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I am reaching out to anybody with a C5 Corvette in the Toronto Ontario area equipped with the original sound system.
This is all about the CD changer, specifically the Delco Electronics P# 16199553, connected to the radio on the slow E&C data line.
This was GM's 12 disk CD changer used in most Cadillacs ('96-'02), the C5 Corvette, some of the (upper models) Buicks, Oldsmobile and Pontiacs. It was also equipped on some of the fancier trim trucks.
There is also a 6 disk version (available after '98) and the two are fully interchangeable.
In the last 3 years I am working on a project to build a replacement that allows:
1. Solid state memory (microSD & USB Flash Drive) supporting mp3/wav/wma;
2. Bluetooth (including controls next/pervious from the radio buttons) ;
3. Auxiliary input;
4. Plug and play, no wiring/programming required;
5. Work as a replacement of the OEM CD Changer or as add on (tandem).
I am in the final stage of the development, past the working prototype stage.
I have access to multiple Cadillacs, BOSE or base sound system, where is currently being tested (long term reliability testing).
I am looking for anybody with a C5 corvette in the Toronto (or GTA) area that is willing to volunteer his/her C5 for 10 min - 20 min to test the CD Changer replacement on this platform. I can demonstrate the functionality in a Cadillac, in case there are any doubts or worries about causing harm to the Corvette.
In case you are curious, this can play up to 1188 audio file from a SD Card and another 1188 from a USB stick. There is a slot for a microSD card and a USB port. The files are accessible from the OEM radio as "disks" (a.k.a. folder) from 1 to 12 and "tracks" (a.k.a files) from 1 to 99. Although the hardware can support significantly more files, unfortunately this is a limitation of the E&C protocol.
One of the "disks" can be substituted with a Bluetooth receiver and any Bluetooth enabled device (phone, tablet, laptop...) can stream to the car audio system. The Next(>/Previous(< buttons on the radio and steering wheel (I know, not equipped on C5) will allow changing the songs (hands free operation).
Finally, if you still have an iPod or you really want to have hard wired Aux Input, that is also supported.
Because is not clear to me if all C5 were pre-wired with the CD changer harness (is located in the trunk) I would prefer somebody with a C5 already equipped with the CD Changer. This is the connector at the end of the CD Changer harness.
Thank you for your reply.
The CD Changer replacement works exactly like the original CD Changer, as far as the Radio is concerned.
You are able to select disks from 1 to 12 and within each disk one of the available track and off course you can navigate "<" or ">" between tracks.
The difference is that instead of actual CD magazine, is a SD Card (or a USB Flash Disk), the "disks" are actually folders (folder 01 = "disk 1"...folder 12 is "disk 12"). And since memory size is no concern, you can have up to 99 "tracks" in each "disk".
One of the "disks" (specifically no 12) can be substitute with a Bluetooth receiver. Meaning that instead of playing mp3 files from the SD Card/USB Flash Disk, you are streaming from a phone (or whatever Bluetooth is connected to the CD Changer replacement). The "<", ">" buttons on the radio can be used to navigate trough the playlist (let's say you have a playlist on Spotify, you can use your radio buttons to navigate to next/previous).
Or you can have, instead of Bluetooth, Aux Input, as soon as you connect the Aux Jack in, it will mute the Bluetooth and replace it with the Aux Input signal.
That being said, the control of the antenna is in the radio firmware, and there is no instruction on the E&C data line (the one I am using to communicate with the radio) to control the antenna position. If the radio keeps the antenna up while selected source is [CD Changer], it will do so while working with the CD Changer replacement. The firmware in the radio is the property of the manufacturer and is not public, if I will need to make any changes to it, I would need to rewrite the whole firmware myself. Of course there are much easier ways to control the antenna by simply bypassing the antenna output of the radio, but that would require some re-wiring, my goal with the CD Changer replacement is plug and play (similar effort as, for example, plugging into the power port a phone charger).
Pardon my ignorance, I am very familiar with the Cadillac, and only assume what would be on a Corvette, hence reaching out for somebody with a C4 Corvette,
So indeed in the Cadillacs, after '98 (or '00 depending on the model), the power mast (the proper terminology for Cadillac, possibly Corvette to) was replaced with a windshield strip. I call it cost cutting, somebody else can call it progress.
The same exact radio can be used in either case, the radio has one pin that is labeled "antenna signal", this pin (at least in the Cadillac radios) is on as long as the radio in on, regardless of the selected source: radio (yes needed), tape, CD, CD Changer (no, not needed).
The cars with the windshield integrated antenna have an "antenna module" (let's just call it signal booster/amplifier) that is powered from the "antenna signal" pin. Basically the cars with the power mast will use this signal to lift/lower the antenna mast, while the cars with the windshield integrated antenna will be using the same signal to power the "antenna module", but at the end of the day is the same exact radio used in both cases.
Last edited by 1KRetrofit; Apr 7, 2025 at 12:16 PM.
Thank you for your reply.
The CD Changer replacement works exactly like the original CD Changer, as far as the Radio is concerned.
You are able to select disks from 1 to 12 and within each disk one of the available track and off course you can navigate "<" or ">" between tracks.
The difference is that instead of actual CD magazine, is a SD Card (or a USB Flash Disk), the "disks" are actually folders (folder 01 = "disk 1"...folder 12 is "disk 12"). And since memory size is no concern, you can have up to 99 "tracks" in each "disk".
One of the "disks" (specifically no 12) can be substitute with a Bluetooth receiver. Meaning that instead of playing mp3 files from the SD Card/USB Flash Disk, you are streaming from a phone (or whatever Bluetooth is connected to the CD Changer replacement). The "<", ">" buttons on the radio can be used to navigate trough the playlist (let's say you have a playlist on Spotify, you can use your radio buttons to navigate to next/previous).
Or you can have, instead of Bluetooth, Aux Input, as soon as you connect the Aux Jack in, it will mute the Bluetooth and replace it with the Aux Input signal.
That being said, the control of the antenna is in the radio firmware, and there is no instruction on the E&C data line (the one I am using to communicate with the radio) to control the antenna position. If the radio keeps the antenna up while selected source is [CD Changer], it will do so while working with the CD Changer replacement. The firmware in the radio is the property of the manufacturer and is not public, if I will need to make any changes to it, I would need to rewrite the whole firmware myself. Of course there are much easier ways to control the antenna by simply bypassing the antenna output of the radio, but that would require some re-wiring, my goal with the CD Changer replacement is plug and play (similar effort as, for example, plugging into the power port a phone charger).
Pardon my ignorance, I am very familiar with the Cadillac, and only assume what would be on a Corvette, hence reaching out for somebody with a C4 Corvette,
So indeed in the Cadillacs, after '98 (or '00 depending on the model), the power mast (the proper terminology for Cadillac, possibly Corvette to) was replaced with a windshield strip. I call it cost cutting, somebody else can call it progress.
great idea, but other than the SD card, how is it different than discount car stereo's harness?
I was no aware of this product, I did quickly checked the link you provided and based on the pictures alone, this seem to be a "hack" I was not even considering to do 20 years ago when I started this.
Please do correct me if I am wrong and I apologize to the company making this product if my assumption is wrong, but do they also require by any chance to have a CD inserted in the CD Changer that will play all the time in order for the Bluetooth to operate?
Because if that is the case, and again just lookin at the harness pictured, seem to be that way, what they do is disconnect the audio line from the CD changer and splice in the Bluetooth.
Basically as far as the CD Changer is concerned, it is communicating with the radio and is playing a CD as requested by the radio,
As far as the radio is concerned, it communicates with the CD changer (trough the E&C data line) and the CD changer is playing a disk, but what none of the CD Changer and the Radio know is that somebody cut the audio line and injects a different signal in (the one from the Bluetooth).
I would never do this, because you basically are wearing out the CD changer, playing in the background, just to keep the radio thinking that is talking with the CD Changer.
So if this is the case, then that device is basically 1% of what I did.
My device is literally replacing the CD Changer, my device will "talk" with the radio (on the E&C data) using the same exact instructions as the OEM CD changer. This took me years and year (and many nights) of studying to decipher the communication protocol. The effort is similar with braking into 1000 different safes, that's how difficult it was, having no documentation to rely on.
I literally cloned what Delco Electronics did back in 1995-1996 (when this CD changer was being developed).
So you don't need the CD Changer connected to the Radio, my device replaces the CD changer 100%. I can also connect the CD Changer to my device (if you want to preserve it), but there is a switch that sets my device in pass trough mode, and allows the radio to communicate with the CD Changer, or can disconnect fully the CD Changer from the radio and allow my device to communicated with the radio.
And yes, my device has mp3 decoding capabilities to read and decode mp3 files from a micro SD card reader or a USB Flash Drive, and it also includes a Bluetooth receiver that can be selected as a "virtual disk".
But because my device is communicating with the radio, I can also take commands from the radio "<" or ">" to forward via Bluetooth to whatever device is connected to it to navigate trough the playlist. Meanwhile the display on the radio displays exactly what you are listening, the buttons on the radio, do exactly what you are expecting to do.
I read on a thread here that somebody found a product that can add aux input to the C5 Radio, but is not a FM Modulator because it connects directly to the radio antenna, well that IS a FM modulator then, is just a very week signal that needs to be much closer to the antenna to be picked up, which at the end is preferable because people around you cannot tune into your signal (well they still can but is weak).
*EIDT
I just saw the product description (you need to scroll down on the page), it is EXACTLY what I assumed it is:
"» Requires and retains original factory radio and 12-disc changer (changer must be fully functional)"
I will not comment on this product, but I will try to educate people to understand what they are buying. It is a very primitive hack, something that a 16 y.o. will do to the car, you are wearing out your CD Changer playing in the background for no reason. Also none of the buttons on the radio will do anything, and the display will show paying some disk/track with no relation with the sound.
This is NOT what I did, I am talking quantum science vs caveman tossing a rock.
Last edited by 1KRetrofit; Apr 7, 2025 at 01:41 PM.
I'll leave you to it... but, these cables are pretty common. I had one "back in the day," I believe it was from PAC... you could plug it into the CD changer cord where it meets in the passenger footwell (all c5's with the upgraded stereo had a connector in the passenger footwell for a CD changer, regardless of whether you had the changer). The PAC cable plugged into that cable, and if you wanted, the other end plugged into the CD changer. You could use the forward/next buttons on your head unit, or just connect using bluetooth to your phone. Worked great-- I actually used it for bluetooth to connect my phone, and also an AUX input to connect my (then state of the art) XM radio.
Others have used the DCS cable, and I'm sure at some point they'll weigh in... I've since replaced everything in my car, and sold the PAC cable... but I'm pretty sure you don't have to use the CD changer with it, wouldn't make sense. But like I said, I'll leave you to it.
Edit: My memory is correct -- they used to sell one that does not require a working cd changer-- model number bt6-c5 and bt3-c5, enabled bluetooth streaming, hands free calls, etc, but those two didn't include the SD card compatibility (the one I linked above did) -- and again, didn't require a cd changer. I don't think they're making those anymore though.
Thank you very much for the links! Very informative.
So looks like one of the options was indeed communicating with the radio on the E&C data line. I assume it has the minimum protocol implementation (just one disk layout with fix number of "tracks" and is able to react to the instructions (3 of them) to select disk and track. if anybody can point me to some video showcasing how it works it would be great, I will have a better understanding of the product capabilities than going trough that marketing material.
But I did read somewhere that a ACC wire is required, and I know exactly why. The comfort power circuit (the one powering the CD Changer, among some others) is hot all the time.
They do not know how to shut down and most importantly power on the device when the E&C data line has communication on it.
That circuit alone takes 7 transistors and some other components to make it work, What happens the radio keeps the E&C data line to positive voltage as long as there is no communication. 5 minutes after the RAP times out some radios (depending on model and year) send a "end" message to the E&C data line, some don't. Unfortunately the message is not specific enough to indicate that the CD changer is no longer needed ON, is just simply saying "stop playing" (in case it was playing). The same message is also sent when the radio is turned off (from the button), but we all know that is not actually turned off, is just shutting down the display, it is still working monitoring the OBDII data line and producing the chimes and (at least in the Cadillac) displaying the time. What I am trying to say is this message is too generic to indicate "power off", can't be used for this purpose. So the CD changer will simply shut down after a certain amount of "silence" on the E&C data line.,
24h after the RAP was timed out, the Radio is truly powered off (as in the radio power circuit is turned off). That is when the E&C data line goes to ground. For a not smart enough circuit, that could count as "activity on the data line" and will power on the CD Changer.
Anyways, very complex issue, the solution to it, at least my solution, was to create a power management circuit that is sensitive at the transition from low to high, that is the only transition that really means "wake up, there is activity on the data line". This allows me to deep sleep my device while is not needed, and the circuit managing this uses ~13 nA for that, while the original CD changer is using ~230 nA and the overall drain on battery with all circuits off (let's say 15 min after the car was locked) is ~28 mA.
As I mentioned, my goal is absolutely total plug and play solution, no comprise, no professional installer needed.
I really appreciate if anybody can volunteer 10-20 min of their time and vehicle to test my device in the C5.
Must be in Toronto Ontario area.
Thank you very much for the links! Very informative.
not sure what the difference is in your product, but doesn't matter, the ones that linked to that don't require the cd changer do not seem to be on sale anymore -- so, good luck !!
Thank you for the reply,
I tried to send you a PM, but I get an error indicating that you have not activated the option to receive PMs.
Is either that, or is some generic error and actually I am a not allowed to send PMs being a new member.
Anyways I was trying to explain in the message that I do not have any plans (better said time) to get into your area anytime in the foreseeable future (last I was in Ottawa was 2 years ago).
I would definitely not ask you to travel this far just for me, but if you happen to have a reason (other than me) and have time, I will be very thankful.
Another option, probably more realistic, is if you happen to have a contact in my area for somebody with a C5 that is willing to assist me.
I need to be by the car and have my computer connected to the device to monitor live the logs.
@1KRetrofit
Another Q, do you know the name of the black connector you listed?
Or the receiving "female" for it?
I want to try some experiments myself.
Regarding the connector, I already replied to the PM but perhaps it is useful information for somebody else.
The male connector (the one on the CD changer side) is manufactured by Aptiv.
The P# is: 12065647
It was discontinued, but can be put back in production, minimum order QTY is ~700 pc and lead time is 24 month.
Last time I checked they had 4 left in stock.
If you need more than 4, it will take 2 years and many thousands dollars to get the 5-th one.
However I did received from Aptiv the technical drawings (there is a process you can submit a request for the drawings).
I was able to re-created it in CAD so I can 3D print it myself, when I need, as many as I need.
The Female connector (the harness side), is the same manufacturer. I was unable yet to identify the single piece (10 pins) P#, but I was able to identify the 6 and 4 pins version which can be used instead.
The main body P#:
6 Pin: 12064993
4 Pin: 12066189
The wire lock (aka "the comb") PN#:
6 Pin: 12066170
4 Pin: 12059160
The lock can be used for other pin configurations (like 12 pin 6x2, or 8 pins 4x2). Only the connector body P# will be different.
This is a picture of the previous version of the "naked" PCB for the 1K Changer, see the mouse as a size compare and also you can see the 3D printed connector (exact clone of original Aptiv P#12065647).
The latest version of the PCB is smaller, and is using a different chip, also the layout is significantly different.
Still looking for somebody within Toronto/GTA Ontario with a C5 willing to volunteer his/her time and vehicle for 10-20 minutes test (driving not required, but I need to be able to put the car in ACC so the radio is ON).
I mentioned before, the firmware is complete, I am not expecting to make more (significant) changes, of course is possible to still find a bug that I need to address, but that's just "polishing". I already completed the long term test for the 21 days sleep mode (yeah, I had to have it in the car for that long until the car goes to deep sleep/storage mode, where it kills even the RFA).
The last "major" update was the logic to build the indexing of the SD Card or the USB Thumb Drive content, whichever is inserted last.
Small background, when the magazine is inserted, the OEM CD Changer goes trough the ~90 seconds sequence of loading one by one the trays to "see' which tray has a disk, and if it does, reads the tracks (number/duration). Basically it builds in its memory the disks layout. Once this is done, it will communicate the layout to the Radio. While the CD Changer does its loading thing, the radio will show the CD changer symbol flashing, or displays "initiating', depending on the radio model.
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Well this video shows my version of the same process, I will come bluntly:1 second (see how long the CD Changer icon is flashing). Is not because I have some supernatural programming powers or something, is simply the difference between a mechanical thing that has to move trays, spin disks turn on a laser diode and focus it then "glide" it across the disk and, a solid state memory that is, as far as I am concerned, nearly instant.
The reality is a bit different, it does takes about 8 seconds to read a brand new SD Card or USB Stick (by "new" I mean unknown to the unit), worst case scenario, 1188 files or around 4.75GB of data. There is nothing that can be improved there. My solution was the ability to "recognize" when is the same exact memory content that I already know, so I don't have to read it again. I like to say that the fastest code possible is the one you don't have to execute.
As shown in the video, it takes ~9 seconds from the moment I power up until I am able to play the first file, that including me pressing buttons to select the proper audio source.
Normally the 1k Changer is waked up when the car is unlocked, or a trunk or a door is opened, is pretty much impossible to turn on the radio that fast. Or if you are changing the SD Card or USB Stick (which in most vehicles is done in the trunk), by the time you are in the car is already available. And if anyone is able to get to the radio that fast, then is a matter of watching that icon blinking until it goes solid, just like is done with the OEM CD changer.
Interesting detail, count how many views the vides above has, you are that number + 3 person to hear an MP3 playing from this '98-'02 Cadillac Radio. We did had mp3s at the time but they came with a large desktop and an even bigger(heavier) CRT.
The hardware shown in the video is emulating enough of a "car" (Cadillac STS) to keep the Theftlock happy, or the radio will not run. That is the "lab" test environment, I don't need to bring the whole car inside.
At some point I will make a "how to" video, but I need to make a proper case first (currently while in the car is in a cardboard box). Until then, here is something that not many people have ever seen, outside perhaps the engineers from Delco Electronics. I call this "I have 99 problems but the memory size is not one". The times we are living, we can store more data that it was conceivable in the late 80's, when the E&C protocol was defined. They only allow 2 digits for the counter, and they wasted 1 full byte for that! Is because is in BCD, if they just specified this as binary it would have allowed 256. And this is why we cannot have more than 99 tracks per disk.
I am still looking for a C5 Corvette owner in the Toronto/GTA area willing to volunteer few minutes of his/her time and car, so I can test the 1k Changer in these vehicles.
Last edited by 1KRetrofit; Apr 15, 2025 at 01:02 AM.
why don't you just buy a headunit? they go for less than $100 on ebay, I see several on for around $70. They come up ALL the time in the parts forum on this site for between $50-$100... ****, if I could find mine I'd send it to you for shipping. Seems a LOT easier than trying to coordinate meeting with someone, and spending time taking their car apart. No offense, but I'd never let someone else pull my car apart to test out an experimental interface. Sound like you have a lot of work left, getting a head unit and setting it up on your bench seems like your best option.
@JMG2 I think you may be missing 1Ks goal
Obviously if pure functionality is what you are after, the $100 Chinese radio with bluetooth, Apple CarPlay and Android auto would be better.
Many people, myself included, want to keep the look of the factory radio but have the ability to stream our music.
Looks to me like this is a passion project for 1K and he's just asking for some help
Brother, I'm going to tell you.... I ran a dongle to the CD-changer port on the oem head unit in my last car.
The dongle adapted out to a USB and was pretty cheap.
From there I just used a $20 BT adapter in my arm rest and plugged to the power adapter and ran all that complicated SD / feed / selection / calls / yadda yadda off my phone.
I think total expense was about $100 for hands-free, wifi, sd, music, movies, calls, navigation, you name it.
Brother, I'm going to tell you.... I ran a dongle to the CD-changer port on the oem head unit in my last car.
The dongle adapted out to a USB and was pretty cheap.
From there I just used a $20 BT adapter in my arm rest and plugged to the power adapter and ran all that complicated SD / feed / selection / calls / yadda yadda off my phone.
I think total expense was about $100 for hands-free, wifi, sd, music, movies, calls, navigation, you name it.
Hey!
Link to the dongle you speak of? I'd be interested in that!!
Oh my God, I realize that I didn't made my self understood, let me clarify:
1. The 1K CD Changer Replacement is fully functional and fully tested in Cadillacs (various '97-'02 models).
2. Prior to plugging it in the C5, I will demonstrate its functionality in a Cadillac, the owner of the Corvette is allowed to do any test it wants while in the Cadillac.
3. The most important, nothing will be pulled apart, the CD change is located in the trunk, here is the location in the trunk:
No screw or panel needs to be removed/popped. the only thing I need to do is reach behind to disconnect the the harness from the back of the CD Changer and plug the 1K Changer in.
If you are comfortable to plug a phone charger into the cigarette lighter, this is a similar process. The test is done with the car stationary, and either I can instruct the owner what buttons to press on the radio for testing, or if the owner is ok, I will be doing the buttons pressing.
The video I posted was to show that it works with the OEM Radio (and is incredibly fast), it is an early prototype I am still using for bench testing, please understand that is NOT what will be plugged to the car, it will be a module of the approximate size of a smaller cell phone (think chubby/stubby iPhone) with a proper case.
Regarding why I need a car instead of buying a Radio from eBay or whenever. The issue is the antitheft, all GM Radios '97 and newer have the so called "Theftlock". The way it works is every time the radio is started posts a message on the car data bus "what is the VIN?" and one of the modules will reply. The radio stores in its EEPROM the first VIN it ever read (i.e. when installed first time in the car at the factory). If the VIN it received from the data bus is the same, it means is in the same car, so will proceed starting, if is not matching (or not received at all) will not start, post a OBDII IPC Code and display "Theft lock enabled".
Which module will respond with the VIN depends on the year and model. For example in the '96-'97 Cadillac Seville, '96-'99 Deville and '96-'02 Eldorado that module is the IPC, on the '98-'03(4) Seville, '00-'04 Deville is the DIM. If you watch the video I posted, you see above the Radio I have a '97 IPC, that is what replies to the Radio the VIN so the radio turns on instead of displaying "Theft Lock".
The problem is, I am not familiar with the C5 Corvette, thus I don't know which module replies with the VIN, I will need to get that module as well, along with the radio. This module must be either from the same car (so is a matching VIN), or if not will be more complicated.
If you need to install a used radio in a car, you need to do a so called "VIN re-learn procedure". That essentially erases the currently stored VIN from the replacement radio's EEPROM, so when it turns on (in the car that was just installed), will store the new VIN and basically lock on it. For this you need either a TechII ($$$) or some aftermarket OBDII scanner like some of the Autel scanners ($$). Even though I do have access to an Autel scanner, I still don't know what other module I need from the Corvette (plus the wiring diagram). So yes, if is a matter of due or die, at great inconvenience, I can set up a C5 bench test. But at the end of the day, as I learned with the Cadillacs, you still need to have it tested in an actual vehicle, because of various factors you will not see in the test environment (for example when you crank the engine and you have a brownout to the module, RAP timings...).
TBH, I was just trying to look it up to offer here but it was clearly not an Amazon purchase.
I remember it being a dark green and black box. To switch to it I had to hit the CD/Aux button on the head unit under the Eject button. It plugged in directly to the head unit.
I tried running a few searches on the forum here real quick and can't find the direct product which was definitely linked here somewhere.
There are pxdp / pxhgm4 combos coming up. Add ISBT23 for bt use.
IL-C5FM coming up and no longer available.
DCS-GM2 which adds an Aux adapter to CD changer harness.
BTH-C5 for cars with the changer. Corvette Central sells a box for $143
One BLU-C5 adapter is on Ebay currently. BTA-C5 adapter.
Caddy GM-10 option.
>>> Ok, in searching I believe I had used the iSimple box (which is the PXDX combo listed above) as I found a picture of it as dark green box at the link. <<<
But it does appear many options are fading away and no longer being produced since Covid.
In which case.... adding your own Aux port is pretty easy, just time consuming. Or adding an aftermarket head unit adds all the functions you want and then some.
CD Changer development
