Ok, so this is one of those projects that I have been going to do forever. About 1.5 years ago I got a Zen Touch 20Gb, and then this last Spring I bought a 97 Pontiac Grand Prix GT.
One of the first things I did was bought a dub cable so I could connect my Touch through the aux plug on my head unit. This works great and I have only used cd's on a couple occasions. One problem with this, as you can imagine, is that it can be a bit of a distraction from the road.
Well, my GP came with really cool controls built into the steering wheel that controlled the factory stereo. Too bad the controls don't work with aftermarket HU's without a spendy adapter. Even if I did get this adapter, it wouldn't be very useful in my situation (the only thing I actually use on the HU is the volume, since I am using my Touch).
I figured, why not just reengineer the circuit in the controls to work with my Touch? Sounds like a fun project.
Well, after a few months of thinking and researching off and on, I decided to start major work. First off, I used a thread (
link) I came across as a starting point for building a prototype. The guys on this thread had done alot of work mapping the circuit in the original Touch remotes, but there were still some unknown functions and values, so I picked up where they left off. After I was confident that I had a solid understanding of the circuit, I started working on a prototype.
On a side note, I love how these projects make a nice excuse to buy a new soldering gun, multimeter, and other various toys.
So here is a pic of my original working prototype. All of the functions worked as planned. I was very happy to have this work.
As you can see, the circuit is a pretty straight forward variable resistance circuit.
Next I did some research on exactly how the controls in my steering wheel worked. I was happy to find that they worked on the same variable resistance principle.
The only problem was that the order of the controls and the resistances were very different. As you can see from the following pic, the buttons are arranged in a specific way. This would make it a problem to just change the resistors, since then my play and volume up would be on opposite sides of a rocker switch.
In order to make this work as I wanted, I needed to do some re-engineering of the control boards. Thankfully, my prototype needed few alterations. In case someone needs these values years from now when the picture links are dead (anyone who has researched with forums can understand), here are the values for each function (can vary a few 1000 olms either way):
- 660k = Bridge
10k = Play/Pause/Power on
32k = Next/FF
54k = Previous/Rew
76k = Stop/Power Off
144k = Volume Up
226k = Volume Down
There were some more fuctions such as toggle equalizer off/on, but on hold it started the voice recorder, which would lock up since this is not a real remote with a mic.
I will try to get the page with all my work for the schematics of the board rewiring scanned in and posted, but for now, all I have is this pic of the finished board. Take note of the new resistors and the white wire on the right board. The back of the right board has about 5 other wire bridges.
Upon testing of the installed circuit, I notices that the signal wasn't getting from the steering wheel to the wires in the column. Turns out that the clock spring is faulty. For all the work that I have put into this, I am not stopping because of some bad part.
I am taking the car in this week to have that piece replaced (wish I had the time to do it myself).
My classes start again this week (I am a freshman at NDSU for computer sci.), so I will see if I can get enough free time to finish this in the next couple weeks. As soon as I have more pics I will post them and some explanations.
As you can see, all that needs to be done is to remove the metal shell from the end of a usb connector, and then carve down the plastic down to the pins on the sides and end. You will also have to carve some off the plastic on the back to get it to fit in the connector port on the Touch.
One side also has to be carved down in order for the cable and the audio jack to be able to physically fit side by side. I then just glued the audio cable and the usb cable together. Later I will be putting some heat shrink wrapping to make the whole thing look a little better.
, lets see what you can do once u get a pc fitted in your car.
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