2006 Citroen C5 audio system

[GiveMeABreak]

The Head unit is held in place by 2 x Torx 10 screws. A word of advice - before undertaking any work on the head unit and before disconnecting anything, open the bonnet, and follow the battery disconnection procedure first. Allow all the ECUs to sleep before disconnecting the battery negative. Then always disconnect the large Quad lock connector FIRST, before any of the other inputs. and attach it back LAST on reconnection.

[Takshaka]

Are you referring to a battery disconnection procedure specific to this car or do you just mean remove Negative then Positive? How do I know when the ECUs are asleep? Thanks

[GiveMeABreak]

Modern cars especially PSA vehicles have complex electronic data networks that connect all the various electronic control units (ECUs). The main computer controls these units by sending digital data signals through the different networks. They can can stay on for a while after the vehicle is switched off and locked. Normally, they shut themselves off after a certain amount of time. If you disconnect the battery before they have gone to sleep, the ECUs may not shut down properly, leaving them in a state of limbo when the power is returned unexpectedly. Therefore we should always allow the ECUs to be properly shut down and powered up correctly to Void potential issues.

Ths is the procedure before disconnecting the battery and then for reconnecting it:

BSI Rest / Battery Disconnect / Reconnect Procedure