Where do rear window defrost wires unplug?

[aigel]

Doing the rear window seal on my 81 SC. So far so good. Got the window out and disconnected from the wiring. Now I need to get the wires off the car and out of the old window rubber, so I can install them in the new rubber.

I read that the wires disconnect between the source / fuse box and the place where they feed into the rubber. Where is this???

What type of connectors are used? I can not find a plug-connection. If I don't find them soon, I will have to make my own connections! Is that what needs to be done??? If yes, what type of serviceable connection is recommended?

TIA, George

[BGCarrera32]

On my Carrera, the wires fished under the rear deck pad, through a grommet in the fire wall on the drivers side, and ran into the fuse/relay block shelf in the driver's side rear corner. There was a connector buried in there, or you could disconnect the wires from the fuse block and pull them through.

Edit: all the connections I'm talking about are in the engine compartment, just wanted to clarify.

[aigel]

Thanks BG. There is four wires and they go through the grommet just like on your car. Then they split, somewhere underneath the fuel filter and run towards the fuse panel. There is no connections anywhere on that stretch. I will have to take the panel off and see if there may be connections. If not, hopefully the wires all end close by and can be disconnected there ...

Thanks, George

[no substitute]

If I remember correctly there was a multiple connector, or connection point under the rear shelf/seat back assembly. This unscrews and slides up and then out. It's been a while but I think there are two metal tabs on the back of the assembly that slide into corresponding slots on the sheet metal. It comes out fairly easily.

[troy]

If it's the same as my '76 there's a multiple connector in the L/R corner of the engine compartment adjacent the relay/fuse panel. The connector on my car would not fit through the hole in the rear shelf, so I had to "un-pin the connector itself to get the wires through the hole, re-fit the wires in the seal, and then once the wires were back through the hole, re-pin the connector and you're done.

[BGCarrera32]

What troy said...and my connector was stuffed up behind the aluminum fuse panel thingie...you might have to fish it out of there.

[aigel]

Well, I found it. Four wires, all right. Two of them connect into a single eye that is bolted to the inside of the fender. They are ground wires. There is more grounds going there, e.g. the lid light etc. It is hidden behind fuel filter and accumulator. 13mm nut.

Then the other two wires go to the relay and the connector was squeezed underneath the panel, just as BG had it.

Some pics of the mess taken out. I also had to disassemble the connector like troy. I also had the black insulation on there that had to come off. Will be interesting if I can slide that back on. If not, I'll go with larger shrink tubing that I have floating around.

Thanks guys, this should do the trick. I am not looking forward to massaging the seal now, there is about 12 holes to poke!

Cheers, George

[aigel]

Well, few hours later and the window sits on the workbench, wires, seal and locking trim installed, ready to go in the car. I did it without a sip of alcohol which is amazing. Now, was there a Saint "unmentioned" in the process? That's another story...

I definitely recommend you do the windshield first before attempting this. It does not help that today's replacement part comes with no holes and no wires installed.

Someone had their head up their behind when designing this. There must be a better way! I had thought there were a few wires to take care of and tackled this a bit naively. Boy was I wrong! They have about 10 yards of heavy gauge wire crammed in there with two wires on top of each other in most places. The only place where there aren't wires gong along the window channel is the top which of course tends to leak the least.

This is a typical example of a later 911 mess. The company tried to add luxuries without willing to drasticly redesign the car. It's like the dash that they kept the same for 25 years and added little switches in arkward places where there was still room. That wiper delay switch they stuck beteween the gauges is ridiculous... This probably was somewhat customer inflicted (nobody wanted the 928 or other potential new flagships), but gimme a break. I sure would have been upset if I had paid close to 40k for this car in 81...

I think practically all German auto makers were guilty of this 'warming over' stuff. If you look at the Beetle or Opel's line of cars, it is quite amazing what they sold you for 'new' in the 70s and 80s. They changed the trim a bit, but that was it... of course those cars were cheap, approximately a fifth and less of what my 911 did cost back then.

Time to hit the sack. Tomorrow I need to get some of the interior bits back while I can get there nicely with the window out. And then get the wife to help with roping the window back in for a dry ride!

Cheers, George

[aigel]

Just wanted to say thanks again and update y'all. After only about 10 minutes of garage time with the better half, the sucker is back in and it looks great. We had to move the window around a bit for the best position (after install! Thanks for suction cups!) First leak tests in the garage with a cup of water in the bottom corners turned out negative. Dry, I mean!

Now, will my rear window defrost still work? We'll see. I doubt I'd pull everything again if it should not. It sure was tempting to leave it all out and I am proud I at least took a good shot at it!

The best new thing I learned on this window vs. the front windshield? Put the entire roap in soapy water! That did really help roaping it in!

And to all folks that say that they rather have this done: I think it isn't hard at all. It is a PITA, needs patience etc. but it isn't bad. The argument to do it yourself really is: Who would do this right w/o you paying a fortune?

Cheers, George

[onewhippedpuppy]

That's a good point George, I did mine wrong for free. It is a royal PITA, but at least when I do mine again I'll know what I did wrong. I got so pissed I left out my defrost wires, it didn't seem to work anyway.

[hgray]

Aigel

The bottom 'section' of my rear window defroster doesn't work (the top two sections do work). I suspect a main wire has come loose.

Where should I start to trouble shoot this, based on having just done all your work?

TIA

[exc911ence]

Can anyone snap a pic of the fuse box in the engine compartment where the rear window defogger attaches? I've traced my wiring down to the relay and onto the fuse but there's no wire on the other side (aft) of the fuse! And I wondered why it didn't work...

Anyway, I can't seem to find any spare wires anywhere so it would help to know what colour it's supposed to be and where it runs after it leaves the fuse block.

Thanks!

[RoninLB]

I snipped the wires when they were under the deck/inside the engine comp. I removed the rest because I never use the defroster. It gives extra room when going aftermarket ignition. It'll be a simple reinstall if necessary.

[aigel]

Originally posted by hgray
Aigel

The bottom 'section' of my rear window defroster doesn't work (the top two sections do work). I suspect a main wire has come loose.

Where should I start to trouble shoot this, based on having just done all your work?

TIA

hgrey:

Assuming you have the same wiring in your rear window than I do in my 81SC, I'd find the connector and measure if you have a connection to ground on both contacts. If you do, likely something in the rubber or window area is messed up. You will see why I think that is...

There are two wires going "in", and two ground wires going out. The wiring in the window is a bit more complicated. I wish I had taken notes but here is what I came up with from the top of my mind. Note that the colors are not the true wire colors. You can see what they look like in the pics that I took. Basically there are two cirquits that are fed separately, the center and the top/bottom. That is why I suspect that if the bottom is out, it is a problem upstream of the connector!



If I remember right, the two grounds went in on the pass. side, while the hot wires went in throught he driver's side. The connecting wires in the window that make contact for the top were black.

Hope this helps. I hope people can comment if I got it right from the top of my head. Off to the garage to check mine!!! I will take some pics for the other inquiries.

Cheers, George

[aigel]

Looking at the diagram again, your open cirquit can really only be in the window element itself, or the connection between the window element and the connector. The connector that the two wires (black and the others) goes on is a solid piece of metal with tabs on both ends. There is no way it would loose connection betweent the black wires feeding the top and the wires feeding the bottom!!!

I went and measured my resistance. Both connections read exactly 2.0 ohm. That makes sense, giving you a 6A current at 12V and a power of 72W per cirquit.

Now I also counted the cross wires on the glass. There is 7 to the bottom, 9 to the center and 3 to the top. So, one cirquit has 10, the other 9 crosswires evening things out nicely.

I would expect that you'd measure considerably more resistance than 2 ohm in the top-bottom cirquit if your bottom is out because thosewires are in parallel. Because your cirquit would go through 3 instead of 10 heater wires, your resistance should be 2 ohms * 10/3 = 6 2/3 Ohms.

I hope someone can chime in here before you toss your window.

Cheers, George

[k9handler]

I have a question for you guys, only my top element works...what would cause that, and could I simply jump the wires to work the lower elements?

[aigel]

k9handler:

That only would work if your problem is in the supply of the juice, not in the wiring of the window!

I am learning myself here, but I think it is +12 V to both of the connector's contacts. I guess the heating relay box might alternate the juice between those two cirquits or do something else to spread the joy...

I'd recommend measuring resistance on both connector pins against ground and see if it is the same. If one is considerably higher or zilch, the problem is upstream from the supply and switching won't help you.

Since the top and bottom are a unit, I'd think something in the wiring / window is fishy if only the top works, w/o the bottom.

This all said, I hope someone can confirm that draft of a wiring diagram that I threw up here! It all depends if that's correct, but if you read my thinking out loud above in the edited comment, it seems to all make good sense.

George

[aigel]

Originally posted by exc911ence
Can anyone snap a pic of the fuse box in the engine compartment where the rear window defogger attaches? I've traced my wiring down to the relay and onto the fuse but there's no wire on the other side (aft) of the fuse! And I wondered why it didn't work...

Anyway, I can't seem to find any spare wires anywhere so it would help to know what colour it's supposed to be and where it runs after it leaves the fuse block.

Thanks!

exc911elence:

Does this pic help? I posted it separately to get an answer to another little problem that surfaced!

What is disconnected here: 81SC rear fuse panel area?

The fuse panel in my 81SC is fed with a pretty fat harness that has a large connector coming from the back into the bottom of the fuse panel. I think you will have to remove the panel and trace the wires from that connector.

HTH, George

[hgray]

Aigel

thanks alot, that helps!

[exc911ence]

Originally posted by aigel
exc911elence:

Does this pic help? I posted it separately to get an answer to another little problem that surfaced!

What is disconnected here: 81SC rear fuse panel area?

The fuse panel in my 81SC is fed with a pretty fat harness that has a large connector coming from the back into the bottom of the fuse panel. I think you will have to remove the panel and trace the wires from that connector.

HTH, George

Funny, yours doesn't have any wires on the aft side of the top fuse either... so why isn't my defroster working?!?