to covert your demister switch into an illuminated one.

The guide comes in two parts. The in-car procedure, and modifying the demist switch.

Tools and Parts

  • A spare hazard warning switch.
  • Two lengths of wire with connectors attached (one 20cm and the other 5cm). Connector PN. 61 13 1 358 924
  • Stanley knife blade.
  • Wire cutters.
  • Electrical tape.
  • Small flat screwdriver.
  • Soldering iron.


1.) Remove the blanking plate next to the demist switch with a combination of the Stanley knife blade and the screwdriver. Don't try and use only the screwdriver on the switches, as this can result in damage to the dash.


2.) you will then be able to extract the demist and hazard switches by inserting your index finger and pulling them towards you. Once you have extracted the switches from the dash, you can unplug them.


3.) Use the screwdriver to unclip the plastic cover from the front of the demist switch plug. Some plugs have a white plastic peg in the top left pin hole. You will need to extract the white peg (if fitted)


4.) Take the 20cm piece of wire and plug the connector end into the hole marked number 7.


5.) Loop the wire through the two switch holes in the dash.


6.) Take the hazard warning plug and strip away a small piece of insulation from the grey/red wire (pin 7) then solder the 20cm piece of wire to it. Wrap the joint with electrical tape. You can now plug in the hazard switch and insert it back into the dash.


7.) Now going back to the demist plug, strip away a small piece of insulation from the brown wire (pin 6) then solder the 5cm piece of wire to it. Insulate the joint using some electrical tape.


8.) Then plug the connector end into the hole marked number 8.


9.) You can now re-fit the plastic cover to the front of the plug.


This concludes the in-car part of the procedure.



  • A spare hazard warning switch.
  • A 75 ohm carbon resistor.
  • Two small flat screwdrivers.
  • Soldering iron.

1.) There are two different types of hazard warning switch fitted to the E30. One can be used as a sacrificial switch, while the other can't. You will need the first of the two types (with the diode/resistor visible on the bottom).


2.) Remove the cover of the hazard switch by inserting the screwdrivers into each of the plastic tabs on the side if the switch.


3.) The switch may well fall to pieces but it is simple to put it back together.


4.) Remove the cover from the top of the switch.


5.) Use exactly the same procedure on your demist switch and you will be left with the demist cover. Discard the rest of the old demist switch as it is now useless. Attach the demist cover to the front of the hazard switch.


6.) Now to get the correct illumination on the switch, you will need to replace the 150 ohm resistor with a 75 ohm one.


7.) You do this by unsoldering the resistor from the centre of the inside of the switch.


8.) and the diode from the pin on the rear.


9.) Then solder in the new resistor and diode.


Then re-assemble the switch and fit it into the dashboard.

LEGAL DISCLAIMER: I am not responsible for any problems that may arise following this procedure. Any work you do is at your own risk.