Attention! Before any work on the electrical system, read the precautions described in paragraph «Safety first!» at the beginning of this manual and chapter 5A.
The electrical system has a supply voltage of 12 V, the negative terminals are connected to «weight». All lights and all electrical accessories are powered by a lead-acid battery that is recharged by a generator.
Since model year 2001, many body electrical systems are controlled by separate electronic control units (BEU). and they, in turn, are controlled by the main BEU. known as the BSI block (for an explanation of the abbreviation, see paragraph 22). The various electronic control units and the BSI unit communicate with each other via a multiplex network. The multiplex network is a two-wire system that links the BSI unit to the electronic control units of various vehicle systems. Peugeot/Citroen uses CAN networks to communicate (data exchange via Controller Area Network protocol) and VAN (data exchange via Vehicle Area Network protocol). This means that the BSI and all electronic control units that control the comfort, safety, security and entertainment systems of the vehicle communicate via these two networks.
The electronic control unit connected to the multiplex network, along with the data required for the operation of a particular system, receives a number of data supplied by other ECUs connected to the network. Because the electronic control units share the information supplied over the network, several units can control the operation of the same system. In addition, one BEU can control several systems offline. The BSI unit is a device that manages the exchange of information, and is also responsible for managing certain vehicle systems. The BSI unit has a built-in self-diagnosis function that allows you to trace any malfunction in any of the control units of the multiplex network. To do this, use diagnostic equipment that is connected to the vehicle's diagnostic connector. If any problem occurs on a networked system, contact your Peugeot/Citroen dealer or someone with the appropriate equipment for diagnosis.
This chapter covers repair and maintenance procedures for various non-engine electrical components. Information about the battery, alternator and starter can be found in chapter 5A.
It should be noted that before working on any element of the electrical system, you must first turn off the ignition and all electrical consumers. In addition, when instructed, disconnect the ground wire from the battery (refer to paragraph «Disconnecting the battery»).