understanding the ignition switch

[930cabman]

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

[930cabman]

Originally Posted by 930cabman

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

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?

[Jascha]

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

[rodeire]

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?

[88911coupe]

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.

[Simonrex55]

Originally Posted by SpyderMike

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



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 helpful!!

Where is the ignition getting power from?

[RDM]

Terminal(s) 30 are fed from the battery.

[Simonrex55]

Originally Posted by timmy2

Terminals are soldered in the plastic body.



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.


z

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.

[lateapex911]

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!

[Simonrex55]

Originally Posted by SpyderMike

Using the image above:

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

Thank you

Rex

[wazzz]

Should be terminal 30. Permanent power to light switch.

[Simonrex55]

Originally Posted by wazzz

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?

[wazzz]

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

[Simonrex55]

This is helpful. Thank you

[Simonrex55]

Is RT “Red”

[PeteKz]

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

[SpyderMike]

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.

[Simonrex55]

Originally Posted by PeteKz

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

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.

[Simonrex55]

Originally Posted by wazzz

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

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?