From K9spud

Für die Deutsche FAQ VWCDPIC:FAQ German

Contents 1 Frequently Asked Questions 1.1 Where can I buy a VWCDPIC? I don't see an order button. 1.2 Why won't you sell me a fully assembled VWCDPIC? I heard that you used to... 1.3 I've heard that you need to have the head unit re-coded using a scan tool when installing a CD Changer. Will this be necessary to get my VWCDPIC to work? 1.4 I put together my VWCDPIC, plugged it in, and the head unit still says "No Changer." 1.5 I'm using an Apple iPod and I'm picking up background noise (such as engine rev's). 1.6 Do you have a version of the VWCDPIC that plugs directly into the rear of my head unit instead of the trunk CD Changer cable? 1.7 What's the part number for XXX connector? 1.8 It'd be great if the MP3 player could send the ID3 information to display at the head unit... Does the VWCDPIC let me display text on the head unit? 1.9 I've already got the CD Changer, but I want to add another audio input for my MP3 player. What do you suggest? 1.10 Is the VWCDPIC firmware upgradable? 1.11 I have an 'XYZ' brand automobile with their 'ABC' head unit. It also has a CD option, but the protocol is totally different from VW's. Do you have an adapter that will work for me?

Frequently Asked Questions

Where can I buy a VWCDPIC? I don't see an order button.

This is a Do It Yourself project. If you need a complete audio interface adapter with installation and technical support, talk to your local car audio shop. If you don't mind rolling up your sleeves to build a slick custom solution for yourself at minimal cost, this project is for you.

We've improved the VWCDPIC v3.x by designing it on top of our HOODMICRO PIC Programmer. This new design requires a few cheap parts, some cables, and a little soldering, but does not require any special tools beyond that because the PIC Programmer is built right in. The schematic diagrams and firmware you need are available in the Developer's Area.

Why won't you sell me a fully assembled VWCDPIC? I heard that you used to...

• The proprietary VW/Apple/etc connectors are prohibitively expensive when keeping large quantities in stock. Buy your own connector because you know that you are going to use it; we aren't willing to tie up money in expensive connectors that we may never sell or use.

• It's not very practical for us to spend time building and shipping heavy cables around, when you can make cables yourself cheaper.

• K9spud isn't big enough to provide lots of technical support beyond our Internet support forums. If you don't feel qualified to make a VWCDPIC yourself, find someone among your circle of friends who can help you. Surely someone you know has a soldering iron!

I've heard that you need to have the head unit re-coded using a scan tool when installing a CD Changer. Will this be necessary to get my VWCDPIC to work?

No. In theory, Volkswagen's head units could ignore a CD Changer based on the scan tool coding, but in practice we've never seen a head unit do so.

My 2001 New Beetle came with the VW CD Changer pre-installed by the VW dealership. When I finally got VAG-COM and read my head unit coding, it was coded to not have a CD Changer. Yet, the CD Changer worked fine all along! I changed the coding to say there is a CD Changer attached, but I did not notice any difference in operation whatsoever. If you want to play around with your head unit coding, Ross-Tech has the information you need at the very bottom of this page. Even freeware VAG-COM will let you read & modify the coding.

I put together my VWCDPIC, plugged it in, and the head unit still says "No Changer."

Make sure you made the head unit cable correctly. You should be able to use a voltmeter to detect power from the head unit when the head unit is turned on. If you have a 5V LED, you can check that the head unit is sending data on the DATA-OUT signal line. You should see the LED blink whenever entering CD mode on the head unit.

Make sure that you programmed your PIC chip with the right firmware. If you didn't program firmware into the PIC chip, it will not work! After programming, make sure you flip the switch to the EXEcute position so that the code can run.

If you've got the VWCDPIC properly attached to the car's CD changer plug, the PIC is programmed, powered, and running, but the head unit still acts like nothing is there, it is possible that the other end of the car's changer cable is plugged into the back of your head unit improperly. Since a real VW CD Changer would theoretically be installed at a VW dealership who could re-seat the cable if necessary, I don't think VW does a QA test on this cable connection at the factory. You need to pull your head unit and re-seat the blue mini-iso connector for the CD Changer.

Failing all of the above, you could try messing around with the head unit coding in VAG-COM to see if that helps. So far we've never heard from someone where this turned out to fix the problem. Please let us know if it does for you.

I'm using an Apple iPod and I'm picking up background noise (such as engine rev's).

The VW head unit needs a higher amplitude signal compared to your earphones. With a low voltage audio signal, you have to turn the volume up higher than normal at the head unit to hear it. This in turn amplifies small background noise picked up between the head unit and your player that you don't want amplified.

Try turning the volume of your player up higher and turning down the volume of your head unit accordingly. This will help reduce amplifying background noise.

A few folks with iPod's have found the Belkin iPod auto kit to be useful. Besides keeping your iPod fully charged, it has an audio amplifier that can be used to amplify the iPod's audio signal before it is sent to the head unit.

European iPods appearantly have a lower volume limit imposed by Apple's firmware. European users may find the goPod volume fix useful.

We also have a pre-amplifier add-on module that we've been playing with. You can find the schematics for it in the Developer's Area.

Do you have a version of the VWCDPIC that plugs directly into the rear of my head unit instead of the trunk CD Changer cable?

At the time of this writing, we haven't drawn up a pretty schematic diagram for making a head unit cable using the blue mini-iso connector, but it should be easy to do. Using the old VWCDPIC design, Reinhard Berghof soldered some wires to a blue mini-iso plug and got it to work fine.

Your car should already have a blue mini-iso connector hooked up to the back of the head unit, and cabling that runs all the way to the cd changer connector in the trunk. You could cut that cable and re-purpose the connector, or you could buy a new connector if you want to avoid permanently modifying your car.

The blue mini-iso connector is Volkswagen Part #4A0972643B (order one). You will also need to order the wire & pins to go inside the connector. They are Volkswagen Part #000979131A (order four). You should be able to buy these parts from any Volkswagen dealership or you can order them online from Impex Foreign Auto Parts.

Once you've got the connector, look at the head unit's pinouts for wiring. Make sure to connect the VWCDPIC GND pin to a good ground source (head unit chassis should work), as the blue mini-iso connection only provides the AGND signal. It will not work properly with only the AGND signal connected.

What's the part number for XXX connector?

Volkswagen doesn't make it easy to find out the correct part numbers for their spare parts, but over time we've collected all of the part numbers for the relevant VW cd changer related connectors. Check out this page for VW connector part numbers.

iPod dock connectors have traditionally been difficult to obtain, but it looks like things are getting better finally. iPodLinux.org has documentation about the dock pin outs and one of their forum members is distributing connectors in small quantities for hobbists.

It'd be great if the MP3 player could send the ID3 information to display at the head unit... Does the VWCDPIC let me display text on the head unit?

Unfortunately, no, there does not appear to be any way to send text data to the stock head unit display from the CD Changer data lines. All you will see when listening to the CD input is the display "CD 1 Tr 1."

When you press buttons on the head unit, the VWCDPIC will change the CD number and Track numbers to closely match what the real CD Changer would do, but this has no relation to the current song you are playing.

Not to be discouraged by a minor hurdle, Boris Tubak installed a Matrix Orbital LCD display in his GTI. You can see his notes in the forum.

I've already got the CD Changer, but I want to add another audio input for my MP3 player. What do you suggest?

If you've already got the CD Changer, you don't need a VWCDPIC to trick the head unit into thinking a CD Changer is installed; there really is a CD Changer installed!

What you need to do is splice into the audio signal wires and install a double pole, double throw switch to let you select between the CD Changer's audio and your MP3 player's audio. Shouldn't cost you more than $5 and some time with a soldering iron.

Cristiana at Cloud13.com has a very slick write up on how to modify the New Beetle in this fashion. The general concepts should still be helpful even if your car is a different body style.

However, if you've got lots of money to burn, SoundGate sells a canned solution for this purpose. Your pocket book will be set back about $150 though (at the time this was written). Ouch!

Is the VWCDPIC firmware upgradable?

Yes! Original VWCDPICs were difficult to FLASH upgrade because they required an additional PIC Programmer device to be temporarily connected to the surface mounted PIC chip, which was beyond most people's abilities. Today, however, the new VWCDPIC v3.x hardware design includes an integrated PIC programmer and a DIP socketed PIC chip that can be easily re-programmed without any special tools. Just hook the VWCDPIC v3.x control module to a PC with a serial port, and follow the FLASH upgrade programming procedure documented in the Developer's Area.

I have an 'XYZ' brand automobile with their 'ABC' head unit. It also has a CD option, but the protocol is totally different from VW's. Do you have an adapter that will work for me?

Nope, sorry. We can't magically make new head units work, but if you're a developer, you might be able to write some firmware for the PIC chip to communicate with your head unit. Mictronics has documentation for several different CD Changer protocols, and even has a few projects underway for Unilink protocol head units (Sony).