87B-3
MR-413-X44-87B000$048.mif
V5
UCH
Vdiag No.: 44PASSENGER COMPARTMENT CONNECTION UNIT
Fault finding - Introduction87B
Faults
Faults are declared as either present or stored (depending on whether they appeared in a certain context and have
disappeared since, or whether they remain present but have not been diagnosed within the current context).
The present or stored status of faults should be taken into consideration when the diagnostic tool is used following
the + after ignition supply being switched on (without operating the system components).
For a present fault, apply the procedure described in the Interpretation of faults section.
For a stored fault, note the faults displayed and apply the instructions in the Notes section.
If the fault is confirmed when the instructions in the Notes section are applied, the fault is present. Deal with the fault
If the fault is not confirmed, check:
–the electrical lines which correspond to the fault,
–the connectors for these lines (for oxidation, bent pins, etc.),
–the resistance of the component detected as faulty,
–the condition of the wires (melted or split insulation, wear).
Conformity check
The aim of the conformity check is to check data that does not produce a fault on the diagnostic tool because the
data is inconsistent. Therefore, this stage is used to:
–carry out fault finding on faults that do not have a fault display, and which may correspond to a customer
complaint.
–check that the system is operating correctly and that there is no risk of a fault recurring after repairs.
This section gives the fault finding procedures for statuses and parameters and the conditions for checking them.
If a status is not behaving normally or a parameter is outside the permitted tolerance values, consult the
corresponding fault finding page.
Customer complaints - Fault finding chart
If the test with the diagnostic tool is OK but the customer complaint is still present, the fault should be dealt with by
Customer complaints.
A summary of the overall procedure to follow is provided on the following page in the
form of a flow chart.
87B-7
MR-413-X44-87B000$096.mif
V5
87B
ENGINE HARNESS
FRONT ENGINE WIRING & ADDITIONAL HEADLIGHTS
DOOR WIRING
CEILING WIRING
PASSENGER COMPARTMENT WIRING
REAR BUMPER WIRING
TAILGATE WIRING
1UCH
2Passenger Compartment Relay/Fuse Box
3Electric power-assisted steering.
4Transponder ring.
5Air conditioning panel.
6One touch window/anti-pinch module.
7Exterior temperature sensor.
8Rain/light sensor & interior temperature sensor.
9Anti-pinch/sunroof.
2ABS computer.
2Injection computer.
3Preheating unit.
4Sequential gearbox computer.
5Engine fuse and relay box.
6Alternator.
7
2
61
2
3
5
4
8
5
7
43
1
6
9
PASSENGER COMPARTMENT CONNECTION UNIT
Fault finding
- List and location of components
MR-413-X44-87B000$096.mif
UCH
Vdiag No.: 44
87B-8
MR-413-X44-87B000$144.mif
V5
87B
PASSENGER COMPARTMENT CONNECTION UNIT
Fault finding - Operating diagram
1UCH.
2Air conditioning.
3Interior lighting.
4Exterior lighting, signals.
5One touch windows and electric sunroof.
6Alarm.
7Radiofrequency key.
8Starter.
9Opening elements.
10 Front/rear wipers, washers.
11 Alternator.
12 BSS* connection
*BSS: (see Role of components, Role of connection BSS).
1
8
3
2
11
10
9
7
6
5
4
12
MR-413-X44-87B000$144.mif
UCH
Vdiag No.: 44
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
87B-10
MR-413-X44-87B000$192.mif
V5
UCH
Vdiag No.: 44PASSENGER COMPARTMENT CONNECTION UNIT
Fault finding - Role of components87B
–Energy management function
Role of BSS connection:
This bidirectional connection located between the UCH and the alternator circulates the following signals:
–Signals sent by the alternator: rotor current value, alternator charge value and electrical, thermal and
mechanical fault statuses.
–Signals sent by the UCH to the alternator: voltage setpoint, rail setpoint and rail inhibition.
Role of the DF terminal:
The signal circulating in the DF terminal is the alternator charge signal (displayed using PR073 "Alternator
charge signal") which is used to adapt the alternator supply to the demands of the electrical consumers
(such as the passenger compartment heating resistors, heated rear screen, etc.).
Depending on the battery charge status, the operating phase and the battery temperature, the UCH determines what
the voltage across the battery terminals should be.
When the battery charge drops, and PR076 Battery voltage after rest decreases, the UCH can temporarily
increase PR075 Alternator setpoint voltage by 1 V for a period of 15 minutes after switching on + after ignition
feed.
Before and during starting, PR075 Alternator setpoint voltage is fixed at 10.7 V.
A maximum of 30 seconds after the engine has started, the UCH sets PR075 Alternator setpoint voltage to the
optimum value calculated.
The injection computer can also control the alternator regulation voltage. The injection computer sends the
maximum authorised power delivered by the engine, to the UCH via the multiplex network. If this power supplied by
the engine is less than the power consumed by the alternator, the UCH reduces the PR075 Alternator setpoint
voltage.
The battery warning light will flash if a low battery charge is detected (no-load voltage less than 12.2 V: voltage
measured during technical use) for the first 12 miles (20 kms), then the warning light stops flashing. Also, the magic
eye of the battery (the hydrometer) is black.
–Access - Security function (see 82D, Access - Security, Role of components).
–Heating and manual air conditioning function (see 61A, Heating, Role of components and 62C, Manual air
conditioning, Role of components).
–Wiping function (see 85A, Washing wiping, Role of components).
–Lighting function (see 80D, Lighting, Role of components). Note:
At the time of user activation, if the mileage is less than 12 miles (20 kms) the charge status is used to display a
warning: this ensures that vehicles are delivered with correct batteries.
87B-11
MR-413-X44-87B000$192.mif
V5
UCH
Vdiag No.: 44PASSENGER COMPARTMENT CONNECTION UNIT
Fault finding - Role of components87B
Functions managed by the different UCH ranges on the New Twingo:
* CPE: Electric central door locking
* CAR: Automatic locking when drivingL1
Entry levelL2
Mid-rangeL3
Top of the
range
UCH reprogrammingXX X
Multiplex connectionXX X
Fault findingXX X
Access - Protection X X X
Transponder keyX
Transponder and radiofrequency keyXX
Engine immobiliserXX X
+ Accessories feed controlXX X
Alarm management (predisposition)XX
Locking and unlocking using electric central door locking buttonXX
DeadlockingX
Locking when driving (CAR*)XX
Automatic unlocking (in the event of impact)XX
Engine thermal protectionXX X
Automatic re-lockingXX
One-touch electric windowsX
Tailgate electric lockXX X
Tailgate opening switchXX X
Tailgate locking switch (with key)X
Air conditioning
Electric heated rear screen managementXX X
Air conditioning request managementXX
Automatic climate control management (via CAN network)XX
External temperature managementXX
87B-13
MR-413-X44-87B000$240.mif
V5
87B
PASSENGER COMPARTMENT CONNECTION UNIT
Fault finding - Replacement of components
When replacing the UCH (see MR 411, Mechanical systems, 87B, Passenger compartment connection unit).
If replacing the computer, carry out the programming and configuration operations described (see configurations
and programming).
The order of programming and configuration operations is as follows:
1 - Write the VIN, using command VP004 Write VIN.
2 - Program the UCH using command SC004 UCH programming.
3 - Configuration of the UCH (in the Configuration and programming menu) using the following commands:
CF031 Calibration,
CF019 Type of heating and air conditioning system,
CF028 Engine type,
CF171 Temperature display,
CF029 External temperature sensor,
CF173 One-touch windows/sunroof (SR)*.
CF032 See-me-home lighting,
CF021 Front fog lights,
CF014 Daytime running lights
CF193 Automatic headlight function,
CF194 Automatic wiping function,
CF035 Rain/light sensor,
CF191 Wiper intermittent speed ring,
CF024 Hazard warning lights activated by ABS,
CF108 Locking via the RAID,
CF009 Deadlocking,
CF192 Central door locking,
CF195 Type of key,
CF229 Alarm.
4 - Key allocation, using command SC015 Key allocation.
5 - Configuration of the multiplex network is used to define (in the UCH) the different computers present and which
support fault finding on the multiplex network.
* TO: Sunroof.
MR-413-X44-87B000$240.mif
UCH
Vdiag No.: 44
87B-22
MR-413-X44-87B000$288.mif
V5
UCH
Vdiag No.: 44PASSENGER COMPARTMENT CONNECTION UNIT
Fault finding - Configurations and programming87B
UCH CONFIGURATIONS
List of individual configurations available on the diagnostic tool with the associated configuration reading.
* SR: Sunroof.
*RF: radio frequencyConfigurationConfiguration
readingName of configuration Choice of configuration
CF031 "Calibration",To be performed if replacing
the UCH.
CF019 LC013"Type of heating and air conditioning
system",HEATING/MANUAL/
AUTOMATIC
CF028 LC023 "Engine type",Configuration. 1 (K9K)
Configuration. 2 (D7F/D4F
without air conditioning)
Configuration. 3 (other engine)
CF171 LC067 "Temperature display"WITH/WITHOUT
CF029 LC002 "Exterior temperature sensor",WITH/WITHOUT
CF173 LC070 "One-touch windows/SR*",WITH/WITHOUT
CF032 LC025 "See-me-home lighting",WITH/WITHOUT
CF021 LC015 "Front fog lights"WITH/WITHOUT
CF014 LC008 "Daytime running lights",WITH/WITHOUT
CF193 LC095 "Automatic headlighting function",WITH/WITHOUT
CF194 LC096 "Automatic wiping function",WITH/WITHOUT
CF035 LC044 "Rain/light sensor", PRESENT/ABSENT
CF191 LC094 "Wiper intermittent speed ring",WITH/WITHOUT
CF024 LC018"Hazard warning lights switched on by
ABS",WITH/WITHOUT
CF108 LC040 "Automatic locking when driving",WITH/WITHOUT
CF009 LC003 "Deadlocking",WITH/WITHOUT
CF192 LC093 "Central door locking",WITH/WITHOUT
CF195 LC097 "Type of key". STANDARD/RF*
CF229 LC126 "Alarm".WITH/WITHOUT