BMW CCC repair : the correct diagnosis

Your CCC unit appears to be malfunctioning and you’re thinking of having it repaired or even replaced ? Before you proceed, we recommend to verify your CCC diagnosis to make sure it’s really a CCC failure. With the right guiding, it can be a quick and painless process. And it can avoid unnecessary costs. Here’s how to correctly diagnose a CCC failure.

First, read through our compiled list of symptoms that are normally caused by a faulty CCC head unit:

• CCC iDrive reset: the CCC head unit reboots continuously, as a result your screen cycles between the BMW logo and a black screen
• The CCC iDrive does not boot completely thus, when started, it remains blocked on the BMW logo.
• The iDrive is fully functional on particular days only, most likely when the weather is colder.
• The CCC head unit might work when the car is cold, but fails to work when the car is warm
• The CCC iDrive is completely non functional, as a result your screen remains blank.
• The cooling fan of the CCC iDrive remains on, consequently draining the car battery
• The CCC console buttons lights remain always on

We also have a list of symptoms that may have other causes:

• Slow navigation menu: the CCC iDrive is slow (has a lag) in executing user commands
• Intermittent sound
• The CCC headunit randomly freezes and the iDrive controller / the joystick spins freely
• The CCC iDrive resets a few times, but then starts and works properly

For the symptoms above, your CCC diagnosis may be wrong. Here are the possible other causes:

• The CCC has trouble reading the CD / DVD. Remove all disks and test again. If a disk does not come out by itself, please do not force it out (as this may cause mechanical damage).
• Another module connected to the fiber optics ring if faulty and prevents the proper functioning of the CCC iDrive. The most common other causes: the bluetooth module (MULF or MULF 2) and the sound amplifier (TOP-HIFI, also known as Logic 7).

Troubleshooting other possibles causes:

• First, check whether your car comes with the bluetooth and / or sound amplifier modules that are known to be prone to failure. Enter the last 7 characters of your VIN number here or here and see if the generated list includes:
  • 644 Preparation f mobile phone w Bluetooth – this is the MULF or MULF 2
  • 677 HIFI System Professional – the TOP HIFI (also known as Logic 7) sound amplifier
• Next, remove the module identified on the previous step in one of the following two ways:
  • replace the above with a known to be functional module (from a friend, a local service etcetera)
  • remove the suspect unit and use a MOST bypass loop connector to close back the optical fiber loop. This is mandatory. If you simply unplug a module and do not close the optical fiber ring, all modules that work on the fiber optics will stop functioning and your test will not be relevant.

Why it’s important to close the fiber optics ring when troubleshooting:
For example, let’s say you have a sound problem on your car: the sound gets interrupted from time to time. Let’s assume your car has a CCC iDrive navigation, no external sound amplifier, a MULF bluetooth and some other modules attached to the fiber optics. In this case, if you don’t have a separate sound amplifier, the sound is produced by the CCC iDrive. This part of the CCC fails rarely (but we’ve seen it happen, so it’s not out of the questions). However, if another module that is attached on the fiber optics is malfunctioning, it can also interrupt the sound from the CCC iDrive.
Let’s assume you suspect the MULF to be the faulty module. You disconnect the MULF and then you test the sound and see the sound is working perfectly. You then draw the hasty conclusion that the MULF is faulty.
The error in this case: when you disconnected the MULF, all other modules from the fiber optics are disconnected except for the CCC iDrive. It’s as if you disconnected all other modules, so it’s impossible to tell if the MULF or the others are faulty. The only conclusion you can draw in this case is that the CCC iDrive sound processing is working fine.
The correct approach: you disconnect the MULF and you fit a loop MOST connector instead. Now all other modules attached to the fiber optics are still connected. Only in this case, if the sound proves to be working after the MULF removal, you can draw the correct conlusion that the MULF must be faulty.
Take home message: always fit a MOST bypass loop connector to close back the optical fiber loop when disconnecting one module for testing purposes.

Next step: Once you have identified the faulty module, whether you confirmed or not your initial CCC diagnosis, we can help with the necessary repair. Please see:

• our CCC repair page
• our MULF / MULF 2 bluetooth repair page
• our Logic 7 amplifier repairpage

Thanks for reading through. Did you find our short guide helpful ? If there’s anything we missed or if you have a question, please feel free to leave a message and we will get back to you in a jiffy.