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Date: Sat, 27 Dec 1997 11:44:30 +0800
From: Tee Mai Wah <> To:
Subject: power window

Here's an attachment where you could put up on your page. It's a wiring diagram for the power windows to work when you open your doors, even if your ignition is off! It's actually a standard feature of the e30 that I found out just thought of sharing the knowledge with all enthuthiast out there


Power window relay circuit for E30.

          85             87 
          _at_              _at_ 1                                      
          _at_                1           
      [---#----]     \     1
      [        ]========== 1
      [---#----]     /     1
          _at_                1 
          _at_                _at_    
          86              30

SPST Relay

30 - positive constant(not form ignition,direct battery) 85 - input from door contact
86 - positive constant(shared with pole 30) 87 - output to circuit breaker input

Relay type 12/14 volts 30A rating.


  1. Ground signal from door contact will complete circuit of the transformer creating a magnet.Magnet will then pull contact from 30 to 87.Now windows will have power to roll up/down when the doors are open.
  2. Check wiring of your car, you may have this feature but may not be working.
  3. Check all wiring conform to their respective polarity.
  4. Hook up contact 87 to the input of the circuit breaker, this is to prevent the window circuit from overloading.

Use this info as a guide only, if in doubt have circuit checked with a qualified electrician or technician.I hold no responsibilities over any faults incurred by any parties.

Any quiries please email (detailed installed info available)

My power windows also utilises a one touch roll up and down.No more holding the switches down.
Word of advice:try to avoid rolling windows together it might cause an overload of current.

*This project can be carried in cars that is negative grounded and with a reverse polarity power window circuit.

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