13B-12V4 MR-372-J84-13B000$020.mif
DIESEL INJECTION
Fault finding – System operation13B
DDCR INJECTION
Vdiag No.: 44, 48
Functions included
Air conditioning management assistance
For vehicles with air conditioning, the DDCR system can switch off the air conditioning under certain engine
operating conditions:
– when requested by the driver,
– when starting the engine,
– if the engine overheats (in order to reduce the power the engine has to supply),
– when the engine speed is kept at a very high level (to protect the compressor),
– during transition phases (e.g. under heavy acceleration when overtaking, anti-stalling and moving off strategies).
These conditions are only taken into account when they do not occur repeatedly, in order to prevent system
instabilities (erratic deactivations),
– when certain faults appear.
Cold loop air conditioning management
The air conditioning is the cold loop type and its management shared between several computers. The injection
computer is responsible for:
– managing demand for cold air according to the passenger compartment commands and the pressure value,
– determining the power absorbed by the compressor from the pressure,
– determining the fan unit commands according to vehicle speed and pressure.
The driver requests the air conditioning to be switched on by means of the ventilation selector coupled to a switch.
The cold air request is authorised or denied depending on the pressure measured. If this pressure is outside
the operating limits, the cold loop program is not activated.
Thermal regulation of the passenger compartment heating circuit
In a direct injection engine, fuel is injected directly into the combustion chamber. This leads to heat being lost
through the upper part of the engine and consequently, the cylinder head cooling circuit is smaller in size.
The effect of this is that the temperature of the coolant flowing through this circuit rises more slowly. However, this
coolant is also used by the passenger compartment heating system. In very cold conditions, it is therefore difficult to
achieve a comfortable passenger compartment temperature quickly.
To limit the time taken to warm up the system, air heating resistors, called RCHs, are fitted into the passenger
compartment heating circuit. The UCH decides whether the RCH are required, the UPC physically actuates
the RCH, and the injection computer determines whether to limit the power supplied to the RCH depending on
alternator charge, and also whether to disable them according to engine speed, load and vehicle speed. NOTE:
Fan unit actuation requests can be made by the injection computer, but these are sent on the CAN. These requests
depend on the air conditioning but also on the coolant temperature and vehicle speed.
13B-14V4 MR-372-J84-13B000$020.mif
DIESEL INJECTION
Fault finding – System operation13B
DDCR INJECTION
Vdiag No.: 44, 48
Temperature / emergency stop warning light
This indicator light is used both as an in-operation indicator light and as a system fault warning light. It illuminates for
3 seconds when the power is switched on (automatic test procedure controlled by the instrument panel)
Continuously lit: indicates engine overheating or a Level 2 fault.
– if the fault reaches a critical level, the injection cuts off automatically after several seconds.
– in the event of engine overheating, it is the driver's choice to stop the car or continue driving.
ACTIVATION PROGRAMMING OF THE INSTRUMENT PANEL WARNING LIGHTS
Orange SERVICE warning light (level 1)
This warning light comes on, accompanied by the faulty injection message.
The driver should have the repairs carried out as soon as possible.
Red STOP warning light (level 2)
This warning light comes on, accompanied by the faulty injection message.
The driver should have the repairs carried out as soon as possible.
Excess pollution OBD ORANGE warning light:
This warning light is used to alert the driver of any injection faults that could lead to excessive pollution, or if
the EOBD system has been deactivated. The injection computer requests illumination of the OBD warning light for
a present fault only after three consecutive driving cycles.
The 3 second visual inspection when the ignition is switched on (automatic test procedure managed by
the instrument panel) is carried out by the injection computer.
Faults that activate the OBD warning light
Associated
faultTitle Specification
DF010 EGR position sensor circuit CC.1 - CO.0
DF016 EGR control circuit CC.1
DF026 Cylinder 1 injector control circuit CO – CC
DF027 Cylinder 2 injector control circuit CO – CC
DF028 Cylinder 3 injector control circuit CO – CC
DF029 Cylinder 4 injector control circuit CO – CC
DF038 Computer 3. DEF
DF114 EGR solenoid valve circuit 4. DEF
