87B-9
MR-413-X44-87B000$192.mif
V5
87B
PASSENGER COMPARTMENT CONNECTION UNIT
Fault finding - Role of components
GENERAL OPERATION
The UCH is involved in the following five functions (shared between several computers):
–Access-security function
This function is divided into three sub-functions: Access, Protection and Starting (see 82D, Access - Safety).
–Air heating and manual air conditioning function
This function is divided into four sub-functions, which are: User selection, Heating, Cold loop and Passenger
compartment ventilation (see 61A, Heating and see 62C, Manual air conditioning).
In this function, the UCH manages the heated rear screen operation indicator lights, heating controls and air
conditioning activation requests, by sending requests to the engine management computer:
–In the case of a vehicle fitted with manual air conditioning, by pressing on the air conditioning button.
–In the case of a vehicle fitted with climate control, by request from the user or the climate control computer in
automatic mode.
–Wiping function
This function is divided into two sub-functions, which are: Wiper control and Wiper power (see 85A,
Wiping-washing).
–Lighting Function
This function is divided into two sub-functions, which are: Lighting control and Lighting power (see 80D, Lighting).
–Energy management function
Note: There is no UPC on this vehicle; this function is managed by the UCH.
The system is composed of the UCH which stores the programming for electrical energy management, the starter,
the battery, and the alternator controlled via a BSS connection.
The role of this system is:
●to ensure electrical energy is supplied to the vehicle whilst respecting the dynamic performance
constraints of the engine and transmission assembly,
●to control alternator loading* and load shedding** during engine management authorisation or variation of
the electrical load,
●to ensure the quality of the on board network voltage in terms of the voltage level and variation,
●to optimise the battery charge by applying a voltage to its terminals correlating to its initial charge status
(in sleep mode) and to its internal temperature,
●to inform the engine management about the mechanical power taken from the accessories pulley, the
alternator charge rate and the rotor excitation current value,
●to run fault finding on the charging circuit: “Battery” warning light display.
*loading: This operation consists of transferring control of the vehicle's electrical consumption from the battery
to the alternator.
**load shedding: This operation consists of involving the battery in the vehicle's general electric power balance.
MR-413-X44-87B000$192.mif
UCH
Vdiag No.: 44
