This is a shorter version of the TSB given to me regarding battery dis-connects on Peugeot Citroen BSi units:PROCEDURE FOR BATTERY DIS-CONNECTION (The 3 Minute Rule)
Whenever a vehicle battery has to be dis-connected, switch off all equipment, interior lights etc, close the doors leaving the drivers window open.
Switch off the ignition and remove the key and any DIAG equipment.
Wait a full 3 minutes before disconnecting the battery.
The BSi must be allowed to go to SLEEP ie into "power save mode". Do not operate any equipment on the vehicle during this time. Remember, even opening the bonnet will wake the BSi on a vehicle fitted with alarm.
If the battery is under the bonnet, open the bonnet first and leave it up. 807 batteries can be dis-connected through the drivers window, remove floor cover first.
ALWAYS disconnect any DIAG equipment and do not operate any plips from other vehicles during the 3 minute waiting period.
PROCEDURE FOR BATTERY RECONNECTION
Unless otherwise instructed by Peugeot or Product Service, you must always carry out the following procedure, often referred to as a "soft re-boot", to minimise the possibility of the BSi corrupting its own software when reconnecting the vehicles battery supply.
Ensure the procedure for battery disconnection has been adhered to and importantly all BSi functions were switched off with the drivers window left down.
1 Close all doors
2 Remove ignition key if left in ignition
3 Reconnect battery. DO NOT open any doors
4 Wait 10 seconds
5 Switch on healights through the drivers window (you will hear a "bong")
6 Switch on ignition then start the vehicle and check system functions
NOTE: Upon reconnection, if any vehicle function controlled by the BSi i.e . interior light is switched on,the internal operation of the BSi has the potential to spike or corrupt its configuration and software program......
(this was on paper, my fingers now hurt!!!)