2 Stage Defogger Switch - Wiring

[goldgunner]

I'm stymied and need help!

Rear Defogger switch, 2 stage (911.613.145.00)
Has 4 terminals, numbered on the switch as:
1, 2, 3 and 4.

# 3 is clearly ground (brown wire) - since it also runs to the outside of the bulb lamp
# 1 would be positive (black wire), I'm pretty sure

Here's how continuity checks:
A. Switch push in all the way ('Off'): No continuity between any terminals
B. Switch pulled out 1 notch: Continuity # 1 to # 2 (only)
C. Switch pulled out 2 notches: Continuity # 1 to # 4 AND # 1 to # 3

For this 1980, looking at wiring diagrams from both Bentley and the Porsche shop manuals, I can't determine the connections for the other 2 terminals on the switch.

The wiring diagrams show 'Terminal 58' getting a Black/Blue wire (for "Interior Lights") and the 'other' terminal getting a Grey/Green wire (from the electric mirror harness), with a Black wire attachment (to the Rear Window Defogger RELAY).

Is 'Terminal 58' the switch terminal # 2 or # 4?

Seems to me like the switch lamp ought to be 'on' whether the 1st or 2nd stage (notch) of the switch is on - but according to the continuity - it's only on for the 2nd stage.

Yea, this is a long way around asking how to wire this switch in...

Hoping for help,
thanks,
Jim

[Early_S_Man]

Rear Defroster Relay Repair

[goldgunner]

Thanks Warren - but, sad to say I need more hand holding...
Your referral thread, while primarily regards the relay - rather than the switch - does have a diagram of the switch wiring.

Problem is your switch diagram has 6 terminals (including the lamp), while mine has 5 terminals (including the lamp), and for I'm guessing the older cars - with different colored wires and maybe terminal numbers...so I'm still confused.

Help!

[Early_S_Man]

Jim,

Ok, that diagram was from an '82 SC, so yours would be the earlier version, as used from '75, I hope. The relay is the same part ... just a different diagram version, probably from a different 'new hire' engineer! The relay diagram error started with this early schematic, BTW!

Try this one:

[goldgunner]

I'm sure I'm missing something - or not understanding - but this drawing, as well as the Bentley, seems to me to be showing a single stage switch (for a single stage relay and heating).

But, if I'm wrong and this drawing is right for wiring this switch, AND the numbers correspond to the numbers on the switch (with the exception of the '0' on the drawing above, versus '3' on the swtich), then I could assume (scary) that my:
Terminal # 1 = Black (+ power)
Terminal # 2 = Blue/Black
Terminal # 3 / # 0 = Brown (Ground)
Terminal # 4 = Grey/Green with a Black wire to the Relay

What I'm trying to use is:
Porsche shop: Current Flow Diagram, 911SC, USA, Model 78
Porsche shop: Current Flow Diagram, 911SC, USA, Model 81, Part III
Bentley 911SC Elec Wiring Diagrams - Defogger
and your schematics,
All to start the installation of all dash switches and gauges into a brand new wiring harness.

[Grady Clay]

Perhaps this will help. This is the 911 Workshop
Manual Supplement XXXIX, 1981, page 0.1-3/85.
This basically extends the ’78 main diagram. The
prior diagrams only show the single stage rear
window heater. I think this is pretty accurate all
the way back to ’70 model. If you need, I can
post the connector locations.
“
"
© Dr. Ing. h.c. F. Porsche A.G.

If you need, I can e-mail you this at 9.2M resolution.

Do you need the wire colors made clearer?

Remember to note the error that Warren found
in the Rear Window Defogger Relay. This diagram
has the error.

I reverse engineered the relay. I confirm Warren’s
correction. I need to clean up the circuit diagram
and will post it here.

It will be helpful if you can photo-document the
wiring from your 911. This is an area that Porsche
was slightly shy on documentation. Images at the
switch and the connections to the window will help.

Best,
Grady
gradyclay@hotmail.com

[goldgunner]

Thanks!
As soon as the missus finishes dragging me out to dinner I'll take and post pics of the switch and the current area of interest of the harness.

Yes, please: I'll need a clearer/finer schematic to pick up the detail of wire colors, etc.

jimd@transpec.com

[goldgunner]

Here's a photo of the rear window defogger switch, number labeled as is the switch:

[goldgunner]

Grady - Please allow me to take you up on both offers:
> Post connector locations
> Email schematic at 9.3m resolution

Thanks!
Jim Disharoon
jimd@transpec.com

[goldgunner]

Grady - upon further reveiw - your schematic is the same as Warren's in the link. So, the schematic - for me - isn't helping...

[Early_S_Man]

Jim,

The pic/diagram I posted above is indeed for a two-stage defoster! The big confusion is that it includes a front windshield heater circuit, too. If you leave out the J-47 relay, J-45 diode, and Z-2 heating grid .... the circuit applies to your car!

There is a mistaken assumption in your postings! Terminal #3 is NOT ground ... it is a switched power signal to the 2-stage relay for the second position/detent! The Brown ground wire needs to go to the center terminal of the lamp -- the unlabeled 5th terminal of your switch picture. The #2 & #3 terminals need to be jumpered together ... in order for the lamp to be illuminated in both switch positions. The relay terminal #86 [corrected diagram below] needs to be connected to terminal #2 or #3 of the switch. The wire color can be determined at the relay socket terminal. Likewise, the wire color for relay terminal 87a to switch position two -- terminal #4, can also be determined at the relay socket.



If you have the factory service manual, here is the page you need to be looking at:

[goldgunner]

Super thanks Warren~! I think we're getting there now!

I do have this 'Additional current flow diagram' for the rear defogger...I didn't look 'early' enough in my book to find it...but I've got it now.

What you've noted makes a LOT of sense.

I'll be working on this, if not tonight, tomorrow and I'll try to decipher and apply the meaning of it all.

Really, really appreciate the additonal help and the effort it represents.

As I noted above, I'm installing ALL new harnesses completely thru the car. So far it's turning out to be a probably too ambitious project based on a too optimistic expectation that the schematics compared to the harnesses and the components would make discernable and logical sense...

I'm still confident, but I'm currently performing an organizational effort to help:
> Photos of each harness with each terminal numbered
> Spread sheets describing each wire (color code, size) and termination (number of wires, terminal type and size)
> Tracking and adding 'to' and 'from's with schematic codes per the Porsche diagrams

A long way around the block, but so far it looks like it will pay off in understanding and application.

You'll be seeing more cries for help from me...let me know when you reach your tolerance level...

Thanks again,
Jim

[Early_S_Man]

JIm,

Here is an edited version of the ['75 - '80] schematic without the windshield defogger option:



Good luck!


p.s.

The two-stage defogger was always standard on Targas with fixed glass rear window, so this schematic may apply to all early cars, too. I have not checked to see if my car has a different switch, or not. I do know that it has the same relay which I disasembled [NOS spare] displayed here:

[goldgunner]

Warren - Your help has achieved the desired result - I can wire this defogger switch! Hurray and Thanks!

One final question, though:
The 'main' wiring schematic shows the wire from the Relay 86 terminal connecting at the switch with the Grey/Green from the Electric Outside Mirror Defogger. Any reason not to 'piggy back' that Grey/Green terminal onto the Switch terminal (# 2 or # 3) along with the Wire fromt he Relay # 86 terminal?

Continued thanks!
Jim

[Grady Clay]

I took this one apart:


I think it is from a ’70.
Here is the controller circuit board and a draft of the circuit:

I need to check for accuracy and draw a nice version.
(I’ll edit out this version.)






Warren, What is Q1? It is in the same case as Q2 and has
three wires, one is NC. I drew in a Zenier diode but it
probably acts as a temperature sensor. Can you please
write a description of the functioning of the circuit, my
skills are receding memory.

Best,
Grady

[pope]

My 1970 has a single stage circuit.
Photshopping of SL35 off of http://members.rennlist.org/911pcars/WiringDiag.htm



35: heater switch
51: heater relay

The heated window is bottom left.

[edit]
I measured its resistance at ~25MOhms
[/edit]

[LM3929]

subscribed

[hellblau82]

Hi guys

Just looking at inställning ny defogger switch

I seems it only pulls out one notch and also the dial seems to turn a notch

I have a two stage heater at the rear windshield with relay and cables installed

In the frunk the only relevant cables I can find are four cables

Black
Black white
green white-this has a piggyback connector on it
Blue black

My switch has 6 tabs

1
2
3
15
31
58

Anyone help me join the dots here

I can't see any red power cables remaining I'm guessing I steal this of the cig lighter?

[timmy2]

Turn function is for mirror defrost. You need a two stage switch.
Green white may be for the mirror? Keep digging in the schematics.

[hellblau82]

Originally Posted by timmy2

Turn function is for mirror defrost. You need a two stage switch.
Green white may be for the mirror? Keep digging in the schematics.

This is the stock switch that came with the car?? Why would I need another switch?


The cable in question Is definitely terminated going through the tunnel...in that tunnel loom there is 2 green whites and one white green it's much thicker that the other cables

It's the white green cable I don't know where it goes from the tunnel