Both front windows of my 54 reg megane have stopped working and Renault dealers have a backlog of the regulators/motors on order due to supply difficulties from Japan.
As I'm unable to get them replaced before an upcoming long driving holiday touring the continent, my local garage showed me how to get the door panel off (Haynes manual failed miserably) and I've established that the motors work but the control modules appear to be dead.
I've rigged up a simple circuit with switches from Maplin Electronics and a few other bits that worked on a test bench and are now installed in the car. It was quite a simple job for this poor OAP who grew up with model railways in the 1960s.
Basically it's a Double Pole Double Throw switch with centre off position connected in series with a pushbutton non-locking switch with suitable cable to two tiny spade terminals on the motor. Power is supplied to the switch(es) by using Scotchlock connectors to get it from the lead that normally plugs into the electronic control module attached to the motor. The switches are mounted in a small box which I’ve temporarily pushed into the compartment with lids in the doors.
DPDT switches are normally used for reversing direction of travel of 12 volt model railways.
This switch is different in having a centre off position and only applying voltage whilst in either on position.
Putting the push-and-hold for ‘on’ switch in series means that it is easier to let go of the button when the window reaches the required position than just relying on switching the DPDT switch to its ‘off’ position and when that switch is in the centre off position there is an extra safety factor preventing accidental movement of the window.
This is important because a locking-on switch would strip the gears when the window reaches top or bottom and the motor continued to turn, or burn out the motor.
There is a danger with my arrangement that someone’s fingers could get trapped when the window goes up so it might not pass Health and Safety rules. The electronic module senses the extra load and cuts off the supply when the window gets to top or bottom or there is an obstruction.
It should do the job on a temporary basis until my return in july when I may try to get something a bit more sophisticated made up. The parts used so far should cost less than £20 per window. Anyone with basic soldering skills will be able to do the same and those who cannot solder could use Lucar spade connectors instead.
I'm not brilliant with electronics, having given up when simple transistor circuits were replaced by unnecessarily complicated integrated circuits, but I might be able to research enough to provide the current sensing that will, with relays, cut off the voltage to the motor when it meets an unusual resistance like top or bottom or fingers. Using relays should also enable the original switches to be used and the whole gubbins hidden within the door, though it would add to the cost.
Possibly with the hints I've given someone else with more experience of electronic circuits could also have a go and provide a suitable circuit that any electronics amateur could build. I would hope that a kit of parts should cost well under £50 with a ready built one not costing much more than £20 extra if a hobbyist can be found to undertake the assembly in his spare time.
If there is interest I'll take some pictures of my assembly while I’m installing it, though I’m not sure how to upload them to the site someone else put pictures on for us to see.
I’ve created an email address ‘meganewindowathotmail.co.uk’ if anyone wants to contact me or wants me to email pictures I've taken while doing the job to them (time permitting).
KW
June 2011
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