sensor FORD SIERRA 1986 1.G Engine Electrical Systems Workshop Manual

Ignition timingLeaded petrolUnleaded petrol
(at idle with vacuum pipe disconnected)(4-star, 97 RON)(Premium, 95 RON)
Early “Economy” models (800 rpm - vacuum pipe connected) . . . . . . .16º BTDC12º BTDC
1.3 litre models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12º BTDC8º BTDC*
1.6 litre models with VV carburettor . . . . . . . . . . . . . . . . . . . . . . . . . . . .12º BTDC8º BTDC*
1.6 litre models with 2V carburettor . . . . . . . . . . . . . . . . . . . . . . . . . . . .10º BTDC6º BTDC†
1.8 litre SOHC models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10º BTDC6º BTDC†
1.8 litre CVH models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .ESC Hybrid controlled, no adjustment possible
2.0 litre carburettor models up to 1985 . . . . . . . . . . . . . . . . . . . . . . . . .8º BTDC4º BTDC*
2.0 litre carburettor models from 1985 (except P100) . . . . . . . . . . . . . .10º BTDC6º BTDC†
P100 models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6º BTDC2º BTDC†
2.0 litre fuel injection models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12º BTDC8º BTDC†
*Fill with leaded petrol (4-star, 97 RON) every 4th tankful
†Not all vehicles are suitable for continuous operation on unleaded petrol.
Spark plugs
Make and type:
All models except 1.8 CVH, CVH (R6A), 2.0 DOHC and P100 . . . . . . . .Champion RF7YCC or RF7YC
1.8 CVH engine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Champion RC7YCC or RC7YC
P100 model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Champion RF7YC or F7YC
1.6 and 1.8 CVH (R6A type) and 2.0 DOHC . . . . . . . . . . . . . . . . . . . . . .Champion RC7YCC
Electrode gap:
Champion F7YCC or RC7YCC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .0.8 mm (0.032 in)
Champion RF7YC, F7YC or RC7YC . . . . . . . . . . . . . . . . . . . . . . . . . . . .0.7 mm (0.028 in)
Note: The electrode gap above is the figure quoted by Champion for use with their recommended spark plugs. If plugs of any other type are fitted,
refer to their manufacturer’s gap recommendations.
HT leads
All SOHC models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Champion LS-09 or LS-10 boxed set
1.8 CVH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Champion LS-10 boxed set
1.6 and 1.8 CVH (R6A type) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Champion LS-30 boxed set
2.0 DOHC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Champion LS-29 boxed set
Maximum resistance per lead . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .30 000 ohms
Alternator
Type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Bosch, Lucas, Motorola, or Mitsubishi
Regulated output voltage at 4000 rpm (3 to 7 amp load) . . . . . . . . . . . .13.7 to 14.6 volts
Minimum brush length:
All alternator types except Motorola . . . . . . . . . . . . . . . . . . . . . . . . . .5.0 mm (0.20 in)
Motorola type alternators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4.0 mm (0.16 in)
Starter motor
Type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Pre-engaged; Bosch, Cajavec, Lucas, or Nippondenso
Minimum brush length:
All except Bosch long frame 1.1 kW and JF, and Nippondenso . . . .8.0 mm (0.32 in)
Bosch long frame 1.1 kW and JF, Nippondenso starter motors . . . .10.0 mm (0.40 in)
Battery charge condition:
Poor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12.5 volts
Normal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12.6 volts
Good . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12.7 volts
Torque wrench settingsNmlbf ft
Spark plugs:
SOHC models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20 to 2815 to 21
CVH models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18 to 3313 to 24
DOHC models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15 to 2111 to 15
Crankshaft speed/position sensor clamp bolt (ESC Hybrid system) . . .4 to 73 to 5
Crankshaft speed/position sensor screw (DOHC) . . . . . . . . . . . . . . . . .3 to 52 to 4
Camshaft sprocket bolt (CVH models) . . . . . . . . . . . . . . . . . . . . . . . . . .95 to 11570 to 85
Air charge temperature sensor (CVH-R6A and DOHC) . . . . . . . . . . . . .20 to 2515 to 18
Engine coolant temperature sensor (CVH-R6A and DOHC) . . . . . . . . . .20 to 2515 to 18
Fuel temperature sensor (DOHC injection) . . . . . . . . . . . . . . . . . . . . . . .8 to 116 to 8
Alternator adjustment bolt . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21 to 2815 to 20
Alternator mounting bolts:
With coloured patch on threads . . . . . . . . . . . . . . . . . . . . . . . . . . . . .41 to 5130 to 38
Without coloured patch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20 to 2515 to 18
5•2Engine electrical systems

General information
The electrical system is of the 12 volt
negative earth type, and consists of a 12 volt
battery, alternator with integral voltage
regulator, starter motor and related electrical
accessories, components and wiring. The
battery is of the low maintenance or
maintenance-free “sealed for life” type and is
charged by an alternator which is belt-driven
from the crankshaft pulley. The starter motor
is of the pre-engaged type, incorporating an
integral solenoid. On starting the solenoid
moves the drive pinion into engagement with
the flywheel ring gear before the starter motor
is energised. Once the engine has started, a
one-way clutch prevents the motor armature
being driven by the engine until the pinion
disengages from the flywheel.
The ignition system is responsible for
igniting the air/fuel mixture in each cylinder at
the correct moment in relation to engine
speed and load. A number of different ignition
systems are fitted to models within the
Sierra/P100 range, ranging from a basic
breakerless electronic system to a fully
integrated engine management system
controlling ignition and fuel injection systems.
The ignition system is based on feeding low
tension voltage from the battery to the coil
where it is converted to high tension voltage.
The high tension voltage is powerful enough
to jump the spark plug gap in the cylinders
many times a second under high compression
pressures, providing that the system is in
good condition. The low tension (or primary)
circuit consists of the battery, the lead to the
ignition switch, the lead from the ignition
switch to the low tension coil windings
(terminal + /15) and also to the supply terminal
on the electronic module, and the lead from
the low tension coil windings (terminal -/1) to
the control terminal on the electronic module.
The high tension (or secondary) circuit
consists of the high tension coil windings, the
HT (high tension) lead from the coil to the
distributor cap, the rotor arm, the HT leads to
the spark plugs, and the spark plugs.
The system functions in the following
manner. Current flowing through the low
tension coil windings produces a magnetic
field around the high tension windings. As the
engine rotates, a sensor produces an
electrical impulse which is amplified in the
electronic module and used to switch off the
low tension circuit.
The subsequent collapse of the magnetic
field over the high tension windings produces
high tension voltage which is then fed to the
relevant spark plug via the distributor cap and
rotor arm. The low tension circuit is
automatically switched on again by the
electronic module, to allow the magnetic field
to build up again before the firing of the next
spark plug. The ignition is advanced and
retarded automatically to ensure that thespark occurs at the correct instant in relation
to the engine speed and load.
To improve driveability during warm-up
conditions and to reduce exhaust emission
levels, a vacuum-operated,
temperature-sensitive spark control system is
fitted to certain vehicles.Inductive discharge system
This is the least sophisticated system fitted
to the Sierra/P100 range, and comprises a
breakerless distributor and an electronic
switching/amplifier module in addition to the
coil and spark plugs.
The electrical impulse which is required to
switch off the low tension circuit is generated
by a magnetic trigger coil in the distributor. A
trigger wheel rotates within a magnetic stator,
the magnetic field being provided by a
permanent magnet. The magnetic field across
the two poles (stator arm and trigger wheel) is
dependent on the air gap between the two
poles. When the air gap is at its minimum, the
trigger wheel arm is directly opposite the
stator arm, and this is the trigger point. As the
magnetic flux between the stator arm and
trigger wheel varies, a voltage is induced in
the trigger coil mounted below the trigger
wheel, and this voltage is sensed and then
amplified by the electronic module and used
to switch off the low tension circuit. There is
one trigger wheel arm and one stator arm for
each cylinder (4).
The ignition advance is a function of the
distributor and is controlled both mechanically
and by a vacuum operated system. The
mechanical governor mechanism consists of
two weights which move out from the
distributor shaft as the engine speed rises due
to centrifugal force. As they move outwards,
they rotate the trigger wheel relative to the
distributor shaft and so advance the spark.
The weights are held in position by two light
springs and it is the tension of the springs
which is largely responsible for correct spark
advancement.
The vacuum control consists of a
diaphragm, one side of which is connected
via a small bore hose to the carburettor or
inlet manifold and the other side to the
distributor. Depression in the inlet manifold
and/or carburettor, which varies with engine
speed and throttle position, causes the
diaphragm to move, so moving the baseplate
and advancing or retarding the spark. A fine
degree of control is achieved by a spring in
the diaphragm assembly.
ESC (Electronic Spark Control) system
This system is only fitted to early
“Economy” models, and comprises a “Hall
effect” distributor, and an ESC module, in
addition to the coil and spark plugs.
The electrical impulse which is required to
switch off the low tension circuit is generated
by a sensor in the distributor. A trigger vane
rotates in the gap between a permanent
magnet and the sensor. The trigger vane has
four cut-outs, one for each cylinder. When
one of the trigger vane cut-outs is in line with
the sensor, magnetic flux can pass betweenthe magnet and the sensor. When a trigger
vane segment is in line with the sensor, the
magnetic flux is diverted through the trigger
vane away from the sensor. The sensor
senses the change in magnetic flux and sends
an impulse to the ESC module, which
switches off the low tension circuit.
The ignition advance is a function of the
ESC module and is controlled by vacuum. The
module is connected to the inlet manifold by a
vacuum pipe, and a transducer in the module
translates the vacuum signal into electrical
voltage. From the vacuum signal, the ESC
module determines engine load, and engine
speed is determined from the interval
between impulses supplied by the distributor
sensor. The module has a range of spark
advance settings stored in its memory, and a
suitable setting is selected for the relevant
engine speed and load. The degree of
advance can thus be constantly varied to suit
the prevailing engine speed and load
conditions.
ESC II (Electronic Spark Control II)
system
1.8 and 2.0 litre SOHC carburettor models
This system is a development of the ESC
system described previously in this Section,
but it enables more accurate control of engine
operation due to the inclusion of additional
monitoring features and control outputs.
Vehicles fitted with the ESC II system have an
electric inlet manifold heater which warms the
air/fuel mixture when the engine is cold, thus
reducing the amount of fuel enrichment
required, lowering fuel consumption and
improving driveability when the engine is cold.
The heater is operated by the ESC II module
receiving information on the engine temperature
from an engine coolant temperature sensor
mounted in the inlet manifold.
On 2.0 litre SOHC models, the ESC II
module operates a carburettor stepper motor
to control the engine idle speed. Using
information on engine speed, load,
temperature and throttle position (supplied by
a switch on the carburettor), the module
operates the stepper motor to maintain a
constant idle speed. On models equipped
with automatic transmission and/or air
conditioning, additional inputs are supplied to
the module to allow it to operate the stepper
motor to compensate for the additional engine
load imposed by the automatic
transmission/air conditioning. The ESC II
module also operates a “power hold” relay
which allows the stepper motor to function
briefly after the ignition has been switched off
in order to perform an anti-run-on and
manifold ventilation cycle.
2.0 litre DOHC carburettor models
A development of the ESC II system is used
to control the operation of the engine. The
module receives information from a
crankshaft speed/position sensor (similar to
that described for the ESC Hybrid system),
except that the sensor is activated by a
toothed disc on the rear of the crankshaft,
inside the cylinder block), and an engine
coolant temperature sensor.
1General information and
precautions
Engine electrical systems 5•3
5

The ignition advance is a function of the
ESC II module, and is controlled by vacuum.
The module is connected to the carburettor
by a vacuum pipe, and a transducer in the
module translates the vacuum signal into an
electrical voltage. From the vacuum signal,
the module determines engine load; engine
speed and temperature are determined from
the crankshaft speed/position sensor and the
engine coolant temperature sensor. The
module has a range of spark advance settings
stored in its memory, and a suitable setting is
selected for the relevant engine speed, load
and temperature. The degree of advance can
thus be constantly varied to suit the prevailing
engine speed and load conditions.
ESC Hybrid (Electronic Spark Control
Hybrid) system
This system is fitted to 1.8 CVH models,
and comprises various sensors and an ESC
Hybrid module, in addition to the coil and
spark plugs. The distributor serves purely to
distribute the HT voltage to the spark plugs
and consists simply of a rotor arm mounted
directly on the end of the camshaft, and a
distributor cap.
The electrical impulse which is required to
switch off the low tension circuit is generated
by a crankshaft speed/position sensor which
is activated by a toothed wheel on the
crankshaft. The toothed wheel has 35 equally
spaced teeth with a gap in the 36th position.
The gap is used by the sensor to determine
the crankshaft position relative to TDC (top
dead centre) of No 1 piston.
Engine load information is supplied to the
ESC Hybrid module by a vacuum transducer
within the module which is connected to the
inlet manifold by a vacuum pipe. Additional
inputs are supplied by an inlet
manifold-mounted engine coolant temperature
sensor, and an air charge temperature sensor
mounted in the base of the air cleaner. The
module selects the optimum ignition advance
setting based on the information received from
the various sensors. The degree of advance
can thus be constantly varied to suit the
prevailing engine conditions.
In addition to the ignition circuit, the module
also controls an electric choke heater, and a
solenoid valve which in turn controls a throttle
damper on the carburettor. The electric choke
heater is operated by the module using
information supplied by the engine coolant
temperature sensor. The heater is used to
slow down the rate at which the choke comes
off, thereby improving driveability and overall
fuel consumption when the engine is cold. The
solenoid valve controls the vacuum supply to
the carburettor throttle damper. The throttle
damper prevents sudden closing of the throttle
during deceleration, thus maintaining
combustion of the air/fuel mixture which
reduces harmful exhaust gas emissions.
Note that there is no provision for
adjustment of ignition timing with the ESC
Hybrid system.
EEC IV (Electronic Engine Control IV)
system
2.0 litre SOHC fuel injection models
This system controls both the ignition and
fuel injection systems. The EEC IV module
receives information from a “Hall effect”
distributor sensor (similar to that described
previously in this Section for the ESC system),
an engine coolant temperature sensor
mounted in the inlet manifold, a throttle
position sensor, and an air flow meter.
Additionally, on models equipped with
automatic transmission and/or air
conditioning, additional inputs are supplied to
the module to allow it to raise the idle speed
to compensate for the additional engine load
imposed by the automatic transmission/air
conditioning. The module provides outputs to
control the fuel pump, fuel injectors, idle
speed, and ignition circuit. Using the inputs
from the various sensors, the EEC IV module
computes the optimum ignition advance, and
fuel injector pulse duration to suit the
prevailing engine conditions. This system
gives very accurate control of the engine
under all conditions, improving fuel
consumption and driveability, and reducing
exhaust gas emissions. A “limited operation
strategy” (LOS) means that the vehicle is still
driveable, albeit at reduced power and
efficiency, in the event of a failure in the
module or its sensors.
2.0 litre DOHC fuel injection models
A development of the EEC IV system is
used to control both the ignition and fuel
injection systems. The module receives
information from a crankshaft speed/position
sensor (similar to that described for the ESC
Hybrid system), except that the sensor is
activated by a toothed disc on the rear of the
crankshaft, inside the cylinder block), a
throttle position sensor, an engine coolant
temperature sensor, a fuel temperature
sensor, an air charge temperature sensor, a
manifold absolute pressure (MAP) sensor, and
a vehicle speed sensor (mounted on the
gearbox). Additionally, on models with a
catalytic converter, an additional input is
supplied to the EEC IV module from an
exhaust gas oxygen (HEGO) sensor. On
models with automatic transmission,
additional sensors are fitted to the
transmission, to inform the EEC IV module
when the transmission is in neutral, and when
the kickdown is being operated.
The module provides outputs to control the
fuel pump, fuel injectors, idle speed, ignition
system and automatic transmission.
Additionally, on models with air conditioning,
the EEC IV module disengages the air
conditioning compressor clutch when starting
the engine, and when the engine is suddenly
accelerated. On models fitted with a catalytic
converter, the EEC IV module also controls
the carbon canister-purge solenoid valve.
Using the inputs from the various sensors,
the EEC IV module computes the optimum
ignition advance, and fuel injector pulse
duration to suit the prevailing engine
conditions. A “limited operation strategy” (LOS)means that the vehicle is still driveable, albeit at
reduced power and efficiency, in the event of a
failure in the module or one of its sensors.
1.6 litre and 1.8 litre (R6A type) CVH models
A development of the EEC IV system is
used to control both the ignition and fuel
injection systems. A fully electronic
Distributorless Ignition System (DIS) is fitted,
replacing the mechanical distribution of high
tension voltage (by a rotating distributor) with
“static” solid-state electronic components.
The system selects the most appropriate
ignition advance setting for the prevailing
engine operating conditions from a three-
dimensional map of values stored in the EEC
IV control module memory. The module
selects the appropriate advance value
according to information supplied on engine
load, speed, and operating temperature from
various sensors.
The EEC IV module receives information
from a crankshaft speed/position sensor
(similar to that described for the ESC Hybrid
system), except that on 1.6 litre engines, the
sensor is activated by a toothed disc on the
flywheel), a throttle position sensor, an engine
coolant temperature sensor, an air charge
temperature sensor, a manifold absolute
pressure (MAP) sensor, a vehicle speed
sensor (mounted on the gearbox), and an
exhaust gas oxygen sensor.
The module provides outputs to control the
fuel pump, fuel injector, throttle valve control
motor, pulse-air control solenoid, carbon
canister purge solenoid (where applicable),
and the ignition system.
Using the inputs from the various sensors,
the EEC IV module computes the optimum
ignition advance and fuel injector pulse dura-
tion to suit the prevailing engine conditions. A
“limited operation strategy” (LOS) means that
the vehicle will still be driveable, albeit at
reduced power and efficiency, in the event of
a failure in the module or one of its sensors.
Precautions
General
It is necessary to take extra care when
working on the electrical system to avoid
damage to semi-conductor devices (diodes
and transistors), and to avoid the risk of
personal injury. In addition to the precautions
given in the “Safety first!” Section at the
beginning of this manual, take note of the
following points when working on the system.
Always remove rings, watches, etc before
working on the electrical system. Even with
the battery disconnected, capacitive
discharge could occur if a component live
terminal is earthed through a metal object.
This could cause a shock or nasty burn.
Do not reverse the battery connections.
Components such as the alternator or any
other having semi-conductor circuitry could
be irreparably damaged.
If the engine is being started using jump
leads and a slave battery, connect the
batteries positive to positive and negative to
negative. This also applies when connecting a
battery charger.
5•4Engine electrical systems

sprocket bolt. Note that there is no need to
remove the timing belt or the sprockets.
Note: During production the engine ignition
timing is accurately set using a microwave
process, and sealant is applied to the
distributor clamp bolt. Removal of the
distributor should be avoided except where
excessive bearing wear has occurred due to
high mileage or during major engine overhaul.
A timing light will be required to check the
ignition timing after refitting the distributor.
All models except early
“Economy”
Removal
1Disconnect the battery negative lead.
2If necessary, identify each HT lead for
position, so that the leads can be refitted to
their correct cylinders, then disconnect the
leads from the spark plugs by pulling on the
connectors, not the leads.
3Where applicable, unclip the screening can
from the top of the distributor and disconnect
the earth strap. On fuel injection models,
disconnect the crankcase ventilation hose
from the air inlet hose, then disconnect the air
inlet hose from the inlet manifold and the
airflow meter for improved access.4Prise away the spring clips with a
screwdriver, or remove the two securing
screws, as applicable, and lift off the
distributor cap.
5Disconnect the HT lead from the coil by
pulling on the connector, not the lead, then
slide the HT lead holder from the clip on the
camshaft cover, and withdraw the distributor
cap.
6Where applicable, disconnect the vacuum
pipe from the vacuum advance unit on the
side of the distributor (see illustration).
7Using a suitable socket or spanner on the
crankshaft pulley bolt, turn the crankshaft to
bring No 1 cylinder to the firing point. If the
distributor cap is secured by clips, make sure
that the clips stay clear of the distributormoving parts. No 1 cylinder is at the firing
point when:
a)The relevant timing marks are in
alignment.
b)The tip of the rotor arm is pointing to the
position occupied by the No 1 cylinder HT
lead terminal in the distributor cap. Note
that the position of No 1 HT lead terminal
is identified by a pip or a number “1”
c)On Lucas distributors, the cut-out in the
trigger vane is aligned with the sensor
(see illustration)
d)On Bosch distributors, the tip of the rotor
arm is aligned with the scribed line on the
distributor body (where applicable,
remove rotor arm and dust cover, then
refit rotor arm to check alignment with
scribed line) (see illustration)
e)On Motorcraft distributors, the tip of the
rotor arm is aligned with a notch in the
distributor body. Mark the relevant notch
(there may be several) for reference when
refitting. Also, the leading edge of one of
the trigger vane segments is aligned with
the rib on the sensor (remove the two
securing screws and lift off the rotor arm
to view the trigger vane and sensor) (see
illustration).
8Disconnect the distributor wiring plug,
where applicable depressing the locking
tab(s). Pull on the plug, not the wiring (see
illustration).
9Make alignment marks between the
distributor body and the cylinder block.
10Scrape the sealant from the distributor
clamp bolt, then unscrew and remove the bolt
and clamp (see illustration).
11Withdraw the distributor from the cylinder
block. As the distributor is removed, the rotor
arm will turn clockwise due to the skew gear
drive. Note the new position of the rotor arm
relative to the distributor body, if necessary
making an alignment mark (some distributors
already have an alignment mark).
12Check the distributor spindle for
excessive side-to-side movement. If evident,
the distributor must be renewed, as the only
spares available are the cap, rotor arm,
module (where applicable), and driveshaft
O-ring (see illustration).
15Distributor (OHC models) -
removal and refitting
5•16Engine electrical systems
14.9 Removing the rotor housing
15.7a Lucas distributor showing trigger
vane position No 1 cylinder at firing point
A Trigger vane cut
-outB Sensor
15.8 Disconnecting distributor wiring plug
- Bosch distributor15.7c Trigger vane segment leading edge
aligned with sensor rib - Motorcraft
distributor15.7b Rotor arm tip aligned with scribed
line on distributor body - Bosch distributor
15.6 Disconnecting vacuum pipe from
vacuum advance unit - Bosch distributor

EEC IV modules
Ignition module
Models up to 1987
Note: When refitting, the rear face of the
module must be coated with heat sink
compound. Refer to a Ford dealer for advice if
necessary.
12The module is mounted on the distributor
body.
13Disconnect the distributor wiring plug by
depressing the locking tabs. Pull on the plug,
not the wiring.
14Remove the two securing screws from the
module, then slide the module downwards
and withdraw it (see illustration).
15Refitting is a reversal of removal, but the
rear face of the module must be coated with
heat sink compound. Do not force the module
into position, as damage to the electrical
contacts may result.
Models from 1987
16The module is mounted on the left-hand
side of the engine compartment (see
illustration).
17Disconnect the module wiring plug by
depressing the locking tabs. Pull on the plug,
not the wiring.
18Remove the two securing screws and
withdraw the module from the engine
compartment.
19Refitting is a reversal of removal, but
ensure that the underside of the module and
the corresponding area of the body panel are
clean.
1.6 and 1.8 litre (R6A type) CVH models
20The ignition module is located at the front
right-hand side of the engine compartment. 21Disconnect the battery negative lead.
22Release the securing lug, and pull the
wiring plug from the module. Pull on the plug,
not on the wiring (see illustration).
23Remove the two securing screws, and
withdraw the module from the body panel.
24Refitting is a reversal of removal.
2.0 litre DOHC fuel injection models
25The ignition module is located on the left-
hand side of the engine compartment,
beneath the coil (see illustration).
26Disconnect the battery negative lead.
27Remove the two securing screws, and
withdraw the coil/ignition module heat shield.
28Release the locking lug and disconnect
the ignition module wiring plug. Pull on the
plug, not on the wiring.
29Remove the two securing screws, and
withdraw the module from the body panel.
30Refitting is a reversal of removal, ensuring
that the underside of the module and the
corresponding area of the body panel are clean.
Engine management module
All models except 1.6 and 1.8 litre CVH
(R6A type) and 2.0 litre DOHC fuel injection
31The module is located inside the
passenger compartment behind the
passenger side facia.
32Unclip the trim panel from below the
glovebox on models up to 1987, or from
above the glovebox on models from 1987.
33Unclip the module retainer and withdraw
the module.
34The wiring plug is secured by a screw
which is integral with the plug. Disconnect the
wiring plug and remove the module.35Refitting is a reversal of removal, noting
that the wiring plug will only fit in one position.
1.6 and 1.8 litre (R6A type) CVH models
36The module is located in the passenger
compartment, behind the glovebox.
37Disconnect the battery negative lead.
38Open the glovebox, and carefully pull it
from its retaining clips.
39Unclip and withdraw the module from its
retaining bracket (see illustration).
40The wiring plug is secured by a screw
which is integral with the plug. Disconnect the
wiring plug, and withdraw the module.
41Refitting is a reversal of removal, noting
that the wiring plug will only fit in one position.
2.0 litre DOHC fuel injection models
42For models up to 1990 refer to the first 5
paragraphs of this sub Section.
43For models from 1990 refer to the
procedure given for 1.6 and 1.8 litre CVH (R6A
type) engines.
Note: Procedures for removal and refitting of
the ignition system components and
electronic module are given elsewhere in the
relevant Sections of this Chapter.
1Disconnect the battery negative lead.
Engine coolant temperature
sensor
All models except 2.0 litre DOHC
2The sensor is located in the underside of
the inlet manifold.
19ESC II system components -
removal and refitting
5•20Engine electrical systems
18.14 EEC IV ignition module securing
screws (arrowed) - models up to 198718.22 Disconnecting the ignition module
wiring plug
19.4 Disconnect engine temperature
sensor wiring plug - ESC II system18.39 Engine management module
withdrawn from its mounting bracket18.25 Ignition module location (arrowed)
18.16 EEC IV ignition module - models
from 1987

3Partially drain the cooling system. There is no
need to remove the cylinder block drain plug.
4Disconnect the sensor wiring plug by
pulling on the plug, not the wiring (see
illustration).
5Unscrew the sensor from the inlet manifold
and remove it.
6Refitting is a reversal of removal. Fill the
cooling system.
2.0 litre DOHC models
7The sensor is located in the side of the inlet
manifold. The removal and refitting
procedures are as described for the 1.6 and
1.8 litre CVH (R6A type) engines in the
relevent Section of this Chapter.
Inlet manifold heater
Note: When refitting the heater, a new gasket
and O-ring must be used.
8Do not attempt to remove the heater while it
is hot.
9For improved access, remove the air
cleaner.
10Disconnect the wiring from the heater.
11Unscrew the three securing bolts and
remove the heater. Recover the gasket and
O-ring (see illustration).
12Refitting is a reversal of removal, using a
new gasket and O-ring, but be careful to
tighten the securing bolts evenly, otherwise
the heater may tilt and jam in its recess.
Carburettor stepper motor (2.0
litre models)
Note: Irregular idle is not necessarily caused by
a faulty or badly adjusted stepper motor. Good
electrical contact between the stepper motor
plunger and the adjusting screw (which from the
throttle position switch) is essential. Before
attempting adjustment or renewal of the motor,
try the effect of cleaning the plunger and
adjusting screw contact faces with abrasive
paper followed by switch cleaning fluid. Switch
cleaning fluid is available from electronic
component shops. Refer to the precautions in
Chapter 3 before proceeding.
13Remove the air cleaner.
14Depress the locking tab and disconnect
the stepper motor wiring plug. Pull on the
plug, not the wiring.
15Remove the four securing screws and
withdraw the stepper motor and bracket from
the carburettor.
16If desired, the stepper motor can be
separated from the bracket by removing thefour securing screws (see illustration).
17Commence refitting by securing the
stepper motor to the bracket, where
applicable.
18Refit the stepper motor and bracket to the
carburettor and secure with the four screws.
19Reconnect the wiring plug.
20Reconnect the air cleaner vacuum hose to
the inlet manifold, and position the air cleaner
to one side to allow access to the carburettor
and stepper motor.
21Reconnect the battery negative lead.
22Connect a tachometer to the engine in
accordance with the manufacturer’s
instructions.
23Start the engine, then check and if
necessary adjust the idle mixture.
24Ensure that all electrical loads are
switched off (headlamps, heater blower etc). If
the “idle speed adjustment” wire is earthed,
temporarily isolate it. Where applicable,
ensure that the automatic transmission gear
selector lever is in the “N” or “P” position.
25Accelerate the engine to a speed greater
than 2500 rpm, allow it to return to idle, then
repeat. Insert a feeler blade of 1.0 mm (0.04
in) thickness between the stepper motor
plunger and the adjusting screw (see
illustration). With the feeler blade in place the
engine speed should be 875 ±25 rpm.
26If adjustment is necessary, remove the
tamperproof cap from the adjusting screw
locknut. Slacken the locknut, then turn the
adjusting screw to achieve the correct enginespeed and tighten the locknut.
27Repeat the procedure given in paragraph
24 and check that the engine speed is still
correct. Readjust if necessary.
28Stop the engine, remove the feeler blade,
and disconnect the tachometer.
29Refit the air cleaner, ensuring that the
vacuum hose is securely connected. If the
“idle speed adjustment” wire was previously
earthed, reconnect it.
30Re-start and then stop the engine,
observing the movement of the stepper motor
plunger. Immediately after stopping the
engine, the plunger should move to the
“anti-dieselling” position, and after a few
seconds it should extend to the “vent
manifold/start” position (see illustration).
31Re-check and adjust the idle mixture.
32If necessary, refit the tamperproof caps to
the mixture adjustment screw and the stepper
motor adjustment screw locknut.
Crankshaft speed/position sensor
(2.0 litre DOHC models)
33The sensor is located at the right-hand
rear of the cylinder block behind the oil filter.
34Disconnect the battery negative lead.
35Access is most easily obtained from
underneath the vehicle. To improve access,
apply the handbrake, then jack up the front of
the vehicle and support it securely on axle
stands (see “Jacking and Vehicle Support”).
36Disconnect the wiring plug from the sensor.
37Remove the securing screw, and
withdraw the sensor from its location in the
cylinder block (see illustration).
Engine electrical systems 5•21
5
19.25 Carburettor stepper motor adjustment
- 2.0 litre models with ESC II system
A LocknutB Feeler blade
19.37 Removing the crankshaft
speed/position sensor (engine removed)
19.30 Carburettor stepper motor plunger
positions - 2.0 litre models with ESC II
system
A Vent manifold/start
B Anti-dieselling
C Normal idle
19.16 Carburettor stepper motor adjustment
- 2.0 litre models with ESC II system19.11 Removing inlet manifold heater -
ESC II system

38Before refitting the sensor, examine the
O-ring, and renew it if damaged or worn.
39Refitting is a reversal of removal, noting
the torque setting for the sensor screw.
Note: Procedures for removal and refitting of
the ignition system components and
electronic module are given elsewhere in the
relevant Sections of this Chapter.
1Disconnect the battery negative lead.
Crankshaft speed/position sensor
2The sensor is mounted in a bracket on the
timing cover.
3Disconnect the sensor wiring plug by
pulling on the plug, not the wiring (see
illustration).
4Slacken the sensor clamping screw and
slide the sensor from its bracket.
5Refitting is a reversal of removal, but the
clearance between the sensor and the
toothed wheel on the crankshaft must be set
at 1.0 mm (0.04 in). This can be achieved by
inserting a suitable length of wire or rod with a
diameter of 1.0 mm (0.04 in) between the
sensor and the toothed wheel (see
illustration). Do not overtighten the clamping
screw, as damage to the sensor may result.
Engine coolant temperature
sensor
6The sensor is located in the side of the inlet
manifold(see illustration).
7Partially drain the cooling system.
8Disconnect the sensor wiring plug by
pulling on the plug, not the wiring.
9Unscrew the sensor from the inlet manifold
and remove it.
10Refitting is a reversal of removal. Fill the
cooling system.
Air charge temperature sensor
11The sensor is located in the base of the air
cleaner.
12Remove the air cleaner.
13Disconnect the sensor wiring plug by
pulling on the plug, not the wiring (see
illustration).14Unscrew the sensor from the air cleaner
using a suitable spanner.
15Refitting is a reversal of removal. Refit the
air cleaner. Ensure that the vacuum hose is
securely connected.
Electric choke heater
16The electric choke heater is an integral
part of the automatic choke housing on the
carburettor. Removal and refitting of the
choke housing is covered in Chapter 4.
17The operation of the electric choke heater
relay can be checked by starting the engine
from cold, and placing a finger on the relay
(see illustration). It should be possible to feel
the relay switching on and off. If this is not the
case, renew the relay.
Throttle damper control solenoid
18The solenoid is on the right-hand side of
the engine compartment (see illustration). 19Disconnect the solenoid wiring plug by
pulling on the plug, not the wiring.
20Disconnect the two vacuum pipes from
the solenoid, noting their locations for use
when refitting.
21Remove the securing screw and withdraw
the solenoid from the body panel.
22Refitting is a reversal of removal, but note
that the locating lug on the solenoid bracket
should engage with the body panel, and make
sure that the vacuum pipes are correctly
connected.
Throttle damper
23Remove the air cleaner.
24Disconnect the vacuum pipe from the
throttle damper.
20ESC Hybrid system
components - removal and
refitting
5•22Engine electrical systems
20.3 Disconnecting crankshaft
speed/position sensor wiring plug - ESC
Hybrid system
20.6 Engine coolant temperature sensor
location - ESC Hybrid system
20.25 Throttle damper assembly - ESC
Hybrid system
A Securing screws
B Adjusting screwC Throttle lever20.18 Throttle damper control solenoid -
ESC Hybrid system20.17 Electric choke heater relay location
(arrowed) in main fusebox - ESC Hybrid
system
20.13 Disconnecting air charge
temperature sensor wiring plug - ESC
Hybrid system
20.5 Setting the gap between the crankshaft
speed/position sensor and the crankshaft
toothed wheel - ESC Hybrid system

25Remove the two securing screws and
detach the throttle damper and bracket
assembly from the carburettor (see
illustration).
26Commence refitting by securing the
throttle damper and bracket assembly to the
carburettor with the two screws. Ensure that
the throttle lever is correctly positioned in the
slot in the throttle damper actuating arm.
27Reconnect the vacuum pipe to the throttle
damper.
28Reconnect the air cleaner vacuum hose to
the inlet manifold, and reconnect the air
change temperature sensor wiring plug, then
place the air cleaner to one side to allow
access to the throttle damper.
29Reconnect the battery negative lead.
30Connect a tachometer to the engine in
accordance with the manufacturer’s
instructions.
31Start the engine, then check and if
necessary adjust the idle speed and mixture.
32Earth the “service adjustment” lead,
located in the battery negative wiring loom
(see illustration), for a minimum of 10
seconds. The throttle damper actuating arm
should move to the fully retracted position,
raising the engine speed.
33The engine speed should stabilise at 1700
±100 rpm. If adjustment is necessary, turn
the adjusting screw on the end of the throttle
damper actuating arm to give the correct
speed. Turn the screw clockwise to increase
the engine speed, or anti-clockwise to reduce
the engine speed.34On completion of adjustment, stop the
engine and disconnect the tachometer.
35Where necessary, ensure that any
tamperproof seals are refitted, then refit the
air cleaner, ensuring that the vacuum hose is
securely connected. Isolate the “service
adjustment” lead.
36Start the engine and check that normal
idle speed is resumed, then stop the engine.
Note:Procedures for removal and refitting of
the ignition system components and
electronic module are given elsewhere in the
relevant Sections of this Chapter.
Engine coolant temperature
sensor
2.0 litre SOHC fuel injection models
1For details of engine coolant temperature
sensor removal and refitting, refer to the
Section appertaining to the ESC II system.
1.6 and 1.8 litre (R6A type) CVH models
2The sensor is located in the side of the inlet
manifold.
3Disconnect the battery negative lead.
4Partially drain the cooling system.
5Disconnect the sensor wiring plug by
pulling on the plug, not the wiring (see
illustration).
6Unscrew the sensor from the inlet manifold
and remove it.
7Refitting is a reversal of removal. Refill the
cooling system.
2.0 litre DOHC fuel injection models
8The sensor is located in the side of the inlet
manifold, behind the throttle body. The
removal and refitting procedure is as
described for the 1.6 and 1.8 litre (R6A type)
CVH models above.
Crankshaft speed/position sensor
1.6 and 1.8 litre (R6A type) CVH
models
1.6 litre
9The sensor is located at the left-hand rear
of the cylinder block, above the starter motor
(see illustration).10Disconnect the battery negative lead.
11Remove the securing screw, and
withdraw the sensor shroud.
12Disconnect the sensor wiring plug.
13Remove the Torx securing screw, and
withdraw the sensor.
14Refitting is a reversal of removal.
1.8 litre
15Proceed as described for the ESC Hybrid
module. If a new sensor (not the original unit)
is being fitted, position it in the mounting
bracket so that it is in actual contact with one
of the teeth of the toothed wheel on the
crankshaft. Hold the sensor in this position,
and tighten the clamping screw. New sensors
have projections on their base, which will
wear away when the engine is cranking, and
automatically set the specified clearance.
2.0 litre DOHC fuel injection models
16This procedure is as described for the 2.0
litre DOHC carburettor models (ESC II
module).
Air charge temperature sensor
1.6 and 1.8 litre (R6A type) CVH
models
17The sensor is located in the side of the
CFI unit on 1.6 litre engines (see illustration),
and on the inlet manifold on 1.8 litre engines.
18Disconnect the battery negative lead.
19Disconnect the sensor wiring plug by
pulling on the plug, not the wiring.
20Unscrew the sensor from its location, and
remove it.
21Refitting is a reversal of removal, but coat
the threads of the sensor with suitable sealant
before fitting.
2.0 litre DOHC fuel injection models
22The sensor is located in the upper section
of the inlet manifold.
23Disconnect the battery negative lead.
24Disconnect the sensor wiring plug by
pulling on the plug, not the wiring (see
illustration).
25Unscrew the sensor from the inlet
manifold, and remove it.
26Refitting is a reversal of removal, noting
the torque setting for the sensor.
21EEC IV system components -
removaland refitting
Engine electrical systems 5•23
5
21.9 Crankshaft speed/position sensor
(arrowed) viewed from front of engine with
shroud removed21.17 Air charge temperature sensor
location on 1.6 litre engines (arrowed)
21.5 Disconnecting the engine coolant
temperature sensor wiring plug20.32 Service adjustment lead location
(arrowed) - ESC Hybrid system

Vehicle speed sensor
1.6 and 1.8 litre CVH (R6A type) and
2.0 litre DOHC fuel injection models
27The sensor is located in the left-hand side
of the gearbox/transmission.
28Disconnect the battery negative lead.
29Jack up the vehicle and support it
securely on axle stands (see “Jacking and
Vehicle Support”).
30Detach the sensor wiring connector from
its bracket, and separate the two halves of the
connector.
31Unscrew the securing bolt, and withdraw
the wiring connector bracket, noting its
orientation.
32Withdraw the sensor from the
gearbox/transmission casing (see
illustration).
33Before refitting the sensor, examine the
O-ring, and renew if damaged or worn.
34Refitting is a reversal of removal, ensuring
that the wiring connector bracket is correctly
located.
Manifold absolute pressure (MAP)
sensor
1.6 and 1.8 litre CVH (R6A type) and
2.0 litre DOHC fuel injection models
35The sensor is located at the rear right-
hand side of the engine compartment (see
illustration).
36Disconnect the battery negative lead.
37Remove the two screws securing the
sensor to the body panel, and carefully
withdraw the sensor, taking care not to strainthe wiring.
38Disconnect the wiring plug from the
sensor, pulling on the plug, not the wiring,
then disconnect the vacuum hose and remove
the sensor.
39Refitting is a reversal of removal.
Fuel temperature sensor -
removal and refitting
2.0 litre DOHC fuel injection models
40The sensor is located in the top of the fuel
rail.
41Disconnect the battery negative lead, and
to improve access, disconnect the wiring plug
from the air charge temperature sensor (in the
inlet manifold). Disconnect the sensor wiring
plug by pulling on the plug, not the wiring.
42Disconnect the fuel temperature sensor
wiring plug, again pulling on the plug (see
illustration).
43Unscrew the sensor from the fuel rail, and
remove it.
44Refitting is a reversal of removal, noting
the torque setting for the sensor.
Spark delay and sustain valves
1Disconnect the vacuum pipes at the valve
and withdraw the valve.
2When refitting a spark delay valve, the valve
must be positioned with the black end
(marked “CARB”) towards the carburettor and
the coloured end (marked “DIST”) towards the
distributor or electronic module (as
applicable).
3When refitting a spark sustain valve, the
valve must be positioned with the end marked
“VAC” towards the carburettor and the side
marked “DIST” towards the distributor or
electronic module (as applicable).
Ported vacuum switch
4Where fitted, the switch(es) may be located
in the inlet manifold and/or in an adapter fitted
in one of the coolant hoses.
5To remove a switch, partially drain the
cooling system. Note that there is no need to
remove the cylinder block drain plug.
6Mark the vacuum pipes for location so that
they can be refitted in their correct positions,
then disconnect the pipes from the switch.
7Unscrew the valve from its location.
8Refitting is a reversal of removal, ensuring
that the vacuum pipes are correctly
connected. Refill the cooling system.
Fuel trap
9Disconnect the vacuum pipes at the fuel
trap and withdraw the fuel trap.
10When refitting, the fuel trap must be
positioned with the black end (marked
“CARB”) towards the carburettor, and the
white side (marked “DIST”) towards the
distributor, electronic module, or ported
vacuum switch (as applicable) (see
illustration).
Spark control system additional
components
11According to model, engine and
equipment, additional components such as
one-way valves or solenoids may also be
fitted as part of the spark control system.
12The removal and refitting procedures for
these components are basically as described
previously, and provided that all attachments
are marked for position prior to removal, no
problems should be encountered.
22Spark control system
components (carburettor
models) - removal and refitting
5•24Engine electrical systems
21.24 Disconnecting the air charge
temperature sensor wiring plug21.35 Manifold absolute pressure (MAP)
sensor location
22.10 Fuel trap vacuum connection
markings21.42 Disconnecting the fuel temperature
sensor wiring plug
21.32 Withdrawing the vehicle speed
sensor from the gearbox casing