understanding the ignition switch
 

Used as a power distribution point in my 1985 Carrera 3.2:

http://forums.pelicanparts.com/uploa...1425523758.jpg

Starting at the top going clockwise:

R - 1 medium gauge yellow wire provides power to the radio - it is hot in all key positions except off.

15 - 1 large gauge red/black wire which Ys at a connector and then feeds fuse box 1 fuse 7 in powering several items. Powered in the RUN and START key positions.

50 - 1 large gauge yellow wire to power the starter solenoid. Powered only in the START key position.

P - 1 medium gauge gray wire provide power to the turn signal and headlight dimmer switch in the OFF key switch position only.

30 - 1 large gauge red wire that is the always hot feed from the battery into the switch. This is connected to a smaller gauge yellow/red wire to an inline fuse to the radio and a large red gauge wire to the light switch.

X - 2 large gauge wires - one is red/yellow which goes to fusebox 1 fuse 5 for heating controls and outside mirror circuits. The other is red/white and goes to position 75 on the light switch as the main power for the lights. This is powered with key switch in positions ON and RUN only.

30 - the other large gauge red wire through the bulkhead connector that is the always hot feed from the battery into the switch.

I hope this is useful and has not already been detailed. I apologize in advance if I have made any errors.

Very useful, thanks for your contribution.


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On the topic I now have two ignition switches, one with a 911 part number and one with a 964 part number.

The 911 part doesn't have any ignition lock out (where you have to return the key to vertical before starting again, so you don't try and start an running engine) but the 964 part does.

The 911 ignition lock I have appears to have the ignition lockout on the ignition lock itself.

If I am correct it seems that for the 964 they changed the switch to include the lockout.

Awesome, thanks very much for this! Plan to print this and put it in my Bentley manual.

How do wires plug into those cavities? Banana plugs?

No. This electrical module plugs into the back of the mechanical switch. The wires extend out the back of the module in the photo. The wires are crimped onto the back side of the female contacts you see. You can physically grab this module from behind and pull it to disconnect it from the mechanical switch.

What is interesting is how easy it would be to hotwire this car. You just need a mating module with switch. Of course the steering wheel would be mechaically locked.

The other thing I am thinking is that the designations of these positions on this module define power buses that are used throughout the schematics. Look at the Bentley or Haynes and where you see the X or the P etc, it appears to relate back to these power feeds.

bump for a helpful thread

Outstanding info on the ignition switch!

I have printed this thread and it is in a reference folder beside my maintenance manuals.

Thanks for taking the time, and for sharing, this valuable information with us.

Useful. Which is the one for the dash lights that everyone says needs to be fused?

My 79 SC is different in wire designation and connectivity. It has a radius of spade type connectors. I'm sure there will be some differences in model years as well. Your reference is for what year model.
jlex my 79 has uses black/blue wires for dash lights, highly recommend adding an inline fuse to protect this circuit. Do a search I know there is a really definitive thread on this mod.

Also it would be hard to hot wire as the sockets look shallow but I'm sure a jumper can be made up to send power from the feed to the fuel pump, ignition, DME and anything else needed to drive away. The mechanical section with the key would also keep the steering locked so can only go in whatever direction the wheels are pointed.

Always great info to have available, saves trying to figure out those wiring diagrams when time or availability is limited.

Thanks SpyderMike nice to share wish I had done this on mine when I was digging in to pass on. Time and no camera than.

Terry

Thank you!


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Terminals are soldered in the plastic body.

http://forums.pelicanparts.com/uploa...1466796894.jpg

Here is a '74 I rebuilt for someone with all new wires and 6 pin connector as someone had spliced into the larger red wires.


http://forums.pelicanparts.com/uploa...1466796957.jpgz

@SpyderMike, this is very helpful advice... have you ever considered writing a tech article for us? You can get 10% off you next order (no max on value).

I will check it out Roger, but really, Dennis (Timmy2) should be writing some tech articles...he knows this stuff.

Great info, our issue is no incoming power at terminal #30. From what I can tell this is s direct line to the + terminal of the battery?

Granted our 911s is 40+ years, is a rewire in our future?

thanks in advance

What year is your car? This info is from rewiring my 1985.

There are a couple of terminals #30 on the ignition switch - two wire feeds in and one out to the light switch. The two in come in through he bulkhead connector. The one out goes out in teh loom to the light switch. Have you checked for voltage on all? The two feeds in are discrete wires from the battery into the switch, but in the same loom IIRC. They are direct from the battery to the ignition switch through the bulkhead connector. You might check the power at the bulkhead connector and check the single point wiring connection at the battery. I don't think there are any splices or other connections in that run from battery to bulkhead connector.

Using the image above:
http://forums.pelicanparts.com/uploa...1469408680.jpg

Mike,

Our 911 is a 1975 S model I tracked it down to a faulty ignition switch. During prior testing I did not have 12v at terminal #30, but found the small round six connector plug was loose. After more testing I was able to spin the engine over by shorting #30 and #50 at the harness end. Then I proceeded to remove the ignition switch (a little tricky for an old guy) and checked continuity between #30 and #50 in the starting position. Nothing. A new one is on the way from our sponsor.

thanks for the assistance

Glad you sorted it out!

With your help, hope I can reciprocate in the future.

Thought I had it, engine cranks when I connect terminals #30 and #50 on the wiring harness, so it would appear to follow when the ignition switch is turned to the start position #30 and #50 would make a connection. However when I connect my ohmeter to terminals #30 and #50 on the back of the switch (on the bench) with the key turned to the start position I do not get a closed circuit. I am probably in the middle of the forest and cannot find any trees?

Speaking of nearby trees ... probing the male pins (red-to-yellow wires) of the circular black connector will help confirm (continuity) where you are --

Ignition effecting radio signal booster
 

Thanks for posting this article.

I seem to have an issue with my ignition effecting radio signal booster.

Radio reception is fine when turning the ignition key between position 0 and 1, when it clicks into position 1 or 2 the signal drops like the signal booster looses power or is no longer grounded, the booster is being powered by the radio.

Any ideas what is causing this?

Found this finally and have a question. Why are there three connections with #30? Is it because they are all directly connected to the battery? Also, on the upper left #30 it is positioned between what appear to be two wired plugs but the description is "THE other red wire..." Are there actually two live wires from the battery there? The "X" also appears to apply to two plugs/wires? #15 appears to cover two plugs but one looks unused.

Very helpful!!

Where is the ignition getting power from?

Terminal(s) 30 are fed from the battery.

Hi Denis,

Where and what does the grey and blue/purple wires plug into and power?

I added just replaces these with new front restoration design and im trying to find a home for them.

Now that the fuse panel is aligned (thanks to your diagram) moving up to the headlight switch, ignition switch to figure out why im not getting power to my turn signals and flasher.

Semi related, years ago, I had an issue with my ignition switch, and got a workaround for the time being as the job looked like srs bxns, and...then I had an (unrelated ) engine fire. Who needs an ignition switch when the engine compartment is see through? ;)

So, the engine is on it's way in and barring unforeseen issues (There are alllways unforeseen issues, ha) the ignition switch is still on the list.

I seem to recall you have to unscrew the large black beveled ring? and maybe drill something?...

Mine is a German import '73E.

Is there a thread or maybe a vid or tutorial someplace that I've missed? or maybe it's easy and I'm just being obtuse!

With the arrow pointing to the “feed to the light switch” which position is that on the actual switch?

Thank you

Rex

Should be terminal 30. Permanent power to light switch.

Thanks for that. Now i need to go find that position on the switch. I’m sure i have seen it here. lol. Is it me, or this year models are under served when it comes to electrical support?

I have this pic that I borrowed from here and saved for future reference. May be that's what you are looking for.

http://forums.pelicanparts.com/uploa...1704281224.jpg

This is helpful. Thank you

Is RT “Red”

Yes. "Rot" in German. If the others confuse you, try one of the online translators to check what you think it means.

The thing I learned in redesigning the electrical power distribution scheme in my hacked up backdate is that most of the electrical current for the car's systems is running through that ignition switch. Over the years, Porsche just ran with an older electrical distribution scheme and kept adding circuits/loads to it. With 35+ year old wiring and switch..... I got a bit nervous.

I found it fairly simple to add an electrical contactor and some relays to remove the all the power from going through the ignition switch and make shorter runs and I rest easy now.

Thanks for the clarifications. Piecing this together lol. This will also help the next guy dealing with a non standard wire harness situation.

There was another picture here on the form that could be helpful to this thread. It was a hand written color code wire placement. I think it was for the head light switch.

I went back to my Head light Switch and noticed, i only have one set of spade terminals that are perpendicular like #30.

#75 is either a single or snapped off.

Was there a variation of this headlight switch for a 1976S?