Page 61
98 __ EZK ignition system with tachometer and timing service instrument socket — 1987
Fault-tracing hints
As a general rule, the connector to the control unit
should always be disconnected when measurements
are made on the ignition system cable harness. Use
an ohmmeter, not a buzzer.
The ignition system will be energised when the igni-
tion switch is in the drive-position.
4. Check that terminal 15-of the ignition coil and
terminal 4 of the timingservice instrument
socket are live.
2. Check that terminal 4 of amplifier 146 and ter-
minal 6 of control unit 176 are live.
3. Tachometer: Check fuse 7 first and check that
the-supply to it is live. Check that terminal 3 of
the circuit board for tachometer 110 is live, and
that ignition pulses are being supplied from ig-
nition pulse amplifier 147.
4.. Ignition pulse amplifier: Check fuse 22, and
check that terminal 15 of the ignition pulse
amplifier is live, and that ignition pulses are
being supplied from the amplifier output. (Mea-
sure in the TSI socket.)
5. Check all connectors, cable harnesses and
earth connections.
See also the fault-tracing section for each compo-
nent in the Service Manual, Group 3:1, Electrical
system, Instruments.
Locations of components
The locations of the components are the same for the
1987 and 1988 models, EZK ignition system — 1988
(see pages 104—105).
Saab 900
Page 62
100
EZK ignition system with tachometer and timing service instrument socket — 1988
+30
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EZK ignition system with tachometer and timing
service instrument socket — 1988
20
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Saab 900
arn trend oe
Page 63
988
ling
EZK ignition system with tachometer and timing service instrument socket — 1988 101
Operation
The EZK ignition system is fitted only to 16-valve
engines without turbocharger. This breakerless igni-
tion system is equipped with a Hall sensor. It is
controlled by a knock sensor, which provides the
highest possible engine performance on any grade of
fuel. This provides good fuel economy and cleaner
exhaust gases.
When the ignition switch is in the start or drive posi-
tion, ignition coil 320 with integrated amplifier, and
EZK control unit 176 will be energised (E15).
Control unit 176 receives ignition pulses via a three-
core shielded cable from the Hall sensor in ignition
distributor 6. The frequency of the pulses is propor-
tional to the engine speed. The control unit then
adjusts the timing in accordance with the following
factors:
® engine speed
® engine load
@ any knocking tendencies
The pulses supplied from terminal 16 of the control
unit are amplified and adjusted in ignition coil 320
with integrated amplifier. A high-tension pulse is
generated in the secondary winding each time a
pulse breaks the primary circuit of the ignition coil.
The high-tension pulse is then supplied to the corre-
sponding spark plug (157) via distributor 6.
The ignition is set at 5° when the engine is started.
This ignition setting is dependent on the speed of the
engine, and adjustment starts at around 700 rpm. It
is adjusted in accordance with the values stored in
the control unit. (The distributor has no centrifugal or
vacuum advance mechanisms.)
Fuel system control unit 200 provides the ignition
system with information on the engine load. Throttle
angle transmitter 203 is connected (earthed) when
the throttle is closed, i.e. when the engine is idling.
When the load has exceeded the value stored in the
control unit, the timing will be retarded by around 6°
on all cylinders. The timing returns to normal in steps
of around 1° after the load has ceased to increase.
The control unit receives information on knocking in
any of the cylinders via knock sensor 178. The timing
is then retarded on the knocking cylinder only, in
steps of around 3°. This will continue until the knock-
ing ceases, or until the timing has been retarded bya
total of around 13°. The timing returns to normal in
steps of 0.35°.
EZK test connector 145 is intended for special test
equipment. Terminal 15 of the control unit delivers a
pulse for each knock detected. (Positive voltage is
supplied to the connector when the ignition switch is
in the drive position.)
Should a fault occur in the control unit, a signal
(earth) will be delivered from terminal 3, which will
cause CHECK ENGINE warning lamp 47P to flash.
(This lamp can also be activated by the fuel injection
system.)
Ignition pulses are supplied from terminal 16 of the
control unit to timing service instrument socket 73,
tachometer 110 and other systems that are depend-
ent on ignition pulses.
Tachometer
Tachometer 110, located in combined instrument
47, is supplied across fuse 7 and 29-pole red con-
nector 152B. The control pulses required for display-
ing the engine speed are supplied from EZK control
unit 176.
Timing service instrument socket
Timing service instrument (TSI) socket 73 is intended
for a special ignition service instrument and has the
following terminals:
1. Positive supply direct from battery 1
2. Earth
3. Solenoid (terminal 50) of starter motor 4
4
Positive supply from the ignition switch when
“the latter is in the start or drive position
5. Ignition pulses from EZK control unit 176
6. Notused
For a more detailed description of each component in
the ignition system, see the Service Manual, 3:1,
Electrical system, Instruments.
Saab 900
Page 64
102 EZKignition system with tachometer and timing service instrument socket — 1988 |
Fault-tracing hints
As a general rule, the connector to the control unit
should always be disconnected when measurements
are made on the ignition system cable harness. Use
an ohmmeter, not a buzzer.
The ignition system will be energised when the igni-
tion switch is in the drive position.
4. Check that fuse 3, terminal 3 on the ignition coil
and terminal 4 on the timing service instrument
socket are live.
2. Check that terminal 6 on control unit 176 is live.
3. Tachometer: Check fuse 7 first and check that
the supply to it is live. Check that terminal 3 on
the circuit board for tachometer 110 is live, and
that ignition pulses are being supplied from
control unit 176.
4. Check all connectors, cable harnesses and
earth connections.
See also the fault-tracing section for each compo-
nent in the Service Manual, Group 3:1, Electrical
system, Instruments.
Saab 900
Page 65
104
EZK ignition system with tachometer and timing service instrument socket — 1988
Locations of components
The locations of the components presented below
are the same for the EZK ignition system on 1987 and
1988 models.
4.
20
22A
47P
57
59
60
67
3
(5
93
110
145
Battery
on the right-hand side of the engine com-
partment
Earthing point in the facia
Starter motor
on the left-hand side of the engine (intake
side)
Ignition coil
on the cross-member above the radiator
Ignition distributor
at the front of the engine
Earthing point, radiator cross-member
Ignition switch
on the centre console between the front
seats
Fuse holder
in the electrical distribution box, in the en-
gine compartment, on the left-hand wheel
housing
CHECK ENGINE warning lamp
in the combined instrument on the facia
3-pole connector (116)
in the engine compartment, on the
right-hand side, at the air intake
2-pole connector
in the engine compartment, on the
right-hand side, at the air intake
Single-pole connector
in the electrical distribution box in the en-
gine compartment, on the left-hand wheel
housing
6-pole connector
one in the engine compartment, on the
right-hand side, at the air intake (two on the
1988 116 Lambda)
Timing service instrument socket
in the electrical distribution box, in the en- .
gine compartment, on the left-hand wheel
housing
Distribution block
in the engine compartment,
right-hand side
Earthing point, left-hand wheel housing
member
on the
Tachometer
in combined instrument 47 on the facia
Test tapping, EZK
inthe engine compartment, on the left-hand
wheel housing, forward of the electrical dis-
tribution box
146
147
152A
152B
157
158
159
176
178
200
201
203
204
28a:
320
Amplifier for the electronic ignition system
inthe engine compartment, on the left-hand
wheel housing
Ignition pulse amplifier
in the electrical distribution box in the en-
gine compartment, on the left-hand wheel
housing
29-pole white connector
29-pole red connector
in the engine compartment, in the electrical
distribution box on the left-hand wheel
housing. The connectors are accessible
from the interior of the car.
Spark plug
on the engine
Negative distribution terminal
in the electrical distribution box in the en-
gine compartment, on the left-hand wheel
housing
Distribution terminal +15
in the electrical distribution box, in the en-
gine compartment, on the left-hand wheel
housing
Control unit for EZK ignition system
in the engine compartment, forward of the
left-hand wheel housing
Knock sensor for the EZK system
on the engine, between the two centre in-
take ports
Control unit for the LH system
forward of the right-hand front door, below
the facia (behind the trim)
Earthing point on the engine
at the engine lifting lug
Throttle angle transmitter - LH system
on the throttle housing
Test connector - LH system
in the engine compartment, behind the
right-hand wheel housing
Earthing point on the gearbox
Ignition coil with integrated amplifier
in the engine compartment on the right-
hand side, above the battery
Saab 900
Page 66
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EZK ignition system with tachometer and timing service instrument socket— 1988 105
Components
320 (M1988)
22A 147
60 152B
73 «4158
/ 176 159 (M1987)
. 146 (M1988)
(M1987)
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147
Saab 900
SST
Page 67
106
BL 25.0
211
Battery-charging system
=
Battery-charging system
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Saab 900
Page 68
|
Operation
The charging warning lamp informs the driver of
whether or not the alternator is charging.
When the ignition switch is in the drive position, a
positive voltage will be supplied via fuse 7 and red
29-pole connector 152B to charging warning lamp
47E in the combined instrument. The other side of
the lamp is connected to alternator 2.
When the alternator is not rotating or when it is not
charging the battery for any other reason, the circuit
for the charging warning lamp will be earthed through
terminal D+ on the alternator, and the lamp will light
up.
When the alternator is charging, terminal D+ will be
at the same voltage as the supply from the fuse. The
same voltage will then be applied to both terminals of
the warning lamp, and the lamp will therefore be
extinguished.
Battery-charging system 107
Fault-tracing hints
1. Check the battery voltage at terminal B+ of the
alternator.
2. Check the fuse 7 and check that the supply to it
is live.
3. Check that the bulb in the warning lamp is in-
tact.
4. Check the connectors, cable harnesses and the
earth connections of the alternator.
5. Check that terminal D+ of the alternator is live.
6. Start the engine and measure the voltage be-
tween B+ on the alternator and earth. Also mea-
sure the voltage between D+ on the alternator
and earth. The difference between these two
voltages should not be greater than 0.7 V.
Saab 900
Page 69
a 108 __Battery-charging system |
Locations of components
1 _— Battery
on the right-hand side of the engine com-
partment
2 Alternator
on the left-hand side of the engine
4 Starter motor
on the left-hand side of the engine (intake
side)
7 Earthing point, radiator cross-member
20 Ignition switch
on the centre console between the front
seats
21 Ignition switch relay
in the electrical distribution box, in the en-
gine compartment, on the left-hand wheel
housing
22A Fuse holder
in the electrical distribution box, in the en-
gine compartment, on the left-hand wheel
housing
47E Charging warning lamp
in the combined instrument
59 2-pole connector (CAB)
one in the electrical distribution box in the
engine compartment, on the left-hand
wheel housing
{65 Distribution block
in the engine compartment, on the right-
hand side
152A 29-pole white connector
152B 29-pole red connector
152C 29-pole black connector
in the electrical distribution box in the en-
gine compartment, on the left-hand wheel
housing. The connectors are accessible
from the interior of the car.
158 Negative distribution terminal
in the electrical distribution box in the en-
gine compartment, on the left-hand wheel
housing
159 Distribution terminal +15
in the electrical distribution box, in the en-
gine compartment, on the left-hand wheel
housing
211 Earthing point on the gearbox
Saab 900
Page 70
com-
intake
front
1e en-
wheel
re en-
wheel
in the
-hand
right-
he en-
wheel
issible
he en-
wheel
he en-
wheel
B
attery-charging system
1
0
|
Components
75
Saab 900