engine FORD SIERRA 1989 2.G Engine Electrical Systems Owner's Manual

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