PASSENGER COMPARTMENT CONNECTION UNIT
Fault finding - System operation
87B
87B-36
PASSENGER COMPARTMENT CONNECTION UNIT
Fault finding - System operation
87B
87B-36V9 MR-372-J84-87B000$086.mif
UCH
Vdiag No.: 44, 48,
4C, 4D, 4F, 50
1.4.3.7 Automatic gearbox computer (if fitted):
The computer informs the UCH of the selector position (park, neutral, etc.) via the multiplex network.
2 AIR CONDITIONING FUNCTION
The type of air conditioning control can be displayed by configuration reading LC013 Air conditioning type and
configured using command CF019 Air conditioning type (can be configured during configuration of the UCH
by the SC008 UCH type command).
2.1 Sub-function: USER SELECTION (Non-regulated air conditioning only)
The UCH receives the signal from the air conditioning panel via cable connection for the air conditioning request, for
electric heated rear screen and the signal for passenger compartment blower operation.
The UCH sends the request to the Protection and Switching Unit to start electric heated rear screen de-icing.
The UCH sends the request to the injection system to activate the air conditioning compressor.
The following statuses can be displayed:
–ET029 Air conditioning button.
–ET028 Heated rear screen button.
–ET015 Passenger compartment fan.
Operation of the indicator lights on the air conditioning and electric heated rear screen request buttons can be
checked using the following actuator commands:
AC015 Air conditioning button indicator and AC019 Heated rear screen indicator.
2.2 Sub-function: HEATING
The UCH manages the passenger compartment heating resistors (RCHs) by controlling power relays according to
the request for ventilation in the passenger compartment, the engine coolant temperature, the external temperature,
the electrical power balance, engine loading and, for the cabriolet version, if the roof is open.
The following statuses and parameters produced by the UCH can be displayed:
–PR001 Battery voltage.
–PR002 External temperature.
–ET015 Passenger compartment blower only with non-regulated air conditioning.
–ET017 Number of RCH*s required.
–ET018 Number of RCH*s authorised by alternator alternator charge rate.
–ET019 Number of RCH*s authorised by injection system.
–ET020 Number of RCH*s activated.
–ET021 RCH* 1 control.
–ET022 RCH* 2 control.
–ET031 Fast idle request for RCH.
–ET169 Engine.
–ET025 Retractable roof for cabriolet version only.
–ET026 Heated rear screen switch.
*RCH = Passenger Compartment Heating Resistors
PASSENGER COMPARTMENT CONNECTION UNIT
Fault finding - Interpretation of statuses
87B
87B -147
PASSENGER COMPARTMENT CONNECTION UNIT
Fault finding - Interpretation of statuses
87B
87B -147V9 MR-372-J84-87B000$473.mif
UCH
Vdiag No.: 44, 48,
4C, 4D, 4F, 50
*RCH = Passenger Compartment Heating ResistorET017
NUMBER OF RCH* REQUIRED
NOTESThere must be no present or stored faults.
The status, depending on the conditions, will be 0, 1, 2, 3, 4 or 5.
Special note:
Manual air conditioning (not automatic)
Defined by the UCH according to the engine coolant temperature, the external
temperature and electrical availability.
Climate control
Defined by the UCH according to the engine coolant temperature, the external
temperature, electrical availability, the internal temperature and the user's request.
The passenger compartment heating resistor control conditions are:
Manual air conditioning (not automatic):
ET169 Engine is Running,
ET015 Passenger compartment fan Active,
PR002 Exterior temperature < 5˚C
Engine coolant temperature < 50˚C (refer to injection computer),
Electrical availability - 60%, alternator load < 70% (refer to the Power and Switching Unit).
Climate control:
ET169 Engine is Running,
PR002 Exterior temperature < 5˚C
Engine coolant temperature < 50˚C (refer to injection computer).
Electrical availability - 60%, alternator charge < 70% (refer to the Power and Switching Unit).
Heat demand by the user (refer to the climate control computer).
Check the consistency of these statuses and parameters.
In the event of a fault, consult the interpretation of these statuses and parameters.
AFTER REPAIRCarry out another fault finding check on the system.
Clear the stored faults.
Deal with any other faults.
UCH_V44_ET017/UCH_V48_ET017/ UCH_V4C_ET017/
UCH_V4D_ET017 /UCH_V4F_ET017/UCH_V50_ET017
