justinsrx7

I finally got back to troubleshooting the switch today and the plug suggestion from tpd83911 seem to be tight. What I did notice though is that when the key is in the on position, the yellow wire going to the drivers side window switch gets very hot and it heats up immediately. Funny thing is that when I put a voltage tester on the yellow wire, it is not live, so why would it be getting hot. See the picture below to see which wire I am talking about.

I am not an electrical guru, but if anyone that is has some ideas, I'm all ears.

theiceman

Sounds like the motor is over driving .. and not turning off .. let me chack my Bentley . i think yellow is in fact 12V .. try removing it fom the switch and measure between the yellow wire and ground. i bet you have 12 volts.

Aquaholics

Hi Justin,

Assuming nothing changed from my 76 911 to yours then the yellow wire and the black wire both lead to the window motor and the other three are +12volt x 2 and the brown being earth.

If you have a test lamp or multimeter then put the earth to the car body somewhere and the positive on each pin one at a time with accessories on. You will find all have +12volt on all except the brown wire. Then push the switch either up or down and the yellow wire or the black wire will lose it's +12volt.

Reason being is the yellow and black wire go to the window motor and the motor goes up or down depending if it is fed +12volt or -12volt.

Simple test, turn the car off. Disconnect the yellow and black wires going to the window motor from the switch and connect one to 12volt and the other to earth (using another car battery or a battery charger with a supply function or something like that). Only do it for half a second and you should find the window will move or try to. Reverse the wires and it should now more. If not then sounds like you have the same as I have nutted out this morning, a dead window motor.

I hope the above helps and makes some sense. It is what I have nutted out this morning on my 1976 911 so I think you will find things are the same on your 78 911.

Best of luck,
Ben

justinsrx7

Thanks for the info Ben. It was very helpful. I tried your recommendation and the motor worked so the attention turned to the wiring of the new switch and it turned out a couple of wires were mixed. Once that was rectified, the window worked fine.

Thanks to everyone in this thread for your help!

Aquaholics

Glad to hear.

Reuben981

I need some help. My passenger door will not close without slamming the door a few times. However it closes perfectly the first time if the drivers door is open or the passenger window is open.

I want to install a time delay relay using the door light switch as a trigger. When the door is open the trigger will lower the window for a few seconds (x) and when closing the door the window will close the window for x seconds.

Which wire/s on the switch controls the up and down function movement ?

AG81

Red/black & Red/white are definitely the wires you need on that switch to control up & down function. Not sure which is up and which is down. Brown is ground..... Green & Black go to the window motor.

luke-44

When I tire into my newly acquired and all original 88 last spring I had at first assumed window motor after checking the switches.

But when I got it all apart the real culprit was the dried out and hardened 31 year old track grease. Too much load and the motor just can’t/won’t turn. Cleaned up the track, regreased and voila good as new. Food for thought.

autobonrun

Do you recall what you used to regrease the track? I need to do the same while mine is out of storage for a few weeks.

luke-44

Yes, I used good ol’ wheel bearing grease for the gear mechanism and white lithium grease for the tracks.