1991 BMW 5 SERIES ignition switch

reading should be between 400 and 500 mA.
Adjust the valve if the current reading is not as
specified. Note: The idle air stabiliser current
will fluctuate between 400 and 1100 mA if the
engine is too cold, if the coolant temperature
sensor is faulty, if there is an engine vacuum
leak, or if electrical accessories are on.
25If there is no current reading, have the idle
speed control unit (under the facia) checked
by a BMW dealer or other specialist.
26On three-wire valves, check for voltage at
the electrical connector. With the ignition on,
there should be battery voltage present at the
centre terminal (see illustration). There
should be about 10 volts between the centre
terminal and each of the outer terminals.
27If there is no voltage reading, have the idle
speed control unit (early models) or the ECU
(later models) checked by a dealer service
department or other specialist.
Adjustment (early models only)
28With the ignition switched off, connect a
tachometer in accordance with the equipment
manufacturer’s instructions.
29Make sure the ignition timing is correct
(see Chapter 5).
30Connect an ammeter to the valve as
described in paragraph 13.
31With the engine running, the current draw
should be 450 to 470 mA at 700 to 750 rpm.
32If the control current is not correct, turn
the adjusting screw until it is within the
specified range. Note: Turn the idle air bypass
screw clockwise to increase the current, or
anti-clockwise to decrease the current.
Renewal
33Remove the electrical connector and the
bracket from the idle air stabiliser valve.
Remove the valve, disconnecting the hoses.
34Refitting is the reverse of removal.
22 Exhaust system servicing-
general information
Warning: Inspect or repair
exhaust system components only
when the system is completely
cool. When working under the
vehicle, make sure it is securely
supported.
Silencer and pipes
1The exhaust system consists of the exhaust
manifold, catalytic converter, silencers, and all
connecting pipes, brackets, mountings (see
illustration)and clamps. The exhaust system
is attached to the body with brackets and
rubber mountings. If any of the parts are
improperly fitted, excessive noise and
vibration may be transmitted to the body.
2Inspect the exhaust system regularly. Look
for any damaged or bent parts, open seams,
holes, loose connections, excessive
corrosion, or other defects which could allow
exhaust fumes to enter the vehicle. Generally,
deteriorated exhaust system components
cannot be satisfactorily repaired; they should
be renewed.3If the exhaust system components are
extremely corroded or rusted together, it may
be necessary to cut off the old components
with a hacksaw. Be sure to wear safety
goggles to protect your eyes from metal
chips, and wear work gloves to protect your
hands.
4Here are some simple guidelines to follow
when repairing the exhaust system:
a) Work from the back to the front of the
vehicle when removing exhaust system
components.
b) Apply penetrating oil to the exhaust
system nuts and bolts to make them
easier to remove.
c) Use new gaskets, mountings and clamps
when fitting exhaust system components.
d) Apply anti-seize compound to the threads
of all exhaust system nuts and bolts
during reassembly.
e) Be sure to allow sufficient clearance
between newly-fitted parts and all points
on the underbody, to avoid overheating
the floorpan, and possibly damaging the
interior carpet and insulation. Pay
particularly close attention to the catalytic
converters and heat shields. Also, make
sure that the exhaust will not come into
contact with suspension parts, etc.
Catalytic converter
5Although the catalytic converter is an
emissions-related component, it is discussed
here because, physically, it’s an integral part
of the exhaust system. Always check the
converter whenever you raise the vehicle to
inspect or service the exhaust system.
6Raise and support the vehicle.
7Inspect the catalytic converter for cracks or
damage.
8Check the converter connections for
tightness.
9Check the insulation covers welded onto the
catalytic converter for damage or a loose fit.
Caution: If an insulation cover is
dented so that it touches the
converter housing inside,
excessive heat may be
transferred to the floor.
10Start the engine and run it at idle speed.
Check all converter connections for exhaust
gas leakage.
4•20 Fuel and exhaust systems
22.1 A typical exhaust system rubber
mounting21.26 Check for battery voltage on the
centre terminal

Fuel injection system - fault finding
L-Jetronic fuel injection system
Engine difficult to start, or fails to start (when cold)
Probable cause Corrective action
Cold start injector or thermotime switch faulty Test cold start injector and thermotime switch. Renew faulty components (see Section 19)
Fuel pump inoperative Check fuel pump fuse and fuel pump relay (see Sections 3 and 4)
Airflow meter flap (door) binding or stuck
in open position Inspect the airflow meter for damage (see Section 16)
Fuel pressure incorrect Test system pressure (see Section 3). Test fuel pressure regulator (Section 18)
Intake air leaks Inspect all vacuum lines, air ducts, and oil filler and dipstick seals
Fuel injectors clogged or not operating Check fuel injectors (see Section 20) and wiring harness
Coolant temperature sensor faulty or
wiring problem Test coolant temperature sensor (see Chapter 6, Section 4)
Throttle position sensor (TPS) incorrectly adjusted Check TPS adjustment (see Chapter 6, Section 4)
Incorrect ignition timing Check ignition timing (see Chapter 5). Check vacuum advance system
Dirt or other contaminants in fuel Check the fuel and drain the tank if necessary
Faulty ECU Have the ECU tested at a dealer service department or other specialist
Engine difficult to start, or fails to start (when warm)
Probable cause Corrective action
Cold start injector leaking or operating continuously Test cold start injector and thermotime switch (see Section 19)
Fuel pressure incorrect Test fuel pump(s). Renew if necessary (see Section 3)
Insufficient residual fuel pressure Test residual fuel pressure. Renew fuel pump or fuel accumulator as necessary
(see Section 18)
Fuel leak(s) Inspect fuel lines and fuel injectors for leaks. Correct leaks as required (see Chapter 4)
Coolant temperature sensor faulty or
wiring problem Test coolant temperature sensor (see Chapter 6, Section 4)
Vapour lock (warm weather) Check fuel pressure (see Section 3)
EVAP system faulty (where applicable) Check EVAP system (see Chapter 6, Section 6)
Incorrect ignition timing Check ignition timing (see Chapter 5). Check vacuum advance system
Faulty ECU Have the ECU tested at a dealer service department or other specialist
Idle speed control system faulty Test the idle air stabiliser valve (see Section 21)
Engine misses and hesitates under load
Probable cause Corrective action
Fuel injector clogged or faulty Test fuel injectors. Check for clogged injector lines. Renew faulty injectors (see Section 20)
Fuel pressure incorrect Test fuel system pressure (see Section 3). Test fuel pressure regulator (see Section 18)
Fuel leak(s) Inspect fuel lines and fuel injectors for leaks (see Chapter 4)
Engine maintenance Tune-up engine (see Chapter 1). Check the distributor cap, rotor, HT leads and spark
plugs, and renew any faulty components
Airflow meter flap (door) binding, or
stuck in open position Inspect the airflow meter for damage (see Section 16)
Intake air leaks Inspect all vacuum lines, air ducts and oil filler and dipstick seals
Engine has erratic idle speed
Probable cause Corrective action
Idle air stabiliser valve faulty Check the idle air stabiliser valve (see Section 21)
No power to the idle air stabiliser valve Check the idle air stabiliser relay and wiring circuit (see Chapter 12)
Vacuum advance system faulty Check vacuum advance system and electronic vacuum advance relay
Idle speed control unit faulty Have the idle speed control unit checked by a dealer
Motronic fuel injection system
Note:With this system, when faults occur, the ECU stores a fault code in its memory. These codes can only be read by a BMW dealer, as
specialised equipment is required. It may save time to have at least the initial fault diagnosis carried out by a dealer.
Lack of power
Probable cause Corrective action
Coolant temperature sensor faulty, Test coolant temperature sensor and wiring. Repair wiring or renew sensor if
or wire to sensor broken faulty (see Chapter 6)
Fuel pressure incorrect Check fuel pressure from main pump and transfer pump, as applicable (see Section 3)
Throttle plate not opening fully Check accelerator cable adjustment to make sure throttle is opening fully. Adjust cable if
necessary (see Section 9)
Fuel and exhaust systems 4•21
4

1 General information
The engine electrical systems include all
ignition, charging and starting components.
Because of their engine-related functions,
these components are discussed separately
from body-related electrical devices such as
the lights, the instruments, etc. (which are
included in Chapter 12).
Always observe the following precautions
when working on the electrical systems:
a) Be extremely careful when servicing
engine electrical components. They are
easily damaged if improperly checked,
connected or handled.
b) Never leave the ignition switched on for
long periods of time with the engine off.
c) Don’t disconnect the battery cables while
the engine is running.
d) Observe the rules when jump-starting
your vehicle. Read the precautions at the
front of this manual.
e) Always disconnect the battery negative
cable first, and connect it last, to reduce
the risk of accidental short-circuits.
f) Don’t charge the battery with the cables
connected to the terminals.
It’s also a good idea to review the safety-
related information regarding the engine
electrical systems in the “Safety first”section
near the front of this manual before beginning
any operation included in this Chapter.
Caution: If the radio in your
vehicle is equipped with an anti-
theft system, make sure you
have the correct activation code
before disconnecting the battery. Refer to
the information on page 0-7 at the front of
this manual before detaching the cable.
Note: If, after connecting the battery, the
wrong language appears on the instrument
panel display, refer to page 0-7 for the
language resetting procedure.
2 Battery-
emergency jump starting
1
Refer to the “Jump starting”procedure at
the front of this manual.
3 Battery- removal and refitting
1
Note:Depending on the model, the battery
may be located in the engine compartment, in
the rear luggage compartment, or under the
rear seat. Consult your owners handbook for
the location of the battery, if not already
known to you.Caution: If the radio in your
vehicle is equipped with an anti-
theft system, make sure you
have the correct activation code
before disconnecting the battery. Refer to
the information on page 0-7 at the front of
this manual before detaching the cable.
Note: If, after connecting the battery, the
wrong language appears on the instrument
panel display, refer to page 0-7 for the
language resetting procedure.
1Disconnect the battery negative cable.
2Detach the cable from the positive terminal.
3Remove the battery hold-down bracket
(see illustrations)and lift out the battery. Be
careful - it’s heavy. Do not tilt the battery to
any extent while it is being removed, and
store it upright.
4While the battery is out, inspect the carrier
(tray) for corrosion (see Chapter 1).
5If you are renewing the battery, make sure
that you get one that’s identical, with the
same dimensions, amperage rating, cold
cranking rating, etc.
6Refitting is the reverse of removal.
4 Battery cables-
check and renewal
1
Check
1Periodically inspect the entire length of
each battery cable for damage, cracked or
burned insulation, and corrosion.
Poor battery cable connections can cause
starting problems and decreased engine
performance.
Caution: If the radio in your
vehicle is equipped with an anti-
theft system, make sure you
have the correct activation code
before disconnecting the battery. Refer to
the information on page 0-7 at the front of
this manual before detaching the cable.
Note: If, after connecting the battery, the
wrong language appears on the instrument
panel display, refer to page 0-7 for the
language resetting procedure.2Check the cable-to-terminal connections at
the ends of the cables for cracks, loose wire
strands, and corrosion. The presence of
white, fluffy deposits under the insulation at
the cable terminal connection is a sign that
the cable is corroded, and should be cleaned
or renewed. Check the terminals for
distortion, missing mounting bolts, and
corrosion.
Renewal
3When removing the cables, always
disconnect the negative cable first and
connect it up last. This reduces the risk of
accidental short-circuits. Even if only a new
positive cable is being fitted, be sure to
disconnect the negative cable from the
battery first (see Chapter 1 for further
information regarding battery cable removal).
4Disconnect the old cables from the battery,
then trace each of them to their opposite ends
and detach them from the starter solenoid
and earth terminals. Note the routing of each
cable to ensure correct refitting.
5If the old cables are to be renewed, take
them with you when buying new cables. It is
vitally important that you renew the cables
with identical parts. Cables have character-
istics that make them easy to identify: positive
cables are usually red, larger in cross-section,
and have a larger-diameter battery post
clamp; earth cables are usually black, smaller
in cross-section, and have a slightly smaller
diameter clamp for the negative post.
6Clean the threads of the solenoid or earth
connection with a wire brush to remove rust
and corrosion.
7Attach the cable to the solenoid or earth
connection, and tighten the mounting nut/bolt
securely.
8Before connecting a new cable to the
battery, make sure that it reaches the battery
post without having to be stretched.
9Connect the positive cable first, followed by
the negative cable.
5•2 Engine electrical systems
3.3b The battery is mounted under the
rear seat on some models
3.3a Always detach the cable from the
battery negative terminal first, then detach
the positive cable – to remove the hold-
down assembly, remove the nuts (arrowed)
or single bolt
Apply a light coat of battery
terminal corrosion inhibitor,
or petroleum jelly, to the
terminal threads, to prevent
future corrosion.

5 Ignition system- general
information and precautions
The ignition system includes the ignition
switch, the battery, the distributor, the primary
(low-voltage/low-tension or LT) and
secondary (high-voltage/high-tension or HT)
wiring circuits, the spark plugs and the spark
plug leads. Models fitted with a carburettor or
L-Jetronic fuel injection are equipped with a
Transistorised Coil Ignition (TCI) system.
Models fitted with the Motronic fuel injection
system have the ignition system incorporated
within the Motronic system (Digital Motor
Electronics or DME).
Transistorised Coil Ignition (TCI)
system
This system is has four major components;
the impulse generator, the ignition control
unit, the coil, and the spark plugs. The
impulse generator provides a timing signal for
the ignition system. Equivalent to cam-
actuated breaker points in a standard
distributor, the impulse generator creates an
A/C voltage signal every time the trigger
wheel tabs pass the impulse generator tabs.
When the ignition control unit (capacitive
discharge unit) receives the voltage signal, it
triggers a spark discharge from the coil by
interrupting the primary coil circuit. The
ignition dwell (coil charging time) is adjusted
by the ignition control unit for the most
intense spark. Note: The air gap (distance
between the impulse generator and trigger
wheel tabs) can be adjusted (see Section 11).
Ignition timing is mechanically adjusted
(see Section 7). A centrifugal advance unit
that consists of spring-loaded rotating
weights advances ignition timing as engine
speed increases. The vacuum advance
adjusts ignition timing to compensate for
changes in engine load.
Motronic ignition system
This system, also known as Digital Motor
Electronics (DME), incorporates all ignition
and fuel injection functions into one central
control unit or ECU (computer). The ignition
timing is based on inputs the ECU receives for
engine load, engine speed, coolant
temperature and intake air temperature. The
only function the distributor performs is the
distribution of the high voltage signal to the
individual spark plugs. The distributor is
attached directly to the cylinder head. There is
no mechanical spark advance system used on
these systems.
Ignition timing is electronically-controlled,
and is not adjustable on Motronic systems.
During starting, a crankshaft position sensor
(reference sensor) relays the crankshaft
position to the ECU, and an initial baseline
ignition point is determined. Once the engineis running, the ignition timing is continually
changing, based on the various input signals
to the ECU. Engine speed is signalled by a
speed sensor. Early Motronic systems have
the position reference sensor and the speed
sensor mounted on the bellhousing over the
flywheel on the left-hand side. Later Motronic
systems have a single sensor (pulse sensor)
mounted over the crankshaft pulley. This
sensor functions as a speed sensor as well as
a position reference sensor. Refer to Sec-
tion 12 for checking and renewing the ignition
sensors. Note: Some models are equipped
with a TDC sensor mounted on the front of the
engine. This sensor is strictly for the BMW
service test unit, and it is not part of the
Motronic ignition system.
Precautions
Certain precautions must be observed
when working on a transistorised ignition
system.
a) Do not disconnect the battery cables
when the engine is running
b) Make sure the ignition control unit (TCI
ignition system) is always well earthed
(see Section 10).
c) Keep water away from the distributor and
HT leads.
d) If a tachometer is to be connected to the
engine, always connect the tachometer
positive (+) lead to the ignition coil
negative terminal (-) and never to the
distributor.
e) Do not allow the coil terminals to be
earthed, as the impulse generator or coil
could be damaged.
f) Do not leave the ignition switch on for
more than ten minutes with the engine
off, or if the engine will not start.
6 Ignition system- check
2
Warning: Because of the high
voltage generated by the ignition
system, extreme care should be
taken whenever an operation is
performed involving ignition components.
This not only includes the impulse
generator (electronic ignition), coil,
distributor and spark plug HT leads, but
related components such as spark plug
connectors, tachometer and other test
equipment.
1If the engine turns over but will not start,
disconnect the spark plug HT lead from any
spark plug, and attach it to a calibrated spark
tester (available at most car accessory
shops).
Note:There are two different types of spark
testers. Be sure to specify electronic
(breakerless) ignition. Connect the clip on thetester to an earth point such as a metal
bracket (see illustration).
2If you are unable to obtain a calibrated
spark tester, remove the spark plug HT lead
from one of the spark plugs. Using an
insulated tool, hold the lead about a quarter-
inch from the engine block - make sure the
gap is not more than a quarter-inch, or
damage may be caused to the electronic
components.
3Crank the engine, and observe the tip of the
tester or spark plug HT lead to see if a spark
occurs. If bright-blue, well-defined sparks
occur, sufficient voltage is reaching the plugs
to fire the engine. However, the plugs
themselves may be fouled, so remove and
check them as described in Chapter 1.
4If there’s no spark, check another HT lead
in the same manner. A few sparks followed by
no spark is the same condition as no spark at
all.
5If no spark occurs, remove the distributor
cap, and check the cap and rotor as
described in Chapter 1. If moisture is present,
use a water-dispersant aerosol (or something
similar) to dry out the cap and rotor, then refit
the cap and repeat the spark test.
6If there’s still no spark, disconnect the coil
HT lead from the distributor cap, and
test this lead as described for the spark plug
leads.
7If no spark occurs, check the primary wire
connections at the coil to make sure they’re
clean and tight. Make any necessary repairs,
then repeat the check.
8If sparks do occur from the coil HT lead, the
distributor cap, rotor, plug HT lead(s) or spark
plug(s) may be defective. If there’s still no
spark, the coil-to-cap HT lead may be
defective. If a substitute lead doesn’t make
any difference, check the ignition coil (see
Section 9). Note:Refer to Sections 10 and 11
for more test procedures on the distributors
fitted with the TCI ignition system.
Engine electrical systems 5•3
6.1 To use a spark tester, simply
disconnect a spark plug HT lead, clip the
tester to a convenient earth (like a valve
cover bolt or nut) and operate the starter –
if there is enough power to fire the plug,
sparks will be visible between the
electrode tip and the tester body
5

7 Ignition timing (TCI system)-
check and adjustment
4
Warning: Keep hands, equipment
and wires well clear of the
viscous cooling fan during
adjustment of the ignition timing.
Note:This Section describes the procedure
for checking and adjusting the ignition timing
on engines fitted with the TCI system. On
engines fitted with the Motronic engine
management system, the ignition timing is
controlled by the electronic control unit, and
no adjustment is possible. The timing can be
checked using the following procedure, but no
ignition timing values were available at the
time of writing. If the timing is thought to be
incorrect, refer to a BMW dealer.
1Some special tools are required for this
procedure (see illustration). The engine must
be at normal operating temperature, and the
air conditioning (where fitted) must be
switched off. Make sure the idle speed is
correct.
2Apply the handbrake, and chock the wheels
to prevent movement of the vehicle. The
transmission must be in neutral (manual) or
Park (automatic).
3The timing marks are located on the engine
flywheel (viewed through the timing checkhole in the bellhousing) and/or on the vibration
damper on the front of the engine.
4Where applicable, disconnect the vacuum
hose from the distributor vacuum advance
unit.
5Connect a tachometer and timing light
according to the equipment manufacturer’s
instructions (an inductive pick-up timing light
is preferred). Generally, the power leads for
the timing light are attached to the battery
terminals, and the pick-up lead is attached to
the No 1 spark plug HT lead. The No 1 spark
plug is the one at the front of the engine.
Caution: If an inductive pick-up
timing light isn’t available, don’t
puncture the spark plug HT lead
to attach the timing light pick-up
lead. Instead, use an adapter between the
spark plug and HT lead. If the insulation on
the HT lead is damaged, the secondary
voltage will jump to earth at the damaged
point, and the engine will misfire.
Note:On some models, a TDC transmitter is
fitted for checking the ignition system.
However, a special BMW tester must be
connected to the diagnostic socket to use it,
so unless the special tester is available, a
conventional timing light should be used. The
ignition timing mark may be on the vibration
damper, but if not, normally the TDC mark will
be. If the timing light is of the adjustable delay
type, then the ignition timing may be
determined by zeroing the adjustment, then
turning the adjustment until the TDC marks are
aligned, and then reading off the amount of
advance from the timing light. If a standard
timing light is being used, make a mark on the
vibration damper in accordance with the
specified advance, using the following formula
to calculate the distance from the TDC mark
to the timing mark:
Distance = 2Pr x advance
360
where P = 3.142
r = radius of vibration damper
advance = specified advance
BTDC in degrees
6With the ignition off, loosen the distributor
clamp nut just enough to allow the distributor
to pivot without any slipping.7Make sure the timing light wires are routed
away from the drivebelts and fan, then start
the engine.
8Raise the engine rpm to the specified
speed, and then point the flashing timing light
at the timing marks - be very careful of moving
engine components.
9The mark on the flywheel or vibration
damper will appear stationary. If it’s aligned
with the specified point on the bellhousing or
engine front cover, the ignition timing is
correct (see illustrations).
10If the marks aren’t aligned, adjustment is
required. Turn the distributor very slowly until
the marks are aligned, taking care not to
touch the HT leads.
11Tighten the nut on the distributor clamp,
and recheck the timing.
12Switch off the engine, and remove the
timing light and tachometer. Reconnect the
vacuum hose where applicable.
8 Distributor-
removal and refitting
4
TCI system
Removal
1After carefully marking them for position,
remove the coil HT lead and spark plug HT
leads from the distributor cap (see Chapter 1).
2Remove No 1 spark plug (the one nearest
you when you are standing in front of the
engine).
3Manually rotate the engine to Top Dead
Centre (TDC) on the compression stroke for
No 1 piston (see Chapter 2A)
4Carefully mark the vacuum hoses, if more
than one is present on your distributor.
5Disconnect the vacuum hose(s).
6Disconnect the primary circuit wires from
the distributor.
7Mark the relationship of the rotor tip to the
distributor housing (see illustration). Also
mark the relationship of the distributor
housing to the engine.
5•4 Engine electrical systems
7.1 Tools for checking and adjusting the
ignition timing
1Vacuum plugs- Vacuum hoses will, in
most cases, have to be disconnected and
plugged. Moulded plugs in various shapes
and sizes can be used for this, if wished
2Inductive pick-up timing light- Flashes a
bright, concentrated beam of light when
No 1 spark plug fires. Connect the leads
according to the instructions supplied with
the light
3Distributor spanner - On some models,
the hold-down bolt for the distributor is
difficult to reach and turn with conventional
spanners or sockets. A special spanner like
this must be used
7.9a Flywheel “OT” timing mark 7.9b Flywheel “OZ” timing mark

8Use a digital voltmeter for the following
tests:
a) On Bosch systems, connect the positive
probe to connector terminal 5, and the
negative probe to terminal 6 (see
illustration).
b) On Siemens/Telefunken systems, connect
the positive probe to terminal (+) of the
smaller connector, and the negative
probe to terminal (-).
9Have an assistant crank the engine over,
and check that there is 1 to 2 volts A/C
present. If there is no voltage, check the
wiring harness between the impulse generator
(in the distributor) and the control unit. If the
harness is OK, check the impulse generator
resistance.
Warning: Do not crank the
engine over for an excessive
length of time. If necessary,
disconnect the cold start injector
electrical connector (see Chapter 4) to
stop the flow of fuel into the engine.
10To check the resistance in the impulse
generator, proceed as described for your
system below:
a) On Bosch units, measure the resistance
between connector terminals 5 and 6
(see illustration 10.8). The reading
should be 1000 to 1200 ohms.
b) On Siemens/Telefunken units, measure
the resistance between the terminals of
the smaller connector. The reading should
be 1000 to 1200 ohms.
11If the resistance readings are incorrect,
renew the impulse generator. If the resistance
readings for the impulse generator are correct
and the control unit voltages (supply voltage
[paragraphs 1 to 6] and signal voltage
[paragraphs 7 to 9]) are incorrect, renew the
control unit.
Renewal
Ignition control unit
12Make sure the ignition is switched off.
13Disconnect the electrical connector(s)
from the control unit.
14Remove the mounting screws from the
control unit, and lift it from the engine
compartment.15Refitting is the reverse of removal. Note:
On Bosch control units, a special dielectric
grease is used between the heat sink and the
back of the control unit. In the event the two
are separated (renewal or testing) the old
grease must be removed, and the heat sink
cleaned off using 180-grit sandpaper. Apply
Curil K2 (Bosch part number 81 22 9 243). A
silicon dielectric compound can be used as a
substitute. This treatment is very important for
the long life of these expensive ignition parts.
Impulse generator
Caution: If the radio in your
vehicle is equipped with an anti-
theft system, make sure you
have the correct activation code
before disconnecting the battery. Refer to
the information on page 0-7 at the front of
this manual before detaching the cable.
Note: If, after connecting the battery, the
wrong language appears on the instrument
panel display, refer to page 0-7 for the
language resetting procedure.
16Disconnect the battery negative cable.
17Remove the distributor from the engine
(see Section 8).
18Using a pair of circlip pliers, remove the
circlip retaining the trigger wheel (see
illustration).
19Use two flat-bladed screwdrivers
positioned at opposite sides of the trigger
wheel, and carefully prise it up (see
illustration). Note: Push the screwdrivers in
as far as possible without bending the trigger
wheel. Prise only on the strongest, centre
portion of the trigger wheel. In the event the
trigger wheel is bent, it must be replaced with
a new one. Note:Be sure not to lose the roll
pin when lifting out the trigger wheel.
20Remove the mounting screws from the
impulse generator electrical connector, the
vacuum diaphragm and the baseplate.
21Remove the two screws from the vacuum
advance unit, and separate it from the
distributor by moving the assembly down
while unhooking it from the baseplate pin.
22Use circlip pliers to remove the circlip that
retains the impulse generator and the
baseplate assembly.
23Carefully remove the impulse generator
and the baseplate assembly as a single unit.24Remove the three screws, and separate
the baseplate assembly from the impulse
generator.
25Refitting is the reverse of removal. Note:
Be sure to position the insulating ring between
the generator coil and the baseplate. It must
be centred before tightening the mounting
screws. Also, it will be necessary to
check/adjust the air gap if the trigger wheel
has been removed, or tampered with to the
point that the clearance is incorrect (see
Section 11).
11 Air gap (TCI system)-
check and adjustment
2
Caution: If the radio in your
vehicle is equipped with an anti-
theft system, make sure you
have the correct activation code
before disconnecting the battery. Refer to
the information on page 0-7 at the front of
this manual before detaching the cable.
Note: If, after connecting the battery, the
wrong language appears on the instrument
panel display, refer to page 0-7 for the
language resetting procedure.
1Disconnect the battery negative cable.
2Insert a brass feeler gauge between the
trigger wheel tab and the impulse generator
(see illustration). Slide the feeler gauge up
Engine electrical systems 5•7
10.19 Carefully prise the trigger wheel off
the distributor shaft10.18 Use circlip pliers and remove the
circlip from the distributor shaft10.8 Back-probe the ignition control unit
connector, and check for signal voltage on
terminals 5 and 6 (Bosch system shown). It
is very helpful to use angled probes
11.2 Use a brass feeler gauge to check
the air gap (be sure the gauge rubs lightly
against the trigger wheel as well as the
locating pin for the correct adjustment)
5

Refer to the information on page 0-7 at the
front of this manual before detaching the
cable.
Note: If, after connecting the battery, the
wrong language appears on the instrument
panel display, refer to page 0-7 for the
language resetting procedure.
1Disconnect the battery negative cable.
Bosch alternator
2Remove the voltage regulator from the back
of the alternator (see Section 16).
3Measure the length of the brushes (see
illustration). They should not be less than
6.0 mm. If any are worn past this point, renew
them all as a set. 4Also check for excessively worn slip rings
(see illustration 16.5).
5The brushes are retained either by set
screws or by solder. If you are not skilled at
soldering, it may be best to have an auto
electrician fit the new brushes. Note: Be
careful not to apply heat to the solder joint for
more than 5 seconds. If necessary, use a heat
sink to capture the excess heat. This can be
accomplished by clamping a pair of needle-
nose pliers next to the solder joint.
6On the screw type, hold the assembly in
place and refit the screws. Tighten them
evenly, a little at a time, so the holder isn’t
distorted.
7Refit the regulator assembly to the
alternator.8Reconnect the battery negative cable.
Motorola alternator
9Remove the alternator.
10The brushes are mounted under the
regulator on the rear of the alternator (see
illustration 16.7).
11Remove the mounting screws and
insulating washers, and separate the voltage
regulator and brush holder from the brush end
housing.
12Measure the length of the brushes (see
illustration 17.3). If any brush is less then
6.0 mm long, renew them all as a set.
13Make sure the brushes move smoothly in
the holder.
14Refit the brush holder/regulator. Tighten
the screws securely. Make sure the brushes
aren’t earthed.
15Refitting is the reverse of removal.
18 Starting system- general
information and precautions
The sole function of the starting system is
to turn over the engine quickly enough to
allow it to start.
The starting system consists of the battery,
the starter motor, the starter solenoid, the
ignition switch, and the wires connecting
them. The solenoid is mounted directly on the
starter motor. The starter/solenoid motor
assembly is fitted on the lower part of the
engine, next to the transmission bellhousing.
When the ignition key is turned to the Start
position, the starter solenoid is actuated
through the starter control circuit. The starter
solenoid then connects the battery to the
starter, and moves the starter pinion into
mesh with the flywheel ring gear. The battery
supplies the electrical energy to the starter
motor, which does the actual work of cranking
the engine.
The starter motor on some manual
transmission vehicles can only be operated
when the clutch pedal is depressed. On a
vehicle equipped with automatic
transmission, the starter can only be operated
Engine electrical systems 5•11
17.3 Check the brush length in the normal
rest position (spring uncoiled)
5
16.7 Exploded view of the Motorola alternator

when the transmission selector lever is in Park
or Neutral.
Always detach the battery negative cable
before working on the starting system.
19 Starter motor-
in-vehicle check
2
Note:Before diagnosing starter problems,
make sure the battery is fully charged.
1If the starter motor does not turn at all when
the switch is operated, make sure that the
gear lever is in Neutral or Park (automatic
transmission) or, where applicable, that the
clutch pedal is depressed (manual
transmission).
2Make sure that the battery is charged, and
that all cables, both at the battery and starter
solenoid terminals, are clean and secure.
3If the starter motor spins but the engine is
not cranking, the overrun clutch in the starter
motor is slipping, and the starter motor must
be renewed.
4If, when the switch is actuated, the starter
motor does not operate at all but the solenoid
clicks, then the problem lies either in the
battery, the main solenoid contacts, or the
starter motor itself (or the engine is seized).
5If the solenoid plunger cannot be heard
when the switch is actuated, the battery is
faulty, the switch is defective, the fusible link
is burned-out (the circuit is open), or the
solenoid itself is defective.
6To check the solenoid, connect a jumper
lead between the battery (+) and the ignition
switch wire terminal (the small terminal) on the
solenoid. If the starter motor now operates,
the solenoid is OK and the problem is in the
ignition switch, starter inhibitor switch
(automatic transmission models), clutch
switch (some manual transmission models), or
the wiring.
7If the starter motor still does not operate,
remove the starter/solenoid assembly for
dismantling, testing and repair.
8If the starter motor cranks the engine at an
abnormally-slow speed, first make sure that
the battery is charged, and that all terminal
connections are tight. If the engine is partially-
seized, or has the wrong viscosity oil in it, it
will crank slowly.
9Run the engine until normal operating
temperature is reached, then disconnect the
coil HT lead from the distributor cap and earth
it on the engine.
10Connect a voltmeter positive lead to the
battery positive post, and connect the
negative lead to the negative post.11Crank the engine, and take the voltmeter
readings as soon as a steady figure is
indicated. Do not allow the starter motor to
turn for more than 10 seconds at a time. A
reading of 9 volts or more, with the starter
motor turning at normal cranking speed, is
normal. If the reading is 9 volts or more but
the cranking speed is slow, the solenoid
contacts are burned, there is a bad
connection, or the starter motor itself is faulty.
If the reading is less than 9 volts and the
cranking speed is slow, the starter motor is
faulty or the battery is responsible (defective
or discharged).
20 Starter motor-
removal and refitting
1
Note:If the starter motor is defective, it should
be renewed, or taken to an auto electrical
specialist for repair. Overhaul of the starter
motor is unlikely to be a practical proposition
for the home mechanic, even if spare parts are
available. However, the solenoid can be
renewed separately (see Section 21).
Removal
Caution: If the radio in your
vehicle is equipped with an anti-
theft system, make sure you
have the correct activation code
before disconnecting the battery. Refer to
the information on page 0-7 at the front of
this manual before detaching the cable.
Note: If, after connecting the battery, the
wrong language appears on the instrument
panel display, refer to page 0-7 for the
language resetting procedure.
1Detach the battery negative cable.
2Raise the vehicle and support it securely on
axle stands.
3Clearly label the wires from the terminals onthe starter motor and solenoid, then
disconnect them. Note: On some models, it
may be necessary to remove the air cleaner
(see Chapter 4), coolant expansion tank (see
Chapter 3) and the heater hoses to gain
access to the top of the starter. Carefully label
any hoses or components that need to be
removed from the engine compartment, to
avoid confusion when reassembling.
4Unscrew the mounting bolts and detach the
starter (see illustrations).
Refitting
5Refitting is the reverse of removal.
21 Starter solenoid-
removal and refitting
1
Removal
Caution: If the radio in your
vehicle is equipped with an anti-
theft system, make sure you
have the correct activation code
before disconnecting the battery. Refer to
the information on page 0-7 at the front of
this manual before detaching the cable.
Note: If, after connecting the battery, the
wrong language appears on the instrument
panel display, refer to page 0-7 for the
language resetting procedure.
1Disconnect the battery negative cable.
2Remove the starter motor (see Section 20).
3Disconnect the cable from the solenoid to
the starter motor terminal.
4Remove the screws which secure the
solenoid to the starter motor.
5Detach the solenoid from the starter body.
6Remove the plunger and plunger spring.
Refitting
7Refitting is the reverse of removal.
5•12 Engine electrical systems
20.4b Withdrawing the starter motor from
the M40 engine20.4a Working under the vehicle, remove
the starter lower mounting bolt and nut
(arrowed)