2000 FIAT MAREA coolant temperature

Fuel feed system
Engine Marea- Marea Weekend 9 ™
2000 range (Q)
10.
Control of idle speed
On the basis of signals from the rpm sensor and engine coolant temperature sensor, the injection control
unit controls the pressure governor and alters the injector control times to maintain idle speed stable at all
times.
Under certain conditions, the idle speed control unit also considers battery voltage.
Control of maximum speed limitation
According to rpm level, the injection control unit limits maximum speed by means of two types of inter­
vention:
- as maximum speed approaches, it reduces the amount of fuel injected to reduce line pressure;
- when maximum speed is exceeded, it inhibits operation of the auxiliary pump and injectors.
Control of maximum torque limitation
On the basis of rpm level, the injection control unit computes limit torque and maximum permitted fume
index parameters on the basis of predefined, stored maps.
It then corrects the above parameters using engine coolant temperature and car speed data. The resulting
values are then used to modulate the amount of fuel to be injected by adjusting the pressure regulator and
injectors.
Control of fuel temperature
The injection control uint is kept constantly informed of fuel temperature by a sensor on the return mani­
fold.
If fuel temperature exceeds a set value (about 110 °C), the control unit reduces line pressure by adjusting
the pressure governor, leaving injection times unaltered.
Control of coolant temperature
The injection control unit is constantly informed of coolant temperature by a sensor on the thermostat.
If engine coolant temperature or air conditioning fluid pressure exceeds certain levels, the control unit
performs the following actions:
- It reduces the amount of fuel injected by adjusting the pressure governor and injectors (power reduc­
tion);
- it controls the engine radiator cooling fan.
Control of glow plugs
The injection control unit controls operation of the glow plug preheating control unit to bring the tem­
perature in the combution chambers up to levels that promote fuel self-ignition and thus make start-up
easier.
The control unit controls the operation of the glow plug control unit for a certain time both before (pre­
heating) and after (postheating) engine start-up and also controls activation of the warning light on the
control panel.
Preheating, postheating and glow plug warning light activation times vary according to engine coolant
temperature.
4 Publication no. 506.763/24

Marea- Marea Weekend 9 ™
2000 range ©
Engine
Fuel feed system
10.
DIAGRAM SHOWING INFORMATION FLOW BETWEN THE INJECTION CONTROL UNIT AND
SENSORS/ACTUATORS
1. Auxiliary fuel pump
2. Variable geometry turbocharger control sole­
noid
3. Climate control compressor
4. Electric EGR valve
5. Rev counter
6. Engine radiator fan
7. Glow plug preheating control unit
8. Potentiometer on accelerator pedal
9. Brake and clutch pedal switches
10. Fuel pressure sensor
11. Intake air flow and temperature sensor (de-
bimeter)
12. Coolant temperature sensor
13. Fuel temperature sensor
14. Pressure relief sensor
15. Timing sensor
16. Rpm sensor
17. Vehicle speed signal
18. Battery
19. Four stage pressure switch
20. Fiat CODE control unit
21. Diagnostic socket
22. Fuel pressure regulator
23. Injectors
24. Throttle valve control solenoid
25. Glow plug preheating warning light
26. Injection system failure warning light
Copyright by Fiat Auto 1

Marea- Marea Weekend 9 ™
2000 range ©) Fuel feed system
Engine
10.
Compents of injection system wiring diagram
1. Vehicle speepd
2. Rev counter
3. Engine radiator fan low speed relay
4. Radiator fan high speed activation relay
5. Potentiometer on accelerator pedal
6. Timing sensor
7. Fuel pressure sensor
8. EGR system modulator solenoid
9. Fuel pressure regulator
10. Glow plug preheating warning light on control panel
11. Injection system failure warning light
12. Air conditioning system relay
13. Coolant temperature sensor
14. Rpm sensor
15. Fuel temperature sensor
16. Diagnostic socket
17. Fiat CODE control unit
18. Four stage pressure switch
19. Injection electronic control unit
20. Pressure relief sensor
21. 7.5A fuse protecting electronic injection system ( + 15 power supply from ignition switch)
22. 7.5A fuse protecting electronic injection system ( + 30 power supply from ignition switch)
23. Main injection system relay
24. 30A fuse protecting injection system
25. Auxiliary fuel pump relay
26. Glow plug preheating control unit
27. Intake air flow and temperature sensor (debimeter)
28. Brake pedal switch
29. Clutch pedal switch
30. Ignition switch
31. Battery
32. Inertia switch
33. Auxiliary fuel pump (submerged in tank)
34. 60A fuse protecting glow plug control unit
35. Cylinder no. 1 glow plug
36. Cylinder no. 2 glow plug
37. Cylinder no. 3 glow plug
38. Cylinder no. 4 glow plug
39. Cylinder no. 1 injector
40. Cylinder no. 2 injector
41. Cylinder no. 3 injector
42. Cylinder no. 4 injector
43. Throttle valve control solenoid
44. Variable geometry turbocharger control solenoid
45. Diesel filter heater relay
Copyright by Fiat Auto 9

Ma tea- Ma tea Weekend !@ ™
2000 range ©
Engine
Fuel feed system
10.
37 Not connected
38 Not connected
39 Not connected
40 Not connected
41 Not connected
42 Not connected
43 Not connected
44 Not connected
45 Not connected
46 Not connected
47 Engine rpm signal output
48 Diagnostic line k
49 Vehicle speed signal input
50 Not connected
51 Activation signal from 4-stage pressure switch
52 Activation signal from 3-stage pressure switch
53 Not connected
54 Not connected
55 Not connected
56 Not connected
57 Not connected
58 Key ON signal
59 Brake switch
60 Air conditioner activation request
61 Clutch switch
62 Glow plug diagnosis
63 Not connected
64 Not connected
65 Not connected
66 Not connected
67 Not connected
68 Not connected
69 Not connected
70 Not connected
71 Not connected
72 Not connected
73 Not connected
74 Not connected
75 Not connected
76 Accelerator pedal 1 earth
77 Accelerator pedal 1 signal
78 Accelerator pedal 1 power supply
79 Accelerator pedal 2 earth
80 Accelerator pedal 2 signal
81 Accelerator pedal 2 power supply
82 Diesel temperature sensor (pin 1)
83 Diesel temperature sensor (pin 2)
84 Coolant temperature sensor (pin 1)
85 Coolant temperature sensor (pin 2)
86 Air flow meter (pin 1)
87 Not connected
88 Air flow meter (pin 3)
89 Air flow meter (pin 5)
90 Fuel pressure sensor (pin 3)
91 Fuel pressure sensor (pin 2)
92 Fuel pressure sensor (pin 1)
93 Turbo pressure sensor (pin 1)
94 Turbo pressure sensor (pin 3)
95 Turbo pressure sensor (pin 2)
96 Not connected
97 Air flow meter (pin 4)
98 Not connected
99 RPM sensor (pin 1)
100 RPM sensor (pin 2)
101 RPM sensor (pin 3)
102 RPM sensor (pin 1)
103 Timing sensor (pin 2)
104 Timing sensor (pin 3)
105 Not connected
106 Not connected
107 Not connected
108 Fuel pressure regulator
109 Fuel pressure regulator
110 Not connected
111 Heater relay control Fuel filter
112 Not connected
113 Not connected
114 Cylinder 4 injector control
115 Not connected
116 Not connected
117 Cylinder 1 and 2 injector power supply
118 Cylinder 3 and 4 injector power supply
119 Cylinder 1 injector control
120 Cylinder 2 injector control
121 Cylinder 3 injector control
Copyright by Fiat Auto 11

Marea- Marea Weekend 9™
2000 range (§)
4F015XJ03
Engine
Fuel feed system
ijo.
ENGINE COOLANT TEMPERATURE
SENSOR
The sensor is fitted to the thermostat and
measures the temperature of the engine cool­
ant by means of an NTC thermistor with a
negative resistance coefficient.
Because the sensor is made using semicon­
ductor technology, the resistance falls if sen­
sor element temperature rises with increasing
coolant temperature.
Because resistance does not change in linear
manner, it is higher at low temperatures than
at high temperatures for the same temperature
increase.
1. NTC resistance
2. Sensor case
3. Electrical connector
FUEL TEMPERATURE
SENSOR
The sensor is fitted on the return manifold and
measures fuel temperature by means of an
NTC thermistor with a negative resistance co­
efficient.
Refer to the previous description of the cool­
ant temperature sensor for sensor operation.
FUEL PRESSURE SENSOR
The sensor is fitted in the middle of the fuel
delivery manifold (rail) and is responsible for
providing a return signal (feedback) to the
control unit in order to:
- adjust injection pressure;
- regulator injection duration.
Copyright by Fiat Auto 15

Engine Marea- Marea Weekend IP ™
Fuel feed system 2000 range o
10.
The EGR valve consists of:
- a Pierburg EGR solenoid (1) operated by engine management unit (2)
- a pipe from the exhaust manifold (4) (from which the exhaust gases flow)
- an air-water heat exchanger (3) (that lowers exhaust gas temperature)
- a pipe connected to throttle body (5) to which exhaust gases are admitted
4
Operation
With coolant temperature > 20°C and engine speeds between 800 and 3000 rpm, the engine management
unit controls the EGR solenoid by means of a square wave signal.
Changes in this signal allow the EGR coil to move a plunger and thus modulate the flow of exhaust gas
from the exhaust manifold to the intake manifold; this achieves two results:
- less air is taken in
- combustion temperature is lowered (due to the presence of inert gases), thus reducing the formation of
NOx (nitrogen oxides).
The engine management control unit is constantly informed of recirculation gas quantity via data from the
debimeter. If the intake of a given quantity of air (Qam) is required for a given rpm and the level sent by
the debimeter (Qar) is lower, the difference (Qgr) is the amount of gas recirculated.
Qam - Qar = Qgr
Qam = stored theoretical air quantity
Qar = actual air quantity
Qgr = recirculated gas quantity
An atmospheric pressure signal is used in controlling the EGR valve to detect when the car is being driven at
altitude. The recirculation gas quantity can then be reduced to prevent engine fumes.
28 Publication no. 506.763/24

Electrical equipment
Instrument panel
Marea-Marea Weekend
2000 range ©
55.
INSTRUMENT PANEL (excluding C.A.)
3 4 56789 10 11 12
21 20 1918 17 24 16 15 14 13 23 22
Front side
1. Fuel level gauge
2. Fuel reserve warning light
3. Speedometer
4. ABS failure warning light
5. Brake pad wear warning light
6. Left direction indicator warning light
7. Side lights warning light
8. Right direction indicator warning light
9. Main beam warning light
10. Low brake fluid level and handbrake ap-
plied/EBD system failure warning light
11. Rev counter
12. Engine coolant temperature gauge
13. Air Bag fault warning light
14. Brake light failure warning light
15. Doors open warning ilght
16. Trip counter/mileometer/outdoor tempera­
ture gauge
17. Low engine oil pressure warning light
18. Generator warning light
19 Injection system failure warning light
20. FIAT CODE system warning light
21. Heater plugs warning light
22. Seat belt warning light
23. Water in diesel filter warning light
24. EOBD warning light
14 Print rf 506.763/23

Marea- Marea Weekend
2000 range ©
Electrical equipment
Control module
55.
Wiring diagram
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n ti
O Mill
(*) JTD
A. Battery recharging warning light
B. Low engine oil pressure warning light
C. Left direction indicator warning light
D. Right direction indicator warning light
E. Side lights warning light
F. Instrument panel symbol lighting
G. Main beam warning light
H. Air Bag fault warning light
I. ABS failure warning light
J. Fuel reserve warning light
K. Fuel level gauge
L. FIAT CODE system warning light
M. Injection system failure warning light
M1. EOBD warning light
N. Water in diesel filter warning light
O. Heater plugs warning light
(**) TD 75 BHP
P. Seat belt warning light
Q. Brake pad wear warning light
R. Low brake fluid/handbrake on/EBD sys­
tem failure warning light
S. Brake light electronic control module
T. Brake light failure warning light
U. Doors open warning ilght
V. Speedometer
W. Rev counter
X. Engine coolant temperature gauge
Y. Electronic module
Z. Milometer - trip meter/outside tempera­
ture gauge
Z1 Odometer reset button
* Short-circuit plugs
Copyright by Fiat Auto 15