Parasitic draw from window circuit on '87

[3literpwr]

I've noticed parasitic draw on my '87 for some time, but seeing as I don't drive the car much, I always kept it on a trickle charger. Recently, I have been sorting some loose ends and wanted to get this one tackled before I possibly list it.

When I started searching for the issue, I found some problems with the door switched and not shutting the circuit off after I opened the door, so I replaced them and that solved that. However, I still see a draw on the window fuse when I test it with my multimeter. From what I understand, the '87 does not have a window ECM and the problem is likely somewhere else. From what I see, the windows and roof operate as normal and stop working with the ignition off and the door cycled open. Also, it looks like the relay is the original to the car.

Thoughts?

[3literpwr]

Well, after looking a bit more, it seems that I was mistaken on the fuse circuit. It's actually the interior light / clock / glove box circuit. I did recall that my clock has been on the fritz for years and when I pulled the plugs off it, the draw seemed to go away.

[Tyson Schmidt]

The window relay stays activated until it sees a ground signal from the door switch.

So if the door contact switch isn’t making good contact, the relay stays on, and draws the battery down.

[86 911 Targa]

^^^^^
Hope this helps.

Best,

Gerry

[3literpwr]

So the power window control unit is actually a relay?

[GH85Carrera]

The air cooled G body cars have very primitive wiring. The only "computers" beside the DME for the engine is the cruise control and calling it a computer is stretching the definition of computer. So yes, the control of the windows is just a relay that sense the ground from the door switch to control the dome lights.



On my 1985 there is a weird little connector, that I have to GUESS Porsche put in place for a mechanic to separate and it kills the power to the glove box light, clock and dome lights as well as the trunk light. If the mechanic is working in the trunk, or interior it prevents those light from coming on. The white connector under the center of the photo, partially under the carpet.

Mine went bad, and my clock became very hit and miss, and the trunk light did bot always come on.

If your car has a similar connector, disconnect it, and see if your draw is stopped. Your clock and interior light will no longer work, but it will isolate your draw.