Help with a VW Golf power window motor

hi,

I'm playing with the power window circuit of a 1994 Volkswagen Golf III, to drive its 12v DC motor using my arduino mega.

The VW Golf high level wiring diagrams can be read here, on page 35, but I couldn't find the datasheet of both chips on the driver board (I know, useless picture, but it was the best I could get out of my cell phone)

The chips are:

  • a Microchip "FHS03 00129" "6D56G" "LLNB9610"
  • an unknown manufacturer's "9614VGC" "6 66 30" "00080"

According to what I could understand from the wiring diagram here's how I connected the 12v battery, a 5v source that mimics what the arduino would eventually supply, and the board connector:

  • Now, when I connect the battery terminals only to the wires number 1 and 15, the motor is still, as expected (needs "enable" and "direction").
  • When I let the direction wire (number 11) touch the USB port positive or negative pole, the motor is still as expected (needs "enable").
  • Then I let the hotkey wire (black/yellow, number 7) touch the 5 volts from a computer usb port with common ground with the battery (something that sounds like "I turn the key on on the car"), the motor is still as expected (needs "direction").
  • Now (it doesn't matter whether I keep the hotkey wire connected to 5v or not), if I let the direction wire touch the 5 volts positive pole the motor turns clockwise, and when I disconnect the direction wire the motor gets still, as expected.
  • If I let the direction wire touch the negative pole, the motor turns anticlockwise, as expected, but it doesn't alwasy stop when I disconnect the wire from the negative pole, sometimes it keeps running, sometimes it stops. When it keeps running, it will stop if I let the direction wire touch the 5 volts.

Now I'd like to connect an arduino pin in place of the 5 volts usb cable, to feed the voltage needed to the direction wire (I just hope the motor will reliably stop from the anticlockwise position feeding it 5 volts for a short period of time), my question is: what it's best to do to protect the arduino in this scenario ? should I be using a diod to prevent current flowing backwards from the motor on the pin wire (it might be something the chips on the board are already there for, but since I can't get their datasheets I'll never know), or should I do something else ?

thanks and best regards,

andrea

andreacuozzo:

  • If I let the direction wire touch the negative pole, the motor turns anticlockwise, as expected, but it doesn’t alwasy stop when I disconnect the wire from the negative pole, sometimes it keeps running, sometimes it stops. When it keeps running, it will stop if I let the direction wire touch the 5 volts.

On a second thought, this behaviour might be the one-push-to-fully-close-window feature that some cars have, the driver holds the button shut for a little longer and the motor keeps running until the window fully closes or the driver hits the switch again.

also the pin may be floating. Low chance of that, but its possible