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    Thread: Pics of reverse switch failure...

    1. Member Broke's Avatar
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      08-18-2009 06:42 PM #1
      Here is a copy of some new pics and info I put on my Reverse Switch page on the site in my sig, I try to post new pics and info on the forums so more people see it and might use it [IMG]http://*****************.com/smile/emthup.gif[/IMG]
      This pic shows 3 different styles. The one on the far left is a 4-pin switch, it is on the older MK1 cars usually. The one in the middle is the most common and it is the 5-pin switch found on most MK2 cars with the upshift light. The one on the right I have no clue about! It is a 6-pin switch, and it came from one of these many trans that I have collected or rebuilt over the years. I could dig around with the part number and see what model cars used it, but it isn't as common, I only have one of them out of a box of switches. The 5-pin switch is the most common one you'll find.

      Here are the backs of the switches shown above. The left one is the older 4-pin switch, it has just 2 contacts, one for the reverse lights, one to shut off the upshift light when in 5th gear. The one in the middle has 3 contacts, the top contact being for neutral. The switch on the right is the 6-pin switch, and it has 6 contacts. You can see the switch will support up to 7 contacts, as there is still 1 hole left open in that switch on the left (the 2nd hole I think isn't for a contact, the holes with contacts seem to have guide grooves in them).

      Right, let's open an older switch up and see what makes it work. The newer switches don't come apart like this, they're glued/welded/sealed etc. at the seams, even though they tend to fall apart, as I have several here that people have repaired by sealing it back up again. This is the older 4-pin switch the MK1 folks will have...

      The older switches have little locks you need to release to get the part split open...

      Slide a thin screwdriver under the edge and lift it up over the locks...

      Flip it over, release the 2 locks on the other side, and pull the switch apart...

      The parts of the switch once split open...

      Push the internal parts out of the switch by using an empty contact hole in the switch...



      The parts of the switch are the actual metal pins where you plug the wires into (in the background), the rectangle block in the foreground is where the small pins are that complete the circuit, they are spring loaded plungers with metal pins on the ends. The black rubber piece is a seal to prevent trans fluid from reaching the spring loaded pins, or the metal pins on the piece in the background. The portion of the switch that sticks into the trans with the contacts that are pushed by the selector assembly inside is shown on the right, partially out of frame...

      The internal spring loaded pins in the block and the rubber seal are notched so they only go in one way. The rubber seal allows the movement of the contacts and the spring loaded parts to pass back and forth without allowing oil to pass. It reminds me of those rubber layers you find when you open a TV remote control or a pocket calculator....


      Here is looking into the body of the switch that is put into the trans itself... the contacts are what can sometimes wear out and wear down from the steel selector rubbing the plastic contacts over the years, making them too short. That is one way for the switch to not work. If you have a bad switch in the trans, but pulling it out and pressing the contacts with your fingers makes it work, the plastic contacts might be bad.

      Here is the spring loaded block.. the contacts in here are plastic, spring loaded, and the ends have metal pins in them to complete the circuit. The metal pins are pushed in between 2 spring bars to complete the circuit...

      This is the portion of the switch housing that you plug the wires into... the pins are molded in and bend to form these spring bars. You can see that there are 8 bars... with 4 of them just single bars. Those are the 4 missing pins where you plug the wires in. The pins just aren't extended. The 2 sets of 2 bars which make a pair of spring bars in each corner on the bottom row are the 4 pins you plug the wires into.
      The set on the right in the pic are for the reverse lights, the set on the left are for the 5th gear and upshift system. Notice the burn damage around the reverse light bars, and this is after I picked at them to clean them up again...

      This is the other side of the spring loaded block, this is the side with the metal pins that are shoved into the spring bars shown above, they complete the circuit. The one on the left is reverse, the other 5th. Notice the burn damage around the reverse pin, and how the end of the pin looks different than the 5th pin. I've cleaned it up, but you can still see damage, it was covered in a crusty build-up of carbon. This is what makes the switch fail... the amps needed for the lights is just too much for these wee pins over time with corroded connectors. Each time it is activated, it burns a little of the pin away. The bars are thick and can take it, the thin hollow pins just melt away.

      From this angle you can really see how the reverse pin is melted and much shorter than the 5th pin. This switch wouldn't work at all. Sometimes the switch will work on the bench being worked by hand, but not in the trans. That could be worn plastic contacts, as mentioned earlier, but it could also be a pin melted away just enough to still work when you shove the contact in all the way, but not enough to work when the selector moves it in, maybe not quite as far. Normally, it would be enough, when the pin was new, but it might be just burned enough to not work in the trans, but work on the bench.

      There you have it... if you're very handy, you can fix this with a home made pin, or by swapping pins and getting rid of the 5th switch by jumping the wires and killing the upshift system, or you could solder a bit on the end of the bad pin then shape it to extend the pin again... it can be made to work again, and could be rebuilt. That's the cool part about old things... the way they're built usually allows you to rebuild them. With the new sealed switches, it can be done, but it is less simple as it is probably vibration or ultrasonically welded, and splitting it might break it. The old switch is easily taken apart and put back together.
      If you want to make the switch last a long time, relay the reverse lights.
      Just like you do with the headlights, use a small relay to power the reverse lights, and don't send the full amp draw through the actual reverse switch. Someone said they checked on a 4-pin switch recently and found it for $50 new, so it might be the way to go if you want to make it last. The other option is to move the wires around in the connector plug on the wiring harness, and use a 5-pin switch which is cheaper at $35, but it's likely to burn up as well. A relay would take care of the switch burning up. If you like to tinker, it might be worth it.
      020 trans info pages - www.BrokeVW.com
      NEW 0.7619 5th gears for the 020
      NEW 020 reverse gears
      '86 GTI 8V 2.0L -'88 Scirocco 16V - '10 F150 4x4

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    3. Member tolusina's Avatar
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      08-18-2009 08:48 PM #2
      [IMG]http://*****************.com/smile/emthup.gif[/IMG]
      Quote Originally Posted by kamzcab86
      I hate reading: "But I bought this car for $500 and don't want to put another dime into it."
      ____(hey, it's VW AND it's electrical, what's not to fail?) neoBentley+



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      08-21-2009 02:26 PM #3
      Broke,
      YOU DA MAN. [IMG]http://*****************.com/smile/emthup.gif[/IMG] Great write up.
      -dasdachshund
      -------------------------------
      A cowboy was out riding when a dude came along and hollered, "Git along, little doggie!"
      The next day the cowboy showed up with a dachshund.

    5. Member tr.:R's Avatar
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      08-21-2009 03:08 PM #4
      so this is why my reverse lights dont work?

    6. Member sprocket007's Avatar
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      08-22-2009 01:44 AM #5
      That is great It is always nice to learn more and get some great pictures!
      BSc.N, EMS/FIRE

    7. Member dandydanny's Avatar
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      08-22-2009 06:47 AM #6
      http://www.brokevw.com/reverseswitch.html
      Wow these big switches sends 5th gear, reverse, and neutral gear selection information? The signals would come in handy when adding electronic gizmos, especially neutral and 5th gear (remote start, shift-up indicator).
      Would my 92 accept this type of switch? I have the dumb 2-pin screw-in type at the moment.

    8. Member Broke's Avatar
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      08-22-2009 07:44 AM #7
      Quote, originally posted by dandydanny »
      Would my 92 accept this type of switch? I have the dumb 2-pin screw-in type at the moment.

      Not without changing the trans case, or the entire trans, unfortunately. They accept one or the other.
      020 trans info pages - www.BrokeVW.com
      NEW 0.7619 5th gears for the 020
      NEW 020 reverse gears
      '86 GTI 8V 2.0L -'88 Scirocco 16V - '10 F150 4x4

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      08-22-2009 08:07 AM #8
      Thanks for posting these, Broke. These photos (along with the reverse light wiring page on your site) would have come in handy when I was attempting to figure out which pins were which several years ago since a 9A with this switch was swapped into my '89 at some point before I bought the car. [IMG]http://*****************.com/smile/emthup.gif[/IMG]
      My flying/aerial/scenic/transportation-related photography: http://www.flickr.com/photos/vfr_photography/
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    10. Senior Member dubdaze68's Avatar
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      08-23-2009 12:56 AM #9
      I could never figure out why VW decided to use plastic in a piece that gets dipped in hot gear lube repeatedly through a lifetime.
      At one point the Scirocco 16v one was backordered for close to a year. I hate the smell of gear lube enough to have never tried this, but might give it a shot now.
      DCIVW
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    11. Member Broke's Avatar
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      08-23-2009 01:23 AM #10
      Quote, originally posted by dubdaze68 »
      I could never figure out why VW decided to use plastic in a piece that gets dipped in hot gear lube repeatedly through a lifetime.

      There is plastic inside the trans all over the place. The diff has a large one piece plastic thrust washer in it. All 5 forward gears spin on needle bearings in plastic cages. The input shaft ball bearing has plastic shields on it.
      The plastic is fine in oil, that's not what makes the switches fail, it is the current being pulled across the little pin, each time you make and break the connection, it arcs and burns part of the pin away until the pin is too short to make the connection any longer. [IMG]http://*****************.com/smile/emthup.gif[/IMG]
      020 trans info pages - www.BrokeVW.com
      NEW 0.7619 5th gears for the 020
      NEW 020 reverse gears
      '86 GTI 8V 2.0L -'88 Scirocco 16V - '10 F150 4x4

    12. Awaiting Email Confirmation diceman469's Avatar
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      08-23-2009 01:06 PM #11
      Sort of related to the original post....
      Do you have a P/N to the gasket that seals this kind of switch to the case? I could not find one and ended up just reusing it with some RTV.
      I hate doing it that way [IMG]http://*****************.com/smile/emthdown.gif[/IMG]

    13. Member Broke's Avatar
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      08-23-2009 01:22 PM #12
      Quote, originally posted by diceman469 »
      Do you have a P/N to the gasket that seals this kind of switch to the case? I could not find one and ended up just reusing it with some RTV.

      As far as I am aware the o-ring is included with the switch, already installed into the groove. There isn't any gasket or part number for the o-ring shown in etka, so I think it is part of the $35-$50 switch.
      020 trans info pages - www.BrokeVW.com
      NEW 0.7619 5th gears for the 020
      NEW 020 reverse gears
      '86 GTI 8V 2.0L -'88 Scirocco 16V - '10 F150 4x4

    14. 09-03-2009 02:22 PM #13
      Another sort of related to the original post...
      I installed a new tranny that has the 2-pin connector and now I know which 2 wires to use...THANKS! I went from the 4-pin to the 2-pin, so where do I get a connector for the 2-pin? And what do I do with the wires in slots #5 and #8?

    15. Member Broke's Avatar
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      09-03-2009 03:01 PM #14
      Quote, originally posted by MatthewR »
      where do I get a connector for the 2-pin?

      Junkyard or dealer. The plugs are used all over the car for many 2-wire sensors and devices, so snip one from a junkyard car, or the dealer can order new plugs with new terminals, you'll have to attach the wires to the metal pins, soldered ideally, then the pins and wires snap and lock into the plastic connector, and that's it.
      Quote, originally posted by MatthewR »
      And what do I do with the wires in slots #5 and #8?

      #8 should be one of the reverse light wires... but the other 2 non-used wires are for the upshift light. It turns the light off for 5th gear, so connecting them should simulate being in 5th, and will disable the upshift system, it'll think you're always in 5th.
      Check the wiring diagrams first to make sure I'm right though... wiring isn't my thing
      020 trans info pages - www.BrokeVW.com
      NEW 0.7619 5th gears for the 020
      NEW 020 reverse gears
      '86 GTI 8V 2.0L -'88 Scirocco 16V - '10 F150 4x4

    16. 09-03-2009 04:57 PM #15
      OOOPS! I meant to type #7. According to the wiring diagram (White w/ Green wire) that is indeed the upshift light. #5 slot is the ground (Brown wire). Thanks for the reply and the information.

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