sensor CITROEN CX 1988 Service Manual

PROTECTION OF THE ELECTRICAL COMPONENTS
PRECAUTIONS TO BE TAKEN WHEN CARRYING OUT AN OPERATION ON THE VEHICLE
It is essential to avoid actrons which may damage the electrical or the electronic equipment or create a short circuit
(wrth subsequent risk of fire or accident).
Battery:
a) First disconnect cable clamp from the battery negative terminal, earthed, then from the positive post.
b 1 Before tightening the negative clamp to the battery (the negative lead should be connected last), ensure that there
is no short circuit (bright sparks or arcs).
Small sparks may occur due to the interior lamp (door open), door locking device, clock or components having
remained in operation.
c 1 Make sure that the terminals are properly connected. Clamps and terminals should be clean and correctly tightened.
d ) When recharging the battery, disconnect the two clamps first.
e) Do not reverse the negative and positive clamps on the battery. (This could destroy the alternator diodes).
Fuses:
a 1 Fit the correct type of fuses: use the fuses specified for the protected devices
b 1 Take the added accessories and the functions into consideration.
Charging circuit:
,a 1 Do not run the alternator unless it is connected to the battery. Do not disconnect the battery when the alternator
is rotating.
b 1 Ensure that the regulator is correctly earthed.
c ) Do not interchange the leads connected to the regulator, (charge detection warning lamp and excitation are specific).
d ) Do not connect a suppressor capacitor to the regulator without taking precautions or following proper
instructions.
e 1 Do not use an electric welding equipment on the vehicle without having first disconnected the alternator, the regula-
tor and the battery (insulate the two terminals).
f 1 Do not R check )) the operation of an alternator by short circuiting the positive and ground terminals, which may
destroy the diodes.
Starting the engine:
Do not use a booster or a 24-volt battery. Only use a correctly charged 12-volt battery (a higher capacity battery may
be utilised). Otherwise, risk of deterioration of the ignition module or any other electronic control units. If the starter
is needed for starting the engine, without running it, it is necessary to disconnect datum and flywheel sensors on the
All Electronic Ignition, or the primary lead of the coil on any other type of ignition.
Ignition:
a 1 Do not connect a suppressor capacitor to the negative terminal of the coil.
b 1 Do not operate the module if its radiator is not connected to the earth.
c 1 Fit the radio suppressor capacitors recommended by the factory.
d 1 Never operate the ignition system while the HT circuit is open. Connect the HT leads to earth
e) Only use rev. counter having a HT sensor, (never puncture HT leads).
0.1. bulb:
a) Never replace a 01. bulb with the headlamp switched on. If the headlamps have been in use, allow them to cool down.
b) Do not touch a 0.1. bulb with bare fingers. Any fingerprints must be cleaned with soapy water and the bulb dried
with a dry lint-free cloth.
Checks :
a) Preferably use a high resistance (> 10 k Q VI voltmeter or a battery-operated ohm-meter
b) Take care not to use instruments taking their power from the mains.
Electronic components:
a) Avoid overvoltages due to a badly insulated charger, electric arcing or connections to the coil.
The units such as regulator, ignition module, tachometer, windscreen wiper timer, flasher unit, clock, radio, oil gauge
unit, door lock control unit, etc. comprising electronic components may be deteriorated.
b) The electronic components should not be placed or operated under a temperature exceeding 80°C.
c) Always switch off instruments or electronic control units before connecting or disconnecting them.
‘

RECOMMENDED PRODUCTS
IV - GREASES AND LUBRICANTS
PRODUCT
USE AND SPECIAL FEATURES AND SYMBOL MARK SUPPLIER
R.P. No.
High adhesive grease: 95 615 129 R.P.D.
- Intended mainly for drive-shaft lubrication.
GRAISSE 1495 Gl MOLY DAL
- Can be used for mechanisms working under difficult
conditions (high pressures, splashed water). MOLYKOTE
LONGTERM 2 DOW-CORNING
Grease resisting high temperatures:
GRIPCOTT AF G2
- For exhaust manifold ball-joints. MOLYDAL
Lubricant for parts working under difficult
conditions:
HI LUB-HTC G3 FRAM ET
- Splashed water, high pressure and temperature.
Grease resisting high temperatures:
- To lubricate the threaded spark plugs fitted to the NO-BIND G4 CURTY *
cylinder head.
Multifunctional lubricant:
M.O.
G5
- Molybdenum disulfide-base product. TEROSON
Multifunctional grease:
- For routine works. TOTAL MULTIS G6 TOTAL C.F.R.
Special grease: PROBA. 270
ALTEMP G7 R.P.D.
- Designed for anti-roll bar bearings.
79.01973.067
Animal grease:
- Tallow. GB
Special grease: ESSO
- To be used for fitting the road wheel sensors of the NORVA G9 R.P.D.
anti-locking brake system. 275
8531

REMOVING AND REFITTING
THE ENGINE/GEARBOX ASSEMBLY
- 2.5 LITRE CX WITH PETROL INJECTION -
REMOVAL
Support the car on stands horizontally, Fig. I using
the three stands 6602-T, in order to facilitate the
removal of the power unit assembly and to reposition
it more easily on the stands.
Depressurize the hydraulic system.
Drain the brake accumulator.
Set the height control to the “low” position
Remove:
- the battery,
- the bonnet,
- the front wheel,
- the spare wheel
- the protection plate located under the spare wheel,
Drain the cooling circuit via the drain hose of the
radiator.
Take off the crankcase drain plug (I 1, Fig. II.
Remove the drive-shafts:
(Refer to Op @ MA.372. l/l)
Uncouple: hoses (6) and (71, Fig. IV (protecting the
alternator from water entry at “a”).
Disconnect the engine cooling fan thermal switch.
Remove the engine heat sink.
Extract, Fig. Ill:
- the screws that secure horn (2) support, passing
through the wheelarch,
- the wheelarch lining. Disconnect:
- wiring harnesses (3) from the battery positive lead,
Fig. Ill,
- the ground cable from the gearbox,
- the wiring harness from the reversing lamp switch.
Remove, Fig. Ill:
- the pressure regulator accumulator,
- pipe (4) between pressure regulator and brake accu-
mulator.
Vehicle with air conditioning option:
- the belt protective cover,
- the air conditioning compressor drive belt
Uncouple:
- the air intake casing position accelerator cable,
- the high pressure pump rubber suction pipe,
- the high pressure pump outlet pipe (5) and its attach-
ment, Fig. Ill.
Disconnect: Fig. V
- the throttle spindle switch (IO),
- knock sensor (14).
Uncouple: Fig. V
- pressure sensor pipe(91,
- supplementary air pipe (I I),
- cylinderhead cover pipe (I 21,
- breather pipe (8).
Remove suction pipe (I 3) situated between the flow-
meter and the turbocharger or between the flowme-
ter and the inlet manifold.

- pressure regulator- and compressor holder nuts (1 )
(a//- condit/oning option).
- all the sfirms,
and put them rn place of the battery.
Uncouple the exhaust systern.
Normally aspirated engine with E. F. I..
Remove the 4 exhaust pipe nuts.
Turbo with E./Y/., Fig. II and 111
Remove:
- screw (2) and shims (31,
- flexrble pipe screws (7),
- nuts and spacers (4).
Release exhaust pipe (8) downwards.
Remove nuts (5) and flexible pipe (6). - adtustrng nuts (91,
- clutch control support screws (I 0).
Uncouple the power take off with double outlet,
Fig. V.
Fully loosen screw i 121, then retrghten it by two turns
to prevent the speedometer drive guide from being
pushed out.
Disengage the twin outlet power take off ( 1 1).
Remove oil gauge i 13).
Uncouple, Fig. V:
- heater hoses (I 6) and (I 71,
- fast idle air duct (I 5),
- petrol supply pipe (181,
- petrol return pipe (14).
Disconnect, Fig. VII:
- connectors (201,
- sensors (221,
- coils and suppressors (I 9),
- gear shift link rods (21 ).

le up the exhaust system. econnect, Fig. IV and V:
- connectors 11 I),
turaily aspirated engines w/th EN, fitted with
seals:
Tighten the flange to 1.6 mda
On the turbocharged engines with EH, fitted with
NEW nuts and seals:
Refit: Fig. I and II, - sensor (12) (with biue /dent mark),
- sensor (13) (with no ident mark),
- HT coil 191 cyls 1 and 4 (with yellow /dent mark),
HT coil i IO) cyls 2 and 3 (w/t/r fro markl,
- the suppressors,
- the reversing larnp switch wrring harness,
- the throttle spindle switch (141,
- knock sensor (I 8).
- flexible pipe (2) to the pressure release valve outlet,
- exhaust pipe (4) to the turbo, screws (31, distance
pieces (51,
- screw (6) and adjusting shims.
There should be a 5 mm clearance at least between
the exhaust pipe and the engine crankcase. Recouple, Fig. V and VI:
- the water hoses,
- air circurt pipes (151, (161, (17). (20) and (211,
- petrol circuit pipes (I 9),
- gear shift link rods,
- the accelerator cable.
Tighten, Fig. I and II:
- turbocharger nuts fin the correct sequence), Fig. II,
- flexible hose (2) screws (3) and nuts (I 1 to
2.5 mdaN,
- screw (6) to 5 mdaN. Fit:
- the driveshafts,
(See Op. @ MA 372-l/11
- the radiator,
- the bonnet,
- the battery,
Refit: Fig. Ill
- the pressure regulator and compressor holder (air
conditioning option) together with its shims; tigh-
ten nuts (7) to 5 mdaN. - the protection plate located under the spare
wheel.
Check the oil levels. Top up if necessary.
Vehicles with air-conditioning: Fill up the cooling circuit (wrth the heater open) and
carry out the bleeding operation.
- the compressor belt and protection cover,
- the pressure regulator accumulator, fitted with a
NEW seal,
- the HP pump outlet pope, fitted with a NEW sea/
and its fastenings (8),
- the pipe situated between the pressure regulator
and the brake accumulator, fitted with NEWseals,
- the HP pump rubber suction pipe,
- the horn. (As per Op @ MA 230.0/l/.
Bleed the front brakes.
(Refer to Op. MA 453.0/l/.
Check the gear change.
Lower the vehicle to the ground.

“LE JETRONIC” ELECTRONIC FUEL
INJECTION SYSTEM
“LE Jetronic” system
The “LE Jetronic” IS a fuel injectiorl system which injects Intermittently petrol, at low pressure, into the inlet rnanifold
The main characteristic of the device IS to rneter drrectly the air drawn in by the engine, which is the only reference
for the fuel quantity to be injected. The fuel metering IS carried out by electro-magnetically triggered injectors. These
are under a constant fuel pressure.
The quantrty of fuel injected depends on how long the Injectors remain open. The duration of opening is optimally
determined for each engine operating phase by an electronic control unit, from data supplied by various electric
sensors.
The “LE Jetronic” device is composed of:
No.
COMPONENTS MADE BY REFERENCE
142 Electronic Control Unit (E.C. U.) BOSCH 0280 000 300
192 Throttle spindle switch cc 0280 120 301
280 Supplementary air control (C 0280 140 172
302 Flow meter ,, 0280 202 021
345 Electrovalve ,) 0280 141 011
576 Injector n 0280 150 254
683 Electrical fuel pump
)> 0580 464 008
731 Relay D 0280 230 009
841 Water temperature sensor D 0280 130 026
F Fuel filter N 0450 905 002
R Fuel regulator pressure ,) 0280 160 216

“LE Jetronic” system
The “LE Jetronic” is a fuel injection system whrch injects intermittently petrol, at low pressure, into the Inlet manrfold
The main characteristic of the device is to meter directly the air drawn In by the engine, which is the only reference
for the fuel quantity to be injected. The fuel metering is carried out by electro-magnetically triggered injectors. These
are under a constant fuel pressure.
The quantity of fuel injected depends on how long the injectors remain open. The duration of opening IS optimally
determined for each engine operating phase by an electronic control unit, from data supplied by various electric
sensors.
The “LE Jetronic” device is composed of:
No. COMPONENTS MADE BY REFERENCE
142 Electronic Control Unit (E.C.U.) BOSCH 0280 000 224
192 Throttle spindle switch 0
0280 120 313
280 Supplementary air control u
0280 140 178
302 Flow meter ,)
0280 202 061
345 Electrovalve ,,
0280 141 011
575 Cold start injector n
0280 170 409
576 Injector >,
0280 150 200
683 Electrical fuel
pump 1,
0580 464 008
731 Relay >,
0280 230 009
841 Coolant temperature sensor 1)
0280 130 026
870 Slow thermal switch ,>
0280 130 214
F Fuel filter ),
0450 905 002
R Pressure regulator ,)
0280 160 216

CHECKING AND ADJUSTING
THE INJECTION SYSTEM
III. - ADJUSTING THE ROTO-DIESEL INJECTION PUMP CONTROLS
DPC type pump from engine M 25/648, Fig. I
DPA type pump from engine M 25/660, Fig. II
Checking the fast-idle control
Ensure that lever (7) is against its stop, by pushing
it in the direction of arrow (-).
If not, adjust tension of cab/e by means of cable end
clamp (6). Complete tightening of cable using sheath
tensioner (41.
Checking the fast-idle control
Make sure that the cable is slack.
If not, check the operation of the thermal sensor (101
located on the water outlet duct: the cable must ope-
rate over a range of 6 mm between its “ENGINE
COLD” and “ENGINE WARM” positions.
Adjusting the accelerator control
Engine stopped:
Fully depress the accelerator pedal.
Check that lever (I) is against stop (2).
If not, move pin (3) of accelerator cable.
Make sure that, at idle, lever (I) is against stop (5).
Adjusting the anti-stalling device
Engine running:
Insert a 1.5 mm thick shim (DPC pump, Fig. I)
2 mm thick shim (DPA pump, Fig. II)
between lever (I) and stop-screw (5) at “b”.
Place a 3 mm dia. rod through the hole in lever (7)
at “a” by pushing STOP lever (9) outwards. Set the engine speed to:
800 t 50 rpm (DPC pump)
800 f 25 rpm (DPA pump)
by turning stop screw (5).
Remove the 3 mm dia. rod and the shim
Adjust the idling speed to:
800 + 25 rpm
by turning stop screw (8).
Checking the engine deceleration:
Accelerate the engine to 3.000 rpm, then release the
accelerator lever sharply.
- if the deceleration is too fast (engine often stalling),
unscrew stop-screw (5) by 114 turn,
- if the deceleration is too slow (poor engine braking),
screw up stop-screw (51 by l/4 turn.
In both cases, check the idling speed and adjust if
necessary.
If the malfunction continues to exist, carry out the
adjustments again.
Check the efficiency of the mechanically operated
STOP control (9).
Note: The setting figures are identical if the vehicle
is equipped with air-conditioning and the adjustments
are to be effected with the air-conditioning off.

SPECIFICATION AND SPECIAL FEATURES
OF THE AIR SUPPLY SYSTEM
Engines types 829.A5 and J6T.A500 are fitted with a device regulating the temperature of intake air.
This device has been designed for maintaining a minimum temperature of the air drawn into the carburettor
It consists of a thermal sensor and a vacuum capsule operating a flap. Thermal source
The thermal sensor is located in the pipe connecting the air filter to the inlet manifold of the carburettor
This bi-metal type thermostat, is subjected to the inlet air temperature
It controls the opening of valves allowing passage for a depression towards the capsule
This depression is picked up by a union having a calibrated orifice, fitted to the pipe connecting the oil breather
to the intake manifold of the carburettor, and by a T-shaped union situated near the carburettor base plate, so
as to have an action over the engine load.
The thermal sensor allows the depression to circulate when the temperature is below 15°C and stops it when the
temperature exceeds 25°C. Vacuum capsule.
The capsule, located in the inlet of the air filter, is subjected to the depression. When energised, it operates a flap
which lets the heated air coming from a tapping located on the exhaust shield enter. At rest, the flap lets intake
air coming from behind the grill enter.

GENERAL FEATURES
OF THE TRANSISTORISED IGNITION SYSTEM
TRANSISTORISED IGNITION
PRINCIPLE OF OPERATION
The plug spark is triggered by distributor (1) which comprises a coil located inside the field of a magnetic circuit
permanent magnet. The magnetic circuit has four fixed branches and four movable branches driven by the distribu-
tor shaft.
When the movable branches, in their rotation, come opposite the fixed ones, a variation of the magnetic field is
brought and current is induced into the sensor winding.
This current, in turn, triggers electronic module (2)
which builds up the current in ignition coil (3) primary winding
and then cuts it off, thus creating a high tension current in the coil secondary winding and triggering a spark from
the plug selected by the distributor rotor arm. IGNITION DISTRIBUTOR (I!
The advance curves are specific for each engine type
N: Distributor rpm
D = Vacuum Dl, in m.bars A:
Distributor degrees 02, in mm.hg
Pick-up coil resistance: 1100 Q sr 10% (990 to 1210 02)
Setting the distributor static timing on the engine is impossible owing to design.
A revolution of the distributor is required to create a variation of the magnetic field which will send a signal to the
module. Consequently, when fitting a distributor, place it in mid-slot; start the engine and adjust the distributor
by means of a timing light or a diagnosis console.
The duration and amplitude of the signal depend on the speed, therefore the DWELL ratio
is not significant.
The air gap between the branches is non-adjustable and it cannot be measured ELECTRONIC MODULE (2)
Intended to operate with the magnetically-triggered distributor.
Do not carry out a check with an ohmmeter since the results would not be significant.
Do not operate the module without cooling (aluminium plate heat sink and heat conductor grease).
The operation of the ignition system is possible with the engine stopped: - connect an earthed sparking plug to
the coil HT lead; short ” + 12 volts” pulses on module red lead (path 5) (with all leads connected, cap lifted) will
generate a spark from the plug: simulation of a signal from the distributor pick up).
Do not operate the module and coil without a plug and HT lead, (It could result in the module being destroyed). IGNITION COIL (3)
The coil must not be kept alive under 12 volts without its module (overheating).
The coil current flow is generated by the module which then reduces it, prior to cutting it off when the engine
ignition timing occurs.
Only use a rev. counter with a UT induction clip.