13B-18
MR-372-J84-13B050$195.mif
V17
Siemens Injection
SID301 and 304
Vdiag No.: 44-45-48-49-4D-4C
Program No.: B1 and B2DIESEL INJECTION
Fault finding – Function13B
MANAGEMENT OF PRE/POSTHEATING
Pre-postheating management involves controlling the heater plugs and the heater plugs indicator light on the
instrument panel (via the multiplex network). The heater plugs are activated by a preheating unit and the power is
provided by the battery.
When the ignition is switched on, the preheating period is activated; the indicator light comes on for a period
dependent on the battery voltage, atmospheric pressure and coolant temperature.
When the coolant temperature is below a certain threshold, a postheating function enables combustion stability,
and thereby engine operation, to be improved (reduction in unburned fuel and pollutant emissions).
MANAGEMENT OF ENGINE COOLANT TEMPERATURE
Engine cooling is guaranteed by a 2-speed fan assembly (GMV) (slow: GMV1 and fast: GMV2).
The injection computer requests the UPC to actuate them via the multiplex network.
To provide cooling:
– Engine running:
GMV1 is activated when the coolant temperature exceeds 96°C and is deactivated when it drops below 94°C.
GMV2 is activated when the coolant temperature exceeds 104°C and is deactivated when it drops below 102°C.
If the engine coolant temperature exceeds the warning threshold of 120°C, the injection computer requests the
instrument panel computer, via the multiplex network, to switch on the coolant temperature warning light. The
warning stops if the coolant temperature drops below 117 ° C.
If the engine coolant temperature exceeds the threshold of 11 5 ° C, the injection computer requests the UPC
computer, via the multiplex network, to switch off the air conditioning compressor so as to reduce the load on the
engine and attempt to limit its rise in temperature. The cut-off request is cancelled if the coolant temperature drops
below 110°C.
If a fault in the coolant temperature sensor circuit is detected, the injection computer requests that the coolant
temperature warning light is lit and that GMV2 is activated.
In addition to engine management, the injection computer centralises the cooling requirements for the air
conditioning and automatic gearbox/sequential gearbox functions (if fitted to the vehicle).
OTHER HOSTED FUNCTIONS
The other functions hosted by the computer are:
– Multiplex line.
– ADAC (Trip Computer).
– Trip Computer Display.
– Engine immobiliser.
– Airbag.
– Engine stop management.
– Starter management.
– Air conditioning.
– Cruise control/speed limiter.
