<E30> Make power windows & sunroof work with ignition off

[Michiel van Wessem <jmvw@xxxxxxxxx>]

Hi people,

I made a very simple modification to my car today that allows me to operate
the power windows and sunroof regardless of the position of the ignition
switch.

It always bothered me that with the ignition off, the windows and sunroof
wouldn't work. At gas stations, I had to have the ignition key in the run
position to lower the window to say "fillup with regular, please" and then
raise the window again to keep the cold out. Also, I now suspect that
filling up the tank with the ignition on throws off the OBC's idea of how
much fuel is in the tank, similar to how that apparently messes up the fuel
gauge of our friends with newer bimmers - but that's a another story.

Well, so I looked up the schematic for the power windows in the Bentley
manual and I saw that power to the windows comes from "load reduction relay
K5". This relay supplies power to the windows only when the ignition key is
in the run position. I suspect this is done so that:

1. If you leave kids in the car, they won't play with the windows draining
the battery and possibly throwing each other out the window.
2. You won't play with the windows draining the battery. I think you'd
really have to keep lowering and raising them for a quite a while to do this.
3. Maybe so the windows can't be operated while the starter is being used,
which might cause too great a drain on the battery and will weaken the
power available to starter. 

In my case, these things don't apply and it's a PITA that the ignition
needs to be on. So I shorted Pin 87 and 30 on relay K5 and now the windows
and moonroof will always operate, even when the ignition key is out.

Relay K5 is in the main fuse box. In my car, the plastic cover indicates
which relay is K5. 

I used a length of bare copper wire (you could strip a piece of telephone
wire) and wrapped it two times around pin 87 and 30 on the relay and I put
the relay back in. Nicer would be to make a jumper wire with connectors on
the end and plug it in to the relay sockets. Then you can keep the relay as
a spare part. Or you could gut an old relay and solder in the wire
connection. 

I measured a draw on the battery even when the windows or sunroof aren't
operated. It was about 154 mA. That's from the lamps in the switches. To
avoid having to run extra wires from a lighting circuit, they powered the
lamps from the voltage over the switches. I don't think these lights
draining the battery will be a problem. I don't know what the rating of our
batteries is, but I think it's more then 70 Ah. That means that these
lights will take more then 18 days to drain the battery. There's something
else though: being on all the time, these lamps will burn out sooner then
otherwise. Replacing them with LED's would fix this and removing them would
too. According to the Bentley manual cars made before late 1986 do not have
lights in the switches. 

I like things better this way. 

Hope this hasn't been covered before. Disclaimer: forget about sueing me
when you blow up your car. Whatever you do, it's your responsibility.

Now go have fun,

Michiel
Ps: another planned modification is to put a timer in the sunroof switch so
that it always opens or closes all the way if you hit the switch. 

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