So it wouldn't matter what I have connected to the circuit ---- if the relay is faulty and energized as a result, the battery will be drained eventually?

Not necessarily. Consider the relay coil like a light bulb. If you complete the circuit from the positive battery terminal to the light bulb (relay coil) and back to the negative battery terminal current will flow, the light bulb will light (coil energize) and energy will be consumed.

In the simple relay system shown above this path is completed when the doors are open and the light switch provides a ground to the relay coil.

In the more complicated part the ground is provided with semiconductor logic circuits and if the logic is hosed it will be turning it on.

here's a schematic of my relay. Pardon the quality, most was done on RFFlow, the last couple bits in MS Paint. When the key is on, current flows through D1, and the coil of relay K1, closing the relay contacts. This sends power to the window switches. Current also flows through R1, and D3, again to the coil, which holds the relay closed when the key is turned off. This continues until either door is opened. The door switches ground the circuit, dropping all the voltage across R1, relaxing the relay. Since my door switches don't work, the relay stays on all the time, drawing current from the battery, through R1, and the coil of K1, until eventually the battery dies. I unsoldered D3 as a temporary fix. http://forums.pelicanparts.com/uploa...1213060630.jpg

I take it this is relay 944 615 116 00.

The 87-89 PET (my car) does list 944 615 112 02 (illustration 902-00) pos (7) but the picture dosen't look like the relay I have.

• I wonder which relay I should have
• I wonder why they changed the relay and not the owners manual.

A search of Pelican shows both relays

OEM-94461511202 Genuine Porsche Part: RELAY
- This is a special-order, non-returnable, Porsche part
(availability and shipping charges may vary).

944-615-116-00-M100 Electric Window Relay, 944 All (2/85-91), 968

Yes, my relay is p/n 944 615 116 00. Build date 12/85. As to why Porsche kept changing things, I don't know. Next step for me is pulling the door switches and seeing what I can do with them.

My '88 Cab doen't have either of the relay types installed. So I searched many threads about this function and have decided that the Cabs got the 944 615 112 02 relay to allow operation of the windows with the door open as a feature for raising and lowering the cab top. The Coupes got the 944 615 116 00 relay to allow for closing the windows and sunroof after you shut off the engine but are still in the car. I didn't find a pattern regarding Targas. And I'd be curious if there was a difference between manual and motorized cab tops too.

As a note, I think my relay might have been removed when the aftermarket alarm was installed by the PO. The system uses the door switches as one trigger for the alarm and I am guessing the convienence relay would cause problems with that. Just guessing though.

I feel kinda silly now- after all this work, the fix was to pull the door switches out and polish them up with Scotchbrite and put them back in. 10 minutes work, and all is well. BTW, this definitely fixed my battery problem. She starts fine after sitting for a week or two. Thanks to all the help from this forum.

Rob,
Can you explain a little detail of "polish them up"?
Thanks.

on my '86 targa, the driver's side pin switch would not reliably cause the interior lights to turn on (and, therefore, would not deactivate the power-draining relay for my electric windows) when I opened my driver's side door.

Although I ended up replacing the switch with one purchased from our sponsor, after removing the old switch I found that a bit of corrosion on the surfaces that are supposed to meet when the switch is closed (door is open) was preventing the switch from closing completely. It's easy to see and understand once you remove the switch and I believe that Rob was simply referring to cleaning the contacts on the back of the switch with scotchbrite, etc. to expose bare metal on the contacts and again allow the contacts to work. Or, you can simply replace the switches . . .

I would guess "burnish" (if you will) "nice shiny metal"......then a good coat of what's necc.

Best,

Doyle

did you guys have to take the door panels off to pop the switch out, or just pry it out?
Thanks.

There's no need to touch the door panel, it's the switch in the door jam that controls the interior lights, that we're talking about. Pry the rubber cover off, undo the switch, and pull it out. You'll see how crude the switch design is. It's a good thing though, it makes it easy to fix. Seen here-
http://www.pelicanparts.com/cgi-bin/smart/more_info.cgi?pn=928-613-147-00-M100&catalog_description=Door%20Light%20Switch%20% 28%32%20per%20car%2C%20sold%20per%20each%29%2C%20% 39%31%31%20%28%31%39%38%30%2D%38%39%29%20

rnln,

I recently fixed this little problem...very simple. The switch is located on the front door jamb, and can be removed by the center nut. Gently pull the switch out of it's mounting hole, and gently clean every contact point with a small brass brush (or whatever). Also clean the switch mounting hole, as it acts as a ground. It is usually dirty or corroded, and is usually the main source of interior lighting problems.

Put a small dab of di-electric grease on the contacts, and gently re-assemble.

oh ok. You meant the door switches, not the power window switches.
Thanks.

Hi there...I just bought an '88 911 coupe and have a battery drain issue. I'm battling this electric window problem (they always work when the key is out of the ignition and after I open any of the doors). I've cleaned the door switches that trigger the interior lights, one of them was bad and now the interior lights work as they should. This did not fix my problem as the windows still work when the ignition is off and the doors are open so I figure my power window relay is a in need of replacement.

My question is, where is the power window relay located? I have found part number: 944-615-116-00 (i've attached a pict) on PP that seems to go in the fuse box in the bonnet, but I've read that others are talking about a relay that is behind the instrument cluster.

http://forums.pelicanparts.com/uploa...1278170081.gif

I'm a noob in the DIY dept, but am really getting into troubleshooting the smaller stuff that I can handle but this one is driving me crazy.

Is this the correct relay to replace?

BTW, here's a picture of my new car. I am absolutely in love with it!

http://forums.pelicanparts.com/uploa...1278170257.gif

http://forums.pelicanparts.com/uploa...1278170278.gif

Thanks,

Chris

Chris,

Here you go............

Good luck,

Gerry


http://forums.pelicanparts.com/uploa...1278173435.jpg

Thanks Gerry...it this relay accessible from the front bonnet or do I have to pull the gauges in the dash and get to it from the front?

Chris

Chris,

Best to pull the steering wheel, then the gauge.

But first, how do you know It's the relay?

Gerry

I don't for sure...I have to check the current across all of the fuses to see if the drain is caused from something else.

I have read numerous posts about the power window operation on these cars and for some reason the power to my windows is always there, even with the key out and door(s) open. I cleaned the door switches that operate in the interior lights and they are working properly.

I'll meter across each fuse to see if there is something abnormal and go from there.

Thanks,

Chris

Don't bother pulling the gauges until you've tried reaching the relays from the open trunk. Just stick your arm back there - I've never had any problem plugging or unplugging them this way.

By the way, "bonnet" means lid. The trunk is called a "boot" in UK/Europe.