Page 177 of 2492
DIESEL EQUIPMENT
Pre-post-heating unit
13
LOCATION
Pre-post-heating unit (A)
This unit has two diodes to prevent the feeding of
the heater plugs when the air conditioning system
is operating and also has a CTN type air
temperature sensor.Coolant temperature sensor (1) (black connector)
99335R
BAir conditioning diaphragm control solenoid
valve on injection pump (fast idle)
CEGR control solenoid valve
98904R
SPECIFICATIONS
Temperature in °C ± 1Resistance Ω
252 610 to 2 990
80310 to 350
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Page 178 of 2492

DIESEL EQUIPMENT
Pre-post-heating unit
13
PRINCIPLE OF OPERATION FOR GAS PRE-POST-
HEATING
1. "Pre-heating" when the ignition is turned on
a) Variable pre-heating
The time period during which the warning
light is illuminated and the heater plugs
are fed is dependent on the coolant
temperature.3. "Post-heating" while the engine is running
Post-heating has two phases:
a) Fixed post-heating
After the engine has been started, the
plugs are for for 10 seconds.
b) Variable post-heating
Variable post-heating begins when fixed
post-heating has ended.
During this phase, the plugs are fed
alternately 1 - 3 and 2 - 4 depending on
the coolant temperature.
If the coolant temperature sensor is faulty,
the heater plugs are fed systematically for
14 seconds.
b) Fixed pre-heating
After the pre-heating warning light has
extinguished (variable pre-heating), the
plugs remain fed for up to 8 seconds
before the engine is started.
2. Starting
The plugs remain fed while the starter is
activated.If the coolant temperature sensor is faulty,
the heater plugs are fed systematically for
30 seconds.
Variable post-heating may be
interrupted:
- finally when the coolant temperature
> 65°C,
- momentarily when the unit receives
full load information (post-heating
microswitch opens) for more than 1
second ; post-heating begins again
when the engine returns to idle speed
or low load (microswitch closes).
DI1304
DI1305
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DIESEL EQUIPMENT
Pre-post-heating unit
13
FAULT FINDING
1. The pre-heating warning light does not operate
TEST SOLUTION
Earth the warning light output of connector (C) using
a 2 A fuse when the ignition is turned on (track B3).
• The fuse blows.
• The warning light does not illuminate.
• The warning light does illuminate.The warning light wiring in the instrument panel is in
short circuit. Repair the wiring.
The bulb is blown or the wiring is faulty.
Replace the bulb or repair the wiring.
Check:
- + battery on connector (A),
- + after ignition on connector (C),
- battery earth on connector (C).
If the feed is correct, replace the pre-post-heating
unit.
2. The pre-heating warning light only operates for a fraction of a second when the ignition is turned on.
TEST SOLUTION
Disconnect connector (B) and test the pre-heating:
• The warning light illuminates and there is a
voltage at the connector outputs (B).
• The warning light illuminates and there is no
voltage at the connector outputs (B).
• The pre-heating warning light illuminates for a
fraction of a second only.Check the plugs circuit. If it is correct, check and
replace the faulty plug(s).
Replace the pre-post-heating unit.
Check the before ignition feed to the pre-heating
unit.
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DIESEL EQUIPMENT
Pre-post-heating unit
13
FAULT FINDING
3. There is no fast idle when engine is cold (with air conditioning option)
TEST SOLUTION
Run the air conditioning.
• The fast idle operates
• The fast idle does not operate.Check the connections at the pre-post-heating unit
(connector C).
Ensure continuity between track C3 of connector (C)
and track 1 on the solenoid valve.
Replace the pre-post-heating unit (ensure the
warning light operates correctly when the ignition is
turned on).
If the fast idle solenoid valve opens the pneumatic
circuit, repair the circuit between the vacuum pump,
the solenoid valve and the diaphragm.
If the solenoid valve does not open the circuit,
measure the voltage between the 2 tracks on the
solenoid valve connector.
•12 volts
Replace the solenoid valve after testing the
connections.
•0 volt
Ensure the following continuities :
- between track 2 on the connector and earth,
- between track 1 and track C3 of the pre-post-
heating unit.
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Page 181 of 2492
DIESEL EQUIPMENT
Pre-post-heating unit
13
FAULT FINDING
4. Engine operation fault (difficulty in starting, idle speed unstable, noise...)
Check:
- the feed to the pre-post-heating unit :
•+before ignition at connector A.
•+after ignition on track B1 of connector C.
•earth on track C2 of connector C.
- at the pump connector, the resistance of the ALFB solenoid valve (between earth and track
A1) : 7Ω ± 0.5,
- the coherence of the temperature reading given by the coolant temperature sensor,
Temperature (°C) 25 80
Resistance (Ω) 2 610 to 2 990 310 to 350
- the adjustment and operation of the post-heating microswitch,
- the coherence of the open or closed status of the altimetric capsule switch according to the altimetric
pressure of the test site (the switch should be closed for a pressure > 925 ± 20 mbars).
If the fault persists carry out a complete re-adjustment of the pump.
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Page 182 of 2492
DI1306
DIESEL EQUIPMENT
Injector holder - heater plug
13
94952R1
1 + 2Injector holder assembly.
3Seal between the injector holder assembly
and the cylinder head.
4Flame arresting washer.
5Injector protector.
The injector holder assembly is screwed into the
cylinder head.
In order to remove the injector high pressure
pipes, use wrench B.Vi. 868 . To remove the
injector holder assembly, use the 27 mm long
socketMot. 997.
The following tightening torques must be
observed:
- lower section (2) on upper section (1) of the
injector holder : 7 ± 1 daN.m,
- injector holder on cylinder head: 7 ± 1 daN.m.
Each time an injector holder is removed, the
copper seal and the flame arresting washer must
be renewed.
SPECIFICATIONS
Injector holder (A)
Position of the flame arresting washer
Injector nose
To pre-combustion chamber
Heater plug (B)
Current: 15A after 8 seconds heating
Tightening torque : 2 daN.m
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Page 183 of 2492
DIESEL EQUIPMENT
Fuel filter
13
LOCATION
Principle of the electric heater
The heater has heated studs. They are ceramic,
made from barium titanate which has a positive
temperature coefficient, meaning that its
resistance increases as its temperature increases.
99332R
1Fuel filter
2Electric heater
3Hand priming unit
The electric diesel fuel heater and the thermostat
are integral in the head of the filter.
DIAGRAM
PRJ99258
449Electric heater
450Diesel heating relay
597Engine fuse box
645Passenger compartment fuse box Operating temperature
Electrical circuit closes: 0°C
Electrical circuit opens: from 8°C
Heater power: 150 W
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Page 184 of 2492
99461R
DIESEL EQUIPMENT
Fuel filter
13
REMOVAL - REFITTING (Special notes)
To remove the filter assembly use tool Mot. 1311-
06 for the quick release unions.
When refitting, refit the quick release unions by
hand and ensure they click back together correctly
(two O rings ensure sealing).
99332S
13-38