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    Thread: DIY - Installing a new brake light switch (without breaking it!)

    1. 12-19-2003 12:05 AM #1
      I had some free time and all the necessary pics, so I put this little DIY together. Hope it's useful to someone.

      The following outlines the procedure for installing a new brake light switch on a MKIV car. It is common for the switch to fail, resulting in either (1) no brake lights when the brake pedal is depressed OR (2) the brakes lights staying on constantly, regardless of brake pedal position AND (3) the cruise control not working. In cars with automatic transmissions, a failed brake light switch will also prevent the car from being shifted out of park since the brake pedal needs to be depressed for this to occur and the car/tranny does not know the brake pedal is being depressed.
      The procedure below applies to the most recent 4-pin brake light switches with the following part#s - 1J0 945 511 B, 1J0 945 511 C and 1J0 945 511 D (the most recent version - if you buy a new switch it will almost certainly be the 'D' version since it supercedes all previous versions). If you have an older style of brake light switch with part# 1J0 945 511 A, then the special installation procedure given below does not apply. See the procedure given at the very end of this DIY for installing this switch.
      A new brake light switch (1J0 945 511 D) should cost around $10-15 at your local dealer or slightly less on the Internet (http://www.worldimpex.com, http://www.1stvwparts.com).
      No special tools are needed to perform the below procedure (assuming that you have already accessed the switch by removing the required trim pieces as described in this DIY - Removing Interior Parts II).

      __________________________________________________ __________________
      The picture below shows an example of the most recent style brake light switch (either a 'B', 'C' or 'D' switch). If the brake light switch that you want to install does not look like this (i.e., it is an 'A' switch), the proceed directly to the section at the end of this DIY entitled "Installing The Switch ('A' Version)". If you purchase a new switch, then it will most likely be the most recent version, the 'D' switch, and the following installation procedure will apply to you.

      There have been numerous posts on the Vortex about failed brake light switches and a number of different installation procedures have been suggested. Unfortunately, all of them are either incomplete or just plain wrong, and will lead to the switch breaking when being installed. This is probably why many people have posted that it took 3-4 tries (and a new switch with each) to get the switch installed properly. Contrary to what some Vortexers have posted, you CAN move the plunger in and out before the switch is installed without the switch breaking. It actually needs to be able to move when you install it - the plunger on the switch is self-adjusting and will compress a good bit when installed. Also, the switch does not need to be installed with the ignition on and should NEVER be rotated into the locked position with the brake pedal depressed (this is the critical flaw in the previously posted procedures).
      After breaking a new switch myself while trying to install it, I decided to disassemble the switch to figure out exactly how the internal mechanism works and why it fails if the switch is installed incorrectly. What I discovered is that the rotating of the switch into place not only secures it to its bracket, it also rotates the internal mechanism into position and locks the plunger length. This is shown in the pictures below. The picture on the left shows the switch in its unlocked (unrotated) state. The two tabs that secure the switch in its bracket are indicated by the blue arrows. Note that there is a third tab (red arrow) underneath one of the tabs. When the switch is inserted into the hole in its bracket and rotated into position, the third tab is pinned against the side of the bracket hole, causing the switch internals to rotate inside of its housing (the internals actually stay put, it's the outer housing that rotates). The picture on the right shows the switch in the locked (rotated) state. Note that the third tab is not underneath one of the other two tabs anymore and is now visible.

      Because of the way that VW designed the switch, part of the internal mechanism will break off if the switch is rotated into position WITHOUT the plunger fully compressed against its spring tension. This is why many people, including dealers, destroy switches when installing them - the switches don't come with installation instructions and people don't understand how the internal mechanism works. Therefore, when installing a new switch, it is critical that the plunger be compressed against its spring tension or the switch will break and you'll need to buy a new one. It is also necessary to set the correct plunger length so that the brake lights will come on with minimal movement of the brake pedal. Fortunately, the plunger is self-adjusting. The plunger is ribbed on the inside of the switch and will 'ratchet' down to its proper length during installation. The rotation of the switch during installation will then lock this length in.
      Now that I've probably confused everyone, it's time for the installation procedure. This procedure is actually very simple, but must be followed exactly or the switch will break.

      INSTALLING THE SWITCH ('B', 'C' or 'D' versions)
      1. Before attempting to install a new brake light switch, first make sure that the switch is in its unlocked state (as described above) AND the plunger is fully extended (approx. 1"). A newly purchased switch should be in this condition and nothing further should need to be done to prepare it for installation - go directly to step 2. If the switch appears to be in its locked state OR the plunger appears to be compressed, then these need to be corrected before installing the switch. To unlock the switch, press the plunger in completely and then rotate the switch housing while holding the plunger in. (Similar to during switch installation, if the plunger is not held in against its spring tension while doing this the internal mechanism will be broken). If the plunger is not fully extended, make sure the switch is in its unlocked state and then pull the plunger out all the way, as shown below. You should hear a clicking noise from the ratchet mechanism inside as it's extended.

      2. The bracket that holds the brake light switch is indicated by the yellow arrow in the picture below. Note that the hole in the bracket is not symmetrical and as a result, the switch can only be inserted one way. The hole is diamond-shaped on top (red arrow) and square on the bottom (blue arrow).

      3. Push down the brake pedal as far as it will go. If it does not go down enough, start the car temporarily to loosen the brake pedal and then turn the car off.
      4. Insert the new switch into the bracket. For the tabs to line up, the square wiring harness portion of the switch needs to be on top and approximately 35-45° counter-clockwise from horizontal, as indicated by the yellow arrow in the picture below. (Note: The picture shows the brake pedal NOT depressed since I needed both hands to take the picture. It should be fully depressed at this point.)

      5. While holding the switch in place (DO NOT LET IT PUSH BACKWARDS - THIS IS CRITICAL), release the brake pedal and pull it back slowly as far as it will go (until it hits the stop), as indicated by the red arrow in the picture above. You should hear the plunger click as it compresses. This procedure sets the correct length for the switch plunger.
      6. While still holding the new switch fully against the bracket, rotate the wiring harness portion of the switch 35-45° clockwise until it clicks into place, as shown in the picture below.

      7. Connect the wiring harness to the switch, as shown in the picture below. The switch has been installed correctly and should now work fine.

      WARNING: If at any time during steps 5 and 6 the switch backs away from the bracket (even a little bit), DO NOT ATTEMPT TO ROTATE THE SWITCH INTO POSITION!!! It will break. Do not just push the switch back against the bracket and then rotate it. YOU MUST REMOVE THE SWITCH, PULL THE PLUNGER OUT ALL THE WAY AND START FROM THE TOP! This is due to the fact that the plunger compresses against its spring tension FIRST and then shortens in length by the ratcheting mechanism. Not doing the process in one stage may cause the plunger to not be fully compressed against its spring tension (i.e., the plunger will move inwards by permanently shortening instead) which could lead to the internal mechanism being broken when the switch is rotated into position.

      Note: Because of the poor (and IMO unnecessary) design of the internal mechanism of the switch, it may still be possible to break the internal mechanism of the switch even if you install it correctly. This could happen if the switch doesn't compress against spring tension first and instead shortens the plunger length first. If this occurs, the internal mechanism may break when the switch is rotated. If this happens, then you got a lemon switch. Unfortunately, there's probably not much that can be done except to buy another new switch since the dealer will most likely assume that you installed it incorrectly.

      INSTALLING THE SWITCH ('A' version)
      Installing the original 'A' version of the brake light switch (shown in the picture below - note that the body (red arrow) and plunger (yellow arrow) are different) is much simpler than installing the later 'B', 'C' or 'D' switches since the 'A' switch does not have the crazy self-adjusting/locking internal mechanism that the 'B', 'C' and 'D' switches have. To install an 'A' switch, pull the plunger out completely, press down the brake pedal fully, insert the switch into the hole in the bracket, turn it 90° clockwise to secure it and then pull the brake pedal back fully (slowly) to set the correct plunger length. That's it.

      I wonder why VW switched to the more complicated design. All it's done is cause us owners (and dealers) a lot of headaches!

      Let me know if you have any questions.
      As always, do this procedure at your own risk. I am not responsible for any mistakes in the above procedure or those that you make while performing it.

      Modified by VgRt6 at 12:44 AM 6-25-2006

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    3. 12-19-2003 01:01 AM #2
      You just saved a lot of people fees from the dealership. Thanks for doing this!

    4. Geriatric Member Dan Halen's Avatar
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      12-19-2003 01:26 AM #3
      Yet another beautiful VgRt6 write-up... nicely done!
      Ride In: 2008 Signal Green Cayman S Sport 378/700 .:. 2006 Plat Grey GLI .:. 2008 Sage Green Rabbit
      Ride On: 2010 Trek 2.1 .:. 2011 Fisher Cobia

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    6. 12-19-2003 09:35 AM #4
      Morning bump for those who missed it last night. [IMG]http://*****************.com/smile/emthup.gif[/IMG]

    7. Moderator rs4-380's Avatar
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      Dec 12th, 2000
      VWs & Audis
      12-19-2003 09:42 AM #5
      Hah, the A version is what was (is) used on A2's! Worked fine according to my experience. and Was much easier to replace than the newfangled ones.

    8. 12-19-2003 09:53 AM #6
      Quote, originally posted by rs4-380 »
      Hah, the A version is what was (is) used on A2's! Worked fine according to my experience. and Was much easier to replace than the newfangled ones.

      It's also what came with my '99.5 MKIV. My sister's '00 had a 'B' though. Hers went bad last weekend and I replaced it with a 'D'. I ended up breaking the new switch when installing it because I followed someone else's directions in another thread. I didn't want to have to buy another switch, so I took apart both the 'B' and 'D' switches, figured out how they worked internally and then built a working switch using parts from the two broken ones. Worked like a charm!

    9. Member turborave's Avatar
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      Jun 13th, 2001
      Clarksburg, MD
      2001 Jetta GLS, 2012 Routan SE
      12-19-2003 09:58 AM #7
      Quote, originally posted by VgRt6 »
      It's also what came with my '99.5 MKIV. My sister's '00 had a 'B' though. Hers went bad last weekend and I replaced it with a 'D'. I ended up breaking the new switch when installing it because I followed someone else's directions in another thread. I didn't want to have to buy another switch, so I took apart both the 'B' and 'D' switches, figured out how they worked internally and then built a working switch using parts from the two broken ones. Worked like a charm!

      i had to do the exact same thing a while ago on a friends GTI.. i had to take 2 switches and combine them in to one working switch..

    10. Geriatric Member CapeGLS's Avatar
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      Aug 2nd, 2002
      01 Golf GLS 1.8T, 11 Jetta SE, 11JSW 2.5SE (Wifes)
      12-19-2003 10:02 AM #8
      Quote, originally posted by BRM10984 »
      Yet another beautiful VgRt6 write-up... nicely done!

      Bump to that, He should be the OFFICIAL DIY poster...
      ET Feature Car 1/08|Forgeline Wheels|WRDusa.com|

    11. Member Knighthammer's Avatar
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      MKV R32, 09 Tiguan
      12-19-2003 11:40 AM #9
      Quote, originally posted by CapeGLS »
      Bump to that, He should be the OFFICIAL DIY poster...

      I'll second that - good write up!

    12. 12-19-2003 07:11 PM #10
      Bump for the evening crowd. [IMG]http://*****************.com/smile/emthup.gif[/IMG]

    13. Member msuperbauer's Avatar
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      MKV GTI
      12-20-2003 12:15 PM #11

    14. 01-06-2004 08:07 AM #12
      Thanks for a great write up; I went to the dealership yesterday; (before reading this) and broke two switches at the dealership. The guy at the parts counter got fussy with me and I left. So now I will go to another dealer today to try and put one of these in with your instuctions. Wish me luck. I hate these little things already. You would think something as important as brake lights would earn requirement for a more rigid part.

    15. 01-07-2004 12:06 AM #13
      thanks to this great write up i now have brakelights again [IMG]http://*****************.com/smile/emthup.gif[/IMG]

    16. 01-07-2004 12:50 AM #14
      Glad it worked out for you.
      I wonder how much $$$ VW makes off of selling 3-4 switches to everyone!

    17. 01-07-2004 12:53 AM #15
      he strikes again!!! Gary=Vortexer of the year...easily [IMG]http://*****************.com/smile/emthup.gif[/IMG] [IMG]http://*****************.com/smile/emthup.gif[/IMG]

    18. 01-07-2004 12:59 AM #16
      Thanks Sully, but that was from LAST year. Wait til you see what I have planned for this year!

    19. 02-02-2004 11:49 PM #17
      VgRt6....you're the man. My cruise has been busted for like 8 months and all it tooks was 30 minutes and 10 bucks to fix...thanks for the great DIY

    20. 02-27-2004 05:41 PM #18
      hi everyone - this has happened to me i believe - i couldnt get my car out of park - took about 20 pushes and jiggling - no lights on the back - guy who i asked said they came on intermittently
      how hard is this fix? im not that great with this stuff - i was able to change out my backup light in the trunk
      any help is appreciated as i am going to go to the dealer tomm morning if all else fails
      thank you

    21. Member Schmitty's Avatar
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      Aug 27th, 2002
      Madison, WI
      MKIV Jetta, Monster 800
      02-27-2004 06:43 PM #19
      I just got mine replaced today under warranty..along with the front O2 sensor and had an appointment made to replace the belt tensioner.
      Man, I'm just waiting for the day when this thing falls apart when I hit the unlock button with the FOB...

    22. 04-03-2004 01:39 PM #20
      Luckily I found this site after destroying only one new switch. I just successfully installed the second one after following your instructions. I wish the dealer would have warned me about this procedure when I bought the new switch. Thanks for the info.

    23. 04-19-2004 09:32 PM #21
      Man, I just want to say thank you. You just saved me a great deal of aggrivation, money and time. If I had taken this to the dealer, it would have taken them about 4 hours and they would've charged me for as much. Thanks again.

    24. Senior Member JettaGT8V80's Avatar
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      Jun 11th, 2003
      Waltham , Ma
      2014 W212 sport
      04-19-2004 09:49 PM #22
      my sister jsut brought her car in for thsi reason but they dont have the part so now the part wont be in till wednesday but now i can save her the hassle fo bringing the car in and i can do it myself thank you so much for thsi DIY [IMG]http://*****************.com/smile/emthup.gif[/IMG] [IMG]http://*****************.com/smile/emthup.gif[/IMG] [IMG]http://*****************.com/smile/emthup.gif[/IMG] [IMG]http://*****************.com/smile/emthup.gif[/IMG] [IMG]http://*****************.com/smile/emthup.gif[/IMG] [IMG]http://*****************.com/smile/emthup.gif[/IMG]

    25. Member Buran's Avatar
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      Brentwood, MO
      2017 Honda CR-V Touring
      05-10-2004 06:40 PM #23
      Is anyone else finding the images are refusing to load? I'd like to make a PDF of this page but without the images, it's not too useful.

    26. Member Murphy's Avatar
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      Jul 27th, 2003
      Oil Burner
      05-10-2004 07:23 PM #24
      there is a recall on these switches for certain models.
      I'm on my feet, I'm on the floor, I'm good to go.

    27. Member vasillalov's Avatar
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      Chicago, IL
      2008 BMW 335i, 2010 Rav4 V6 Ltd.
      05-10-2004 07:29 PM #25
      VWOA issued a new recall for all 99-02 Jettas with factory cruise control!
      Quote Originally Posted by MAG58 View Post
      Please consider your audience before saying something sensible. 80% of TCL drivers were actually banned from Formula 1 for being too fast.
      A turbocharger is a device in where exhaust gases go in, witchcraft happens, and then you go faster.

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