Recommended Posts

I recently lost some radio/cd/nav/hard drive unit functionality (no output to nav touchscreen, unable to access music on hard drive, CD player not working) in my 2009 CTS.  I replaced the entire unit (GM part # 25979736 with an identical unit from another 2009 CTS, and it displays the expected "locked" message on my touchscreen.  I took it to my local dealer to have it unlocked but they were not successful.  The report from the service technician stated that he:  (1) verified communication with the radio through the diagnostic port, (2) programmed the radio with the latest calibrations (radio did not unlock),  and (3) attempted to reset the radio manually (radio did not unlock).  The report then stated I would need a new unit, and that the VIN burn for this radio is "one-time only".

Has anyone ever heard of this or experienced a similar problem?  Or should I assume the service technician didn't know the proper procedure to unlock the radio?  My understanding is that I should be able to unlock it myself if I have access to a GM Tech2 scan tool.  Has anyone ever unlocked this particular radio from the 2009 CTS or had one unlocked by the dealer?  It doesn't sound plausible to me that GM would make a part that can't be reprogrammed or relearn the VIN for another vehicle.

Share this post


Link to post
Share on other sites

Most GM systems for almost 20 years are on a network. 

It's true that most of the modules on the network use the VIN # to verify the component to the vehicle. 

The VIN can only be programmed into the module the first time / one time. 

If the VIN is a mismatch....not working and a network mismatch code. 

You may be able to take the radio to a Delco Radio / Speedometer repair facility to have the VIN erased out of the unit. Pretty sure a Tech 2 won't do it (just like a Tech 2 cannot change the vehicle mileage).

 

Sometimes we try different clusters and such.....if they work.....we call it 'plug-n-play' and will report that here. ( Example: DTS cluster in base Deville.)

Share this post


Link to post
Share on other sites

Thx for your response Logan, appreciate you taking the time to share your knowledge with me.  It's perplexing to me that the technicians at a GM/Cadillac dealer wouldn't know if an OEM module could be unlocked or not with their own diagnostic and programming tools.  They spent a few hours trying to unlock my module, so it seems they believed it was possible.  I've asked around from a few other automotive techs, and they all seem to believe the unlock should be simple, and have never heard of "one-time only VIN programming".  Also, I have found instructions on the web for performing a VIN relearn / unlock sequence on GM navigation radios using the Tech 2:

http://www.obd2tuning.com/news/gm-tech-2-scanner-vetronix-tech-2-scan-unlock-gm-radio-manual-a-1124.html

As an alternate solution, I've also seen a number of videos & posts where the eeprom containing the VIN is removed (or unpowered) as a solution, however I have as yet been unable to locate an eeprom on the circuit boards from the old module I took out.  I am starting to wonder whether the issue is related to my module being a full system (am/fm/xm radio, video disc player, navigation, mp3, and hard drive) complete with system software licensed to GM by Microsoft.  Perhaps this system is engineered differently than the standard radio + disc player configurations, and requires a different unlock sequence, but then again I would expect the GM technicians to know that!

 

Share this post


Link to post
Share on other sites

GM has a service bulletin.

"GM Technical service bulletin TSB Class 2 trouble code B1000, B1001, B1271, B1780

Class 2 Serial Data Communication allows control modules (i.e. the Powertrain Control Module (PCM), the Body Control Module (BCM), the Dash Integration Module (DIM), the Instrument Panel Cluster (IPC), the radio, the Heating, Ventilation and Air Conditioning (HVAC) Controller, and the Sensing and Diagnostic Module (SDM) to exchange information. This information may be operational information or identification information. Among the identification information exchanged and compared within these modules is the Vehicle Identification Number (VIN). Typically the one module, the master module, broadcasts the VIN and all the other modules compare the VIN stored within itself. When the broadcast VIN does not match the VIN stored within the SDM, the following actions occur:

• DTC B1001 Option Configuration Error is set and deployment of the airbags is inhibited.

• DTC B1271 or a DTC B1780 Theft Locked.

The VIN information is also used by the radio. When the VIN does not match the VIN stored within the radio, DTC B1271 or DTC B1780 is set and the radio is inoperative.

Additionally, the master module will compare the SDM's part number (last four digits) to determine if the correct SDM is installed in the vehicle. If the SDM is the wrong part, a B1001 will also set.

This situation may occur when a vehicle is being repaired. When a PCM or a body control type module is replaced, the VIN information must be programmed into the replaced (new) control module. A module which has had VIN information entered into it (for example, one taken from another vehicle) cannot be reprogrammed. VIN information can only be entered into new modules. The ignition must be ON in order to program the control module. Since the VIN information is broadcast when the ignition goes to ON from any other ignition switch position, DTCs may be set in the SDM and/or the radio. Therefore, always follow the specified control module replacement procedures."

 

 

It's a bit of a crap shoot......the 2010 CTS lock code procedure may be different than a 2009 CTS. The Tech 2 menu can be different between years. Can you trick a 2011 Silverado radio to work in a 2012 Yukon?  Endless possibilities. Sometimes it works.

I would expect the top end navigation radio to be kind of hard to get unlocked. If it was easy...everyone would be doing it. Surely it can be done....just not by using a GM dealer or Tech 2 in this case. But I'm sure they were willing to give it a try for a couple hours of labor. 

BMW (Mini Cooper) is the same way. Some stuff requires a laptop and new coding to get it to work. Some stuff is plug n play. 

Kind of a related example. There is a cottage industry out there resetting air bag modules. After a deployment the module becomes locked....the GM service manual has you replace the module.  A Tech 2 will not clear the lock. Companies have sprung up going in and clearing the EEPROM. 

Share this post


Link to post
Share on other sites

Thx again for posting the info from the service bulletin.  Looks like my dealer's technicians learned about this for the first time trying to reprogram the salvage module I installed.

Just to finish up this thread, the last thing I tried was complete disassembly of the module (which has about 5 different circuit boards layered in the chassis) to see if I could locate a board with an eeprom containing the VIN.  I was unable to locate an eeprom on any of the boards, but decided the VIN was probably stored on one of the 2 boards with CAN bus interfaces on them (audio board and main board).  I tried swapping out each of these boards for boards from the module with the non-matching VIN.  When the audio board was swapped out, the module remained locked, but when the main board was swapped out with my original board, the system unlocked.  Unfortunately, the main board with my correct VIN was probably also the board that was not functioning correctly in my original system, since I am now back to the original functionality (only some aspects of the system work).

Bottom line seems to be that the simplest solution may be to just buy a new, unprogrammed module.

 

Share this post


Link to post
Share on other sites
15 hours ago, BoydRB said:

Thx again for posting the info from the service bulletin.  Looks like my dealer's technicians learned about this for the first time trying to reprogram the salvage module I installed.

Just to finish up this thread, the last thing I tried was complete disassembly of the module (which has about 5 different circuit boards layered in the chassis) to see if I could locate a board with an eeprom containing the VIN.  I was unable to locate an eeprom on any of the boards, but decided the VIN was probably stored on one of the 2 boards with CAN bus interfaces on them (audio board and main board).  I tried swapping out each of these boards for boards from the module with the non-matching VIN.  When the audio board was swapped out, the module remained locked, but when the main board was swapped out with my original board, the system unlocked.  Unfortunately, the main board with my correct VIN was probably also the board that was not functioning correctly in my original system, since I am now back to the original functionality (only some aspects of the system work).

Bottom line seems to be that the simplest solution may be to just buy a new, unprogrammed module.

 

Keep us up to date with your progress on this, thank you @BoydRB


Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


  • Recently Browsing   0 members

    No registered users viewing this page.