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Dissecting the ignition switch electrical (wordy w/ pics)
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ashman40
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PostPosted: Thu Mar 17, 2011 6:55 am    Post subject: Dissecting the ignition switch electrical (wordy w/ pics) Reply with quote

I've been wanting to document how the internals of the (electrical) ignition switch work and also show the weak spots to demonstrate WHY a "hard start relay" could be needed. Hopefully this will answer questions some may have and correct some misconceptions. So here goes....
{any "funny colored" pics are because I tried to lighten them so you could see the dark/shaded areas better}

Outer View
The electrical portion of the ignition switch is located inside the ignition lock assembly metal body (#1 below). This lock assembly is installed in the steering column housing. This is what the ignition lock assembly looks like:
Image may have been reduced in size. Click image to view fullscreen.

The shape has changed over the years, but related to the ignition switch, this housing has three parts:
Image may have been reduced in size. Click image to view fullscreen.

A : The ignition switch (left) that controls the flow of electricity to different components of the car.
B : The lock cylinder (right) where you insert the key.
C : These dimensions are meant to help you drill a hole to press the release spring for the lock cylinder.
D : The lock assembly which extends/retracts a steering column lock bolt depending on the key position. The other two parts fit INTO this housing.

This is the (failed) 2yr-old ignition switch from my '75 RHD 1200LS (non-US). It uses a 1971 ignition switch (why?... because it uses a 1971 steering column -- the last year without the steering column mounted wipers -- so you can still fit the earlier style steering wheels).
Image may have been reduced in size. Click image to view fullscreen.

Notice the bump at the bottom used for proper alignment and the threaded tab at the top where the small screw holds the switch into the lock assembly (#2 in the pic above). If the tab breaks off, this switch is probably not worth fixing. No amount of glue will work to hold the tab in place and prevent the switch from falling out of the lock assembly body.
Note the center keyed slot. The end of the key tumbler assembly passes through the entire lock assembly and fits in this slot. When a key is inserted, a small pin extends and touches a brass tab inside. This causes the Brown/Blue (#SU) wire to become grounded to the body of the lock assembly.
If this keyed slot is badly chewed up, the switch may not work properly.. or at all.
The whole switch is a nice fit into the key assembly body. If you think you can glue or tape the electrical switch together... you may find you can no longer insert it all the way into the lock assembly body. So be careful to preserve the outside of the case and not break any tabs/clips.

{Continued in the next message...}
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ashman40
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PostPosted: Thu Mar 17, 2011 6:56 am    Post subject: Reply with quote

So what are all the wires for?
    Red - (#30, Battery)(4.0mm^2 ~ 11AWG) 12v+ power from battery (center post)
    Gray - (?, Key OUT)(1.5mm^2 ~ 15AWG) 12v+ output while ignition switch is OFF (alarm)?
    Brown/Blue - (#SU, Key IN)(0.5mm^2 ~ 20AWG) ground output while ignition key is inserted
Image may have been reduced in size. Click image to view fullscreen.

    Black/Yellow - (#X, ACC)(4.0mm^2 ~ 11AWG) accessories that do not need power while engine is cranking, 12v+ output only in ON position
    Black - (#15, Ignition)(1.5mm^2 ~ 15AWG) 12v+ output in ON & START positions
    Red/Black - (#50, Starter)(4.0mm^2 ~ 11AWG) starter solenoid, 12v+ output in START position
Image may have been reduced in size. Click image to view fullscreen.

My original switch (before this one) came with a metal case and one(?) less wire. I was afraid this plastic one would break, but I was careful when removing the cover. The internals of the original switch were much different than the below. So please realize there are different kinds of switches out there. This write up is just a guide for the one I have. But functionally, they will be similar. Careful attention to details and you can understand how any switch works.
Obviously this OE manufacturer was using later style switch bodies and soldering wires to them for use in earlier cars.
'71 was the last year for soldered on wires. Later models used a similar switch w/ spade connectors out the bottom. If this switch fails me again in the future, I will try to use a later style switch ('72-later?, less expensive) and just crimp female spade connectors to the end of my wires.
Note the terminals in the above pic. They are staked into the black plastic base. This means they could wiggle loose. Compare how much they stick out and tap any loose ones back in. Maybe even add a dab of strong glue to prevent them backing out.... be careful NOT to get glue on the sides of the housing.

My original switch appeared to be an original VW part and may have been as old as the car, but it "died" from the same reason as this one... burnt contacts... it just took longer for the original to fail. This OE replacement failed after 2years. I read lots of post of people having trouble getting their starters to crank. I believe many are related to old ignition switches burning out their contacts. As the years pass... it will only get worse.

{Continued in the next message...}
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ashman40
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PostPosted: Thu Mar 17, 2011 6:57 am    Post subject: Reply with quote

Going in...
To start dis-assembly, you pry off the white cover from the black base with a small screwdriver. Be careful NOT to crack the plastic/nylon. Slowly separate the parts, being careful to capture any ball bearings or springs that may "pop out".

This cover contained the return spring that forces the key to rotate back from START to ON. It also has grooves that functioned as a one-time gate so you MUST turn the key to OFF before trying to START a second time. That function seems so uniquely "VW".
Image may have been reduced in size. Click image to view fullscreen.


Below you can see the black plastic mid-layer that will rotate as the key is turned. The bottom face of this mid-layer will hold springs and the conductors against contacts located in the base. The black piece flips over and into the cover. You can see the square tang that engages the return spring. This only happens between the ON and START positions so there is no rotational tension on the assembly most of the time. Also note the greasy square slot where the spring & follower sit (5-o'clock). This spring & follower are what make the one-time gate function properly. Leave it out and you can go from ON to START as many times as you wish (hint?).
Image may have been reduced in size. Click image to view fullscreen.


Here is the bottom side of the mid-layer with the springs that hold conductors against contacts. The mid-layer is properly seated inside the white cover:
Image may have been reduced in size. Click image to view fullscreen.


And with the springs installed:
Image may have been reduced in size. Click image to view fullscreen.

The brass "ring" to the right fits between the mid-layer and the base. I've oriented the "ring" and it's tab so you can see how they fit into the mid-layer. Note the slot at the 8-o'clock position that will hold the ring's tab. This "ring" will conduct ground once the key is inserted (the key is grounded via the key cylinder and the lock assembly). The pin that extends from the key cylinder will contact the brass tab. The outer ring will remain in contact with the #SU terminal even as the whole thing rotates. There is also a small spring at 1-o'clock position that presses on the small tab located on the ring. This helps maintain pressure around the ring circumference.

{Continued in the next message...}
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'75 Beetle 1200LS (RHD Japan model) {junked due to frame rot}
'67 Beetle #2 {2019 project car - Wish me luck!}
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ashman40
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PostPosted: Thu Mar 17, 2011 6:58 am    Post subject: Reply with quote

Internal contacts
Once you have the cover off you can see the internal contact pads in the base which are opposite the outer terminals and soldered wires. I have labeled their functions here.
Image may have been reduced in size. Click image to view fullscreen.

Each contact has a raised "pad". This small area is where electrical contact is made. Not much surface area!

IMPORTANT NOTE: the Starter contact at the top has a black burnt pad. This is the reason WHY I took this switch apart after only 2-yrs. The current flowing through to the starter solenoid had burnt the contacts so badly they worked intermittently or delivered less than 12v. You can also see pitting on the center lead contact point.
The original switch which I took a part had much LARGER contacts for most of the circuits. The Starter contact in that switch was almost as large as the center contact above.

HARD START RELAYS (HSR) - Based on my findings above, I personally believe any new OE ignition switches should be paired with a HSR. This is not for the purpose of compensating for bad/old wires (though it does do this too)... but to prolong the life of ignition switches (NOS ones, or even Chinese made ones). The HSR reduces the current that passes through the Starter contact in the ignition switch... preventing the burnt contact you see above.

I cleaned all the electrical contacts w/ a small emery board before re-assembly.

The other thing to note in the above pic is the circular groove cut in the base between the outer contacts and the inner one. It runs from 11-o'clock to 4-o'clock around the bottom. This grove controls when the rotating conductor is pressed down onto the contacts. A bump on the silver "keyhole" shaped (SKS) piece falls into this groove.

Along the top lip of the rim are three notches. One at 1-o'clock, one at 5-o'clock and one at 6-o'clock. These are the detents (felt as ignition key positions) they keep the key in each position. One end of the rotating conductor rides this rim. When you turn the key and feel it "click" into the ON position.... you are feeling that conductor end fall into these detents.

{Continued in the next message...}
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ashman40
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PostPosted: Thu Mar 17, 2011 6:58 am    Post subject: Reply with quote

Here are the rotating metal pieces:
Image may have been reduced in size. Click image to view fullscreen.

The silver "keyhole" shaped (SKS) one at the top appears to be made from tin or aluminum. It's main job is to help the Y-shaped conductor rotate soothly, but it also drops down to make contact between the battery terminal and the ignition + "X" circuits at the same time. This ensures current is flowing to the ignition coil as the YSC rotates between contacts. It will also lift and drop the conductor depending on which position the key is in.
The Y-shaped conductor (YSC) in the middle does almost ALL the work. It conducts electricity from the center battery terminal to the outer contacts. The two ends of the "Y" allow up to two contacts to be powered at the same time.
The ring at the right is the ground ring for the Key IN circuit.

This is how the top two pieces fit into the base:
Image may have been reduced in size. Click image to view fullscreen.

Note in the background the cover and mid-layer. You can see how the YSC will FIT into the mid-layer (see Y-shape slot in mid-layer). The springs in the mid-layer will press against the YSC to ensure good contact.

KEY POINT !!!: this above pic with the YSC in the base is for reference only. All of the conductors are assembled in the cap/mid-layer shown in the background and then the empty base snaps into the cap last.

{Continued in the next message...}
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'67 Beetle #1 {project car that never made it to the road Sad }
'75 Beetle 1200LS (RHD Japan model) {junked due to frame rot}
'67 Beetle #2 {2019 project car - Wish me luck!}


Last edited by ashman40 on Thu Mar 17, 2011 7:08 am; edited 1 time in total
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ashman40
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PostPosted: Thu Mar 17, 2011 7:00 am    Post subject: Reply with quote

Key positions...
NOTE: all below pics are examples to show HOW connections are made inside the ignition switch. The actual conductors are assembled on the mid-layer in the cap, then the base is snapped into place sandwiching the conductors and springs between the mid-layer and the base.

This is what the conductor will look like in the different key positions (it looks funny because I used a paint program (Gimp2) to paste the conductors into the earlier pic for consistency). You can compare with the earlier labeled pic to determine which contacts are receiving power.

This is the OFF position:
Image may have been reduced in size. Click image to view fullscreen.

The only contact is to the gray wire which is now connected to the center 12v+ battery source. There is no physical contact with any other terminal.
The opposite end of the YSC is sitting in the top notch around the outer rim. This prevents accidental movement. While it may look like the tip of the "Y" is touching the starter terminal, it is always supported along the rim edge. This end of the YSC never touches anything conductive. Even the ground ring which rides on this same rim rotates with the key so the tip of the YSC rides in the gap of the ring.

This is the ON position:
Image may have been reduced in size. Click image to view fullscreen.

Now 12v power is connected to BOTH the #X and #15 terminals.
The dimple of the SKS piece has fallen into the semi-circular groove now. A spring will hold it against the contacts and ensure the Ignition circuit (#15) has continuous contact with the 12v source as the key turns.

This is the START position:
Image may have been reduced in size. Click image to view fullscreen.

Now 12v power is connected to BOTH the #15 and #50 terminals and the engine should be cranking. In the stock configuration, maximum current is flowing through the Starter terminal to the solenoid. Without a HSR, arcing over time will burn the Starter contact (as seen above).
Notice the #X terminal is no longer connected (the small tab which looks like it could be touching is actually suspended above the terminals).

Closing up...
In the end, everything is assembled up-side-down in the cover and the base is finally snapped into the cover. It is likely your switch may be made differently than mine. I recommend you study the switch and understand how the contacts and springs work together.

I de-greased everything and polished all electrical contacts with an emery board or fine sandpaper. I cleaned out all the filings and re-greased all friction parts w/ dielectric grease.
I ran electrical checks of all contacts to make sure they were working as expected as well as tested the one-time gate mechanism.

Overall, it took a bit of time (two weekends of work... going very slowly). There were a few small parts that could be difficult if you are "all thumbs", but in general, I think anyone could do this themselves if they wanted to revive or rebuild their ignition switch.
Having done this twice now... given a choice of rebuilding an original ignition switch vs. buying a replacement (possibly made somewhere OTHER than Germany, 30-years ago)... rebuilding would be my first choice. I feel you would get the longest life out of the part as long as there were no broken pieces to deal with.

REFERENCES:
http://www.vw-resource.com/ignition_switch_replacement.html
Good step-by-step for replacing the ignition switch.
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'75 Beetle 1200LS (RHD Japan model) {junked due to frame rot}
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mondshine
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PostPosted: Thu Mar 17, 2011 8:15 am    Post subject: Reply with quote

Nice work ashman-
This rates "sticky" status.
Thanks, Mondshine
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PostPosted: Thu Mar 17, 2011 8:28 am    Post subject: Reply with quote

Great write up!!!

Yes a start relay and a Ignition relay will preserve that ignition switch assy.

Replacement switches that I have seen are not as reliable as OE.

Thanks for taking the time to show the assy.

Jim
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PostPosted: Thu Jun 30, 2011 8:41 pm    Post subject: Reply with quote

Awesome.
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PostPosted: Fri Jul 01, 2011 10:15 am    Post subject: Reply with quote

Superb write-up and documentation, ashman!
Glenn... perhaps a candidate for the sticky's?
(Oops..beat me to it mondshine)
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PostPosted: Fri Jul 01, 2011 1:34 pm    Post subject: Reply with quote

Another Bump for a sticky, Good work ashman. Wink
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PostPosted: Fri Jul 01, 2011 2:49 pm    Post subject: Re: Dissecting the ignition switch electrical (wordy w/ pics Reply with quote

ashman40 wrote:
When a key is inserted, a small pin extends and touches a brass tab inside. This causes the Brown/Blue (#SU) wire to become grounded to the body of the lock assembly.


That's the setup for North American ignition switches.
European ones (which we got here in Aus) are different.

They have S instead of SU and it does the opposite thing.
When the key is inserted it provides 12volts to S instead of a ground like SU.
All of my 71 and later Supers have been like this as well as the replacement switches I've bought.
Strangely though the 71 and later 1300 standard beetles I've owned were completely missing that terminal, just had an empty slot there.

It really is handy though as it acts like an accessories position.
I just have this connected straight to the ACC wire of my headunit so it only powers up when the key is in the ignition but doesnt have to be turned on.

Also your mystery grey wire that is only live when the ignition is turned off is for the side light marker system that was used in parts of Europe.

If you leave the indicator switch in left or right position once the ignition is turned off the side repeater indicator stays lit up.

This was for when the cars were parked in those dark narrow laneways in Europe so they were more visible and didn't get side swiped.

Most type3s here in Aus have that feature.
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PostPosted: Fri Jul 01, 2011 2:54 pm    Post subject: Reply with quote

You know i don't read every topic, so next time can someone PM me?

Added to the FAQS/Sticky.

thanks ashman40
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PostPosted: Fri Jul 01, 2011 5:30 pm    Post subject: switch Reply with quote

Just changed my burnt out switch today. Will be rebuilding the old one tomorrow. Thanks for the read. Really well done. Jeff
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PostPosted: Thu May 30, 2013 2:07 pm    Post subject: Thanks! Reply with quote

Just wanted to say a big thank you for this thread. I'll be replacing my switch/switch harness this weekend and wanted to have a good idea where each wire hooked under the hood since the PO screwed it all up. By using this information and the wiring diagram I now know where to properly hook up each wire.
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PostPosted: Thu Aug 29, 2013 7:17 pm    Post subject: Huge Thank You!! Reply with quote

Just wanted to say THANK YOU to ashman40 for this information!! It was excellently presented and illustrated. This is very helpful.
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PostPosted: Thu Aug 29, 2013 8:26 pm    Post subject: Reply with quote

Excellent job Ashman! This is really an incredible insight into the heart of our lovely vehicles.

On the first pic, number 2 is just one screw that holds the ignition switch in place, correct?
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PostPosted: Fri Aug 30, 2013 3:59 am    Post subject: Reply with quote

The small screw hole is the only thing holding the electrical switch in. There is (IIRC) a "nub" that sticks out the top of the electrical switch that fits into a hole inside the recess. This takes the load of the twisting action.
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PostPosted: Fri Aug 30, 2013 4:15 am    Post subject: Reply with quote

Applause
Dancing

Well done!
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PostPosted: Fri Aug 30, 2013 5:32 pm    Post subject: Reply with quote

ashman40 wrote:

And with the springs installed:
Image may have been reduced in size. Click image to view fullscreen.

The brass "ring" to the right fits between the mid-layer and the base. I've oriented the "ring" and it's tab so you can see how they fit into the mid-layer. Note the slot at the 8-o'clock position that will hold the ring's tab. This "ring" will conduct ground once the key is inserted (the key is grounded via the key cylinder and the lock assembly). The pin that extends from the key cylinder will contact the brass tab. The outer ring will remain in contact with the #SU terminal even as the whole thing rotates. There is also a small spring at 1-o'clock position that presses on the small tab located on the ring. This helps maintain pressure around the ring circumference.

{Continued in the next message...}


I'll have to dissect one of my old dead ones to see what the difference is with the S vs SU wire is.

On all ignition switches I've got after 70 the terminal is S rather than SU and is positive when the key is in not ground.

I think all that happens is the brass ring is flipped upside down and plastic cap on top so the key barrel pushes it against the 30 battery terminal in the middle rather than grounding it on the key barrel.
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