17B-15V7 MR-413-X44-17B000$030.mif
PETROL INJECTION
Fault finding – System operation17B
SIM 32 Injection
Program no.: D3
Vdiag No.: 44, 4C, 50
and 54
a. Nominal operation: two operating modes.
High temperature (low and medium load mode):
When the thermostat is not controlled, it opens at a temperature of around 108˚C (compared to 89˚C for a
conventional thermostat). This allows fuel consumption to be reduced at low engine loads due to an increase in the
engine operating temperature (as there is less friction).
Low temperature (high load mode):
When the engine is put under greater stress (high loads, high engine speeds), the computer supplies the resistor
(the thermostat is controlled) to obtain operating temperatures below 108˚C (typically between 75˚C and 90˚C).
When the thermostat is opening as expected, comfort and a suitable engine temperature are obtained.
Too avoid too many transitions, switching from one mode to another is subject to time delays (a few seconds to
switch from high temperature
→ low temperature mode and several minutes to switch from low temperature → high
temperature mode).
b. Defect operation: forcing of low temperature mode and/or limitation of engine torque.
Low temperature management is activated.
Low temperature defect mode is used when one of the following faults is present and stored. Defect mode is reset to
0 using the On/Off key. Note:
The engine management computer automatically controls the thermostat in certain conditions, with the
aim of protecting the engine:
–External temperature greater than approximately 30˚C,
–Recognition of accelerator pedal being fully depressed.
If there is a short circuit to earth or an open circuit on the thermostat (for example: a connector
disconnected, DF893 Controlled coolant thermostat circuit in CO: Open circuit), engine performance is
limited to protect the engine.
IMPORTANT:
–It is essential to follow the new procedure for bleeding the cooling circuit (see MR 392 and 385,
Mechanical systems, CLIO III and MODUS, 19A Cooling, Cooling circuit: Bleeding), to prevent major
overheating of the catalytic converter. This new procedure is applicable to D4F engines with
SIEMENS injection.
–Do not inverse the connections of the temperature sensor and the thermostat control when
dismantling or carrying out electrical tests (foolproofing by colour of connections).
