Volkswagen Passat Forum banner

1 - 20 of 134 Posts

2,505 Posts
Discussion Starter #1
Well guys... I said I was gonna follow up on my quest to make this tool and here it is! IT WORKED!!!

And I took some photos along the way to share with you guys my little project in case some of you are interested in making one also. It's SUPER EASY... if you have the right tools and patience.

Kudos to Jeff at Planetfall for sharing this great stuff. Thanks!

So here it is:

PLEASE NOTE!! If you do attempt this project, PLEASE PLEASE READ all caution labels on anything that you buy (really it's the ferric chloride.) Take it slow and use safety devices (ie... mask, goggles, gloves, etc.) To give you an idea of what skill level it takes to do this, I'll use me as an example. I'm not an Electrical Engineer. I'm a Computer Programmer with an MBA and a tv broadcast journalism background. I feel that if you can read and follow directions (along with some common sense), you should do just fine and be able to complete this project.

Now for the disclaimer:

You will be attempting this project on your own and will accept full liability and responsibility for what ever happens should something go wrong. I take no responsibility for any mishaps that should come up while you work on this project and while you use it to work on your car. Basically, you do this at your own risk.

So what does this device do? What's its purpose? Why would someone want one of these VAG-COM devices?

The answer is this: In addition to the tweaks (change your transmission to sport mode, change your auto-door lock, tweak your stereo, etc) that you can do to your car, VAG-COM allows you to read the codes that your car throws in the event something is wrong (ie... your car runs sluggish or Check Engine Light is on, etc.. ). With the code and the bentley (or someone here on the forum can help you) you would be able to pinpoint exactly what's wrong with your car before you even pull into the dealership. If it's a simple fix, you can even do it yourself and save yourself $$ from having it serviced at the dealer (if your car is out of warranty).

Also... with the pluggins supplied by ROSS-TECH, you can also use VAG-SCOPE to log data about the performance of your engine.


LEVEL OF PROJECT DIFFICULTY (SCALE OF 1 TO 10 with 10 being the hardest): 4.5

TIME FOR COMPLETING PROJECT: About 1.0 to 2.0 hours (maybe a little longer) depending on skill level

COST OF PROJECT: Less than $8.00 if you already have the tools and supplies

Print out the schematic from Jeff's's website on transparancy. Print out the instructions. All the parts necessary for this project is also at this website.

Some have been confused about which side goes to which on the schematics. Here's an pic of the layout which I modified to help give reference:

* Click here for the parts list and schematics
* Click here for the guide written by Jeff.
* Click here for the PDF version of the board layout. Print this on transparancy

Obtain all the parts necessary for this little project (transistors, copper boards, switches, ferric chloride, etc). If you order from, you won't find Part#2N3904-ND (NPN SML SIG G.P. AMP&SWITCH TO92 ) but there is an alternative that you can use that will work (which is what I used!): Part#497-2395-ND (TRANSISTOR NPN 60V 200MA TO-92).

- Dremel tool or something similar. I used a cheap $2.99 rotary tool which I got from a long time ago from
- Soldering Iron ($2.99 from Fry's)
- Solder (Get the really thin one)
- Rubber Gloves
- Handy Helper (Look in the pictures below. It's this metal thing with arms on it). Helps to hold your board while you work ($7.99 from Radioshack). I noticed that Harbor Frieght also sells this same tool for half the price of what I paid for!
- Fun Hat
- Digital Multimeter is helpful here to test your leads. Got it for $2.99 from
- Nail Polish Remover

- Type Cable 7 (Is what connects from the car to this device). This is the most expensive piece. You can build your own or you can buy one from Multiplex Engineering for I think $20 or so.
- Serial Cable (Is what connects from the device to your computer). This should be relatively cheap, about $5 or so, maybe less depending on where you get it. I got mine from Fry's Electronics.

- VAG-COM (Registered version $99 will offer full functionality of the software... or shareware version which allows you to do most things.) Whether which one is right for you (Registered versus Shareware) depends on your needs. If you spend a ton of hours on your car and you do EVERYTHING on your own, then it's best to get the registered version. Now if you only play with your car once in a while and want to simply change a few minor stuff and be able to read codes, then the shareware version will probably meet your needs.
While you're there... I'd recommend downloading the "55 page printable manual version 311.2" and read through it to understand how to use VAG-COM. Very easy read.

Start with a bare copper-clad board. I bought the copper board from Fry's Electronics for like $2.50 or something like that. It's big enough to make three of these boards. Clean the board well using rubbing alcohol to get rid of any dirt, grease, or any buidup that's on the board. Print out the schematic on a transparancy per the instructions and it looks like the picture below. Under no circumstances should you attemp to enlarge the print or reduce the print since some of the components are true to size, meaning if you enlarge it or shrink the print, your components won't fit later.

I found it easier to fold the transparancy in half and slide the copper clad
in between to prep it for ironing.

Iron the heck out of it for about 5 min - 10 min at about 85% high heat.
Don't let the transparancy melt though!! I'd recommend making several of these boards in case you mess up since it's really cheap (like pennies). The transparency will get hot... so take care not to burn yourself.

Let it cool in a sink full of cold water for a few minutes.

Slowly and carefully peel back the transparancy and you should have your copper clad board with the toner on it!! Most of the toner should be transferred to the board. If not, and there are exposed copper where there shouldn't be, you can simply use a super fine tip permanent pen (available at your local office supply store. get the finest tip you can fine) by sharpee to fix it by drawing on it and connecting the lines. However if there's too much toner missing (It happened to me the 1st time), simply use nail polish remover to remove the toner, print out another artwork, and go iron the print back on again.

Here's a pic of my dog (Roxie) who was with me in the build process.

Get a "ZipLock" plastic container (to be used for this AND NEVER USED FOR FOOD EVER AGAIN!!!), pour about a 1/4 cup of ferric chloride (I got from Fry's Electronics) in it. Mix with about 1/4 cup of hot (but not boiling hot) water (Basically a 50/50 mix). (Reason for heat is to speed up the etching process, otherwise it can take hours!!)

PUT ON A PAIR OF RUBBER GLOVES FOR THIS and use a mask to avoid inhaling the fumes! Better be safe than sorry. Place your copperboard with the artwork on it into the plastic container. Close the lid and agitate the heck out of it for a good 5 min to 10 min or until all the copper is gone. If in the event your mixture has gotten cold and your etching process is taking longer than 10 minutes, have no fear. Do this to get the process going again. Fill your sink with steaming hot water. Place the ziploc container with the ferric chloride and copper board in it in the sink. Agitate. The warm/hot water in the sink will get the ferric chloride going again. Check every 5 mins or so to check the progress of your board.

Once the last step is done, wash the board thoroughly with cold water to clean it. Keep the cold water facet running for a few minutes when you're done to flush out the ferric chloride. Wash everything well including the gloves, the sink counter, etc.

Use nail polish remover to remove the toner that's covering what's left of the copper. It should look like the picture below after you're done cleaning. All the copper lines should be there (I would compare your result with the schematic to make sure it's all there). If not, you can either use a copper pen to fix it or just start all over again. If there are copper leads that are fused (and it's not suppose to be), I'd recommend using a sanding drill to sand them apart or simply start all over.

Here's a comparison of one that has toner on it and one that doesn't.

I dont' have a picture here of it... but you want to get a dremel tool or
something similar with a small bit to start drilling tiny little holes on it
where the components are suppose to be. Don't over do it with the holes. Just make a hole large enough for the leads to fit. If you over do it, you'll drill away the copper plating (which is what the solder sticks to). Without copper plating, the solder won't stick! In the picture below, you can see that I already did the drilling.

This is where the challenging part is.... soldering. Take your sweet time and do it right. Mistakes are not forgiving since fixing them poses a challenge. Solder sticks very nicely to clean copper. So if you accidentially solder two copper leads together... try and fix it. But if there's just too much damage, start over. Patience is key here.

Here's progress...

More progress... almost done...

Very close...

And ta da!! All done! Now download the shareware version from (if you don't want to pay $99 for the registered version), load it up, hook the baby up with a Cable 7 and serial cable, and you're set to go!!

Here are some photos of the connection. My car is an Audi A6 2.7 so the OBDII connector is located on the lower left hand side of the steering column. This is what the connector looks like:

Now it's connected:

The full connection:

A pic of the computer screen which show information about my car:

---- Edit with more info ----

I was able to read all my codes. Plus I was able to recode. First thing I did, recode my transmission to sport mode.

I'll take some additional photos and post it on here tonight or sometime soon. (ie.. setups, hookups, etc).

Keep checking back for updates if you're interested!

612 Posts
Greatest Post Ever!

1,512 Posts
amazing! This will be a fun project.

At least, one I bought comes with a cover. :wink:

55 Posts
Wow! That looks GREAT!!! What would you charge to demo the process again and send me the comleted device??? I am soldering impaired. :poke:


0 Posts
am i the only one who knows nothing a diodes and soldering and schematics, im truely amazed! :shock:

2,505 Posts
Discussion Starter #14
The whole project will probably take about 1 hour to complete (It took me about 2 because I was taking it SUPER SLOW and running around finding my tools that I need.

I have to admit, it's REALLY fun and FAIRLY EASY!! On a scale of 1 to 10 on difficulty with 10 being the hardest, I'd say it's about a 4 or a 5. The savings is there (you can figure out the math). All the parts cost less than $10. Shareware of the software, FREE.

To demo again and sell it? I thought about it. Probably something like $20 shipped to cover the parts, my time, packaging and shipping. I have one other board left that I haven't started drilling. It's a complete print. Just needs drilling, and assembly. Oh yea... I have all the parts too!

Yes there is an alternative that you can use that will work (which is what I used!): Part#497-2395-ND from The description is: TRANSISTOR NPN 60V 200MA TO-92

Group Buy? Oooo... this one should be real cheap since ordering these components in quantity will GREATLY drive the price down! Now you're talking!

4,876 Posts
Thanks for the reply. I will get on that part. Order maybe as soon as today. Going to talk to one of me EE professors for some tools and see if he will assist me. Never really soldered before.

As for the price, still got to pay for the cable too. The cable connecting the tool to your ride is about 20 bucks. Just an FYI.

I was reading on the ROSS-Tech site, and they have this little write up why you should buy the VAGCOM and not this OBDII stuff.. the OBDII tool didnt recognize any errors on a GTI but the VAGCOM ead 10 faults.

True? Any disadvantage from this homemade tool and the VAGCOM in terms of recognizing faults.?

Thanks ya'll.


2,505 Posts
Discussion Starter #16

I was reading the info on the link you provided. VAGCOM and OBDII are both software. VAGCOM I believe is made by Ross-Tech. Then there are other OBDII software that other companies make.

What Ross-Tech is saying is that THEIR software is able to read fault codes that other OBDII software can't (Go back to the link you provided and notice the screen shots are different between VAG-COM and OBDII generics).

This homemade VAG-COM tool allows you to connect to the car and make use of the VAG-COM sofware without paying some $70 or $80 for the cable. So being that the home-made tool is using the VAG-COM software from Ross-Tech, I imagine it should operate as advertised (less the registered VAG-COM software).

Hope that helps!! :thumbup:


541 Posts
This design works pretty good. I've scanned at least 20 some cars with it over the last 3 years.

You can also do it without all the etching. Just use jumper wire instead of etching it all if want. However you'll find the cost of the parts you only save like $20. You still have to buy the software.
1 - 20 of 134 Posts
About this Discussion
133 Replies
60 Participants
Volkswagen Passat Forum
Passatworld is a forum dedicated to Volkswagen Passat enthusiasts to discuss mods, Quattro, Turbo Diesel, reviews and more!
Full Forum Listing