Page 211
a Se ee ee
ev
Speed Control system 275
Operation
Control unit 131 and selector 141 of the Speed Con-
trol system are supplied fromm fuse 8, via 29-pole
black connector 152C.
The system is switched in by means of selector 141.
When the latter is set to the ON position, the supply
will be taken to the control unit (terminal 9), and from
there to the vacuum pump and vacuum valve 187.
The pump and valve are activated when terminals 4
and 7 are earthed, These terminals are earthed in-
side the control unit, which is connected to earthing
point 3 via pedal switches 133 and 134.
When the SET SPEED button is depressed, the coil of
relay 128 will be de-energised and the relay will
close the circuit between pins 30 and 87A. Power will
be supplied to pin 6 of control unit 434 when the SET
SPEED button is depressed. Terminal 2 of the control
unit will be supplied from terminal 9, via the relay
contacts. The speed of the car will then be sensed by
speed transmitter 132. The value is supplied to ter-
minal 5 and is stored in the memory of the control
unit.
Vacuum pump 187 generates a vacuum in the vacu-
um controller. This vacuum corresponds to the se-
lected speed. The vacuum controller is connected by
chain to the accelerator linkage.
The speed of the car is continuously sensed and
compared with the value stored in the memory. Inthe
event of a deviation, the vacuum pump/vacuum valve
will increase or decrease the vacuum in the con-
troller, thus resetting the accelerator linkage.
When terminals 4 and 7 are both earthed, the vacu-
um pump will run and the valve will be closed. The
vacuum in the controller will increase, thereby in-
creasing the accelerator setting.
When terminal 4 is not earthed and termina! 7 is
earthed, the vacuum pump will be stationary and the
valve will be closed. The vacuum in the controller,
and thus the accelerator setting, will remain con-
stant.
When terminals 4 and 7 are both open (not earthed),
the vacuum pump will be stationary and the valve will
be open. The vacuum in the controller will decrease,
thereby reducing the accelerator setting.
if the clutch or brake pedal is depressed, the circuit
to earth will be opened by the corresponding pedal
switch (133 or 134). At the same time, a valve in the
pedal switches will open, so that the vacuum will be
lost. The pedal switches thus take the electrical and
vacuum systems out of operation. The system will
also be disconnected if the speed of the car drops
below 34 km/h, if the selector is set to OFF or if the
ignition is switched off.
The value inthe memory of the control unit will not be
erased, so the selected speed can be resumed after
the pedal is released, by setting the selector to the
RESUME position. Terminal 6 of the control unit will
then be supplied.
The information in the memory of the control unit is
erased when the ignition is switched off.
1988 model
Oncars with automatic transmission, selector 141 is
supplied from fuse 13, via 29-pole white connector
152A,
Turbo engine
Cars with the Turbo engine are also equipped with
vacuum switch 233. The switch is connected be-
tween control unit 177 for the APC system and to
solenoid valve 179.
When the Speed Control system is in operation, the
vacuum switch is controlled from vacuum pump 187
(via a vacuum hose), and opens the solenoid valve
circuit. This limits the boost pressure to the basic
boost pressure, thus providing smoother control of
the speed of the car.
Fault-tracing hints
4. The Speed Control system will be operative
when the ignition switch is in the drive position.
2. Check fuse 8 and check that the supply to it is
live.
3. Check that the supply to terminal 1 of control
unit 134 and to selector 1411 Is live.
4. Check the following with selector 141 set as
indicated:
ON position
Check that the supply is live ta:
— terminal 9 of the control unit
— terminal 87A of relay 128
— vacuum pump/alve 187, at the connection of
red cable 603
SET position
Check that the supply Is live to:
— terminal 2 of the control unit
— terminals 86 and 30 of relay 128
RESUME position
Check that the supply to terminal 6 of the contro!
unit is live,
5. Check the connectors, cable harnesses and
earth connections.
1988 model
On cars with automatic transmission, check fuse 13
and switch 76 for raising the idling speed, and check
that the supply to selector 144 is live.
Saab 900
Page 212
276 Speed Control system
Locations of components
3
7
22A
31
59
60
76
98
123
128
1341
132
133
134
141
152A
152C
179
187
233
Earthing point in the facia
Earthing point, radiator cross-member
Fuse holder
in the electrical distribution box, in the en-
gine compartment, on the left-hand wheel
housing
Reversing light switch
under the centre console, at the selector
lever
2-pole connector
under the facia, on the left-hand side (be-
hind the knee shield)
Single-pole connector
two under the facia on the left-hand side, at
the 29-pole connectors
Switch for raising the idling speed (auto.)
under the centre console, at the selector
lever
10-pole connector
to the left of the steering column, under the
facia
4-pole connector
under the facia, on the left-hand side (be-
hind the knee shield)
Speed Control relay
under the facia, on the left-hand side (be-
hind the knee shield)
Control unit for Speed Control
under the facia, on the left-hand side (be-
hind the knee shield)
Speed transmitter
in the combined instrument
Clutch switch for Speed Control
at the clutch pedal
Brake switch for Speed Control
at the brake pedal
Selector for Speed Control
onthe left-hand side of the steering column
29-pole white connector
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
Solenoid valve
at the front of the engine compartment,
above the radiator fan
Vacuum pump for Speed Contro!
in the engine compartment, forward of the
left-hand wheel housing
Vacuum switch for Speed Control
in the engine compartment, forward of the
left-hand wheel housing
Saah 900
Page 213
Components
98(M1988) 152C
152A (M1988)
131
128
141
179
Saab 900
Speed Control system 277
Page 214
278 Passive seat belts
Passive seat belts
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Saab 900
Page 215
ev
279
Passive seat belts
Operation
In certain cars, passive seat belts are provided for the
front-seat occupants. The seat belt consists of a
motor-driven, two-point diagonal strap and a man-
ually fastened lap strap. The diagonal strap is con-
trolled and monitored by logic box 306.
Regardless of the position of the ignition switch, the
seat-belt system is always supplied (+30) across
fuses 310 (D = driver’s side and P = passenger’s
side). G sensor 309 is designed to isolate the supply
to the logic box in the event of a collision (retardation
of more than 0.7 g).
Driver's side
The upper anchor point of the diagonal strap (the
carriage on the guide rail) is moved between the A
and B pillars by motor 308D, which is controlled by
the logic box via relays 311D and 312D. The travel of
the carriage is monitored by the two limit switches
308D:A and B. Limit switch A opens a circuit and thus
provides information to the logic box that the car-
riage has reached the A pillar, and limit switch B
opens the circuit when the carriage is locked at the B
pillar.
When the door is opened from the outside, the car-
riage is in the forward position at the A pillar. After the
door has been closed, i.e. door switch 208D is open
and ignition switch 20 is in the drive or start position,
the coil of relay 311D will be earthed via pin 23 in
logic box 306. The relay is energised and one pole of
the motor is supplied via the relay contacts, while the
other pole is earthed via relay 312D. When the car-
riage has reached the rear limit of its travel at the B
pillar, limit switch B will open. The logic box will then
open the earth circuit to the coil of relay 311D and
the motor will stop.
When the ignition is switched off or the door is
opened, the logic box will energise (via pin 22) relay
312D. The direction of rotation of the motor will then
be reversed and the carriage will move towards the A
pillar. When the carriage has reached the A pillar,
limit switch A will open and the motor will stop.
When reverse gear is engaged, reversing light switch
31 will close and a signal will be applied to the logic
box. The driver can then open the door while the
ignition is switched on, without the seat-belt car-
riage moving to the forward position.
The sensor-override solenoid in belt reel 307D over-
rides the acceleration and tipping sensors for the
diagonal strap. The solenoid is ehergised while the
carriage is travelling between the two limits of its
travel, to enable the belt to be withdrawn freely. In
addition, the solenoid is energised for 30 seconds
after the door has been opened or closed, to enable
the seat to be adjusted.
When the solenoid is energised, the circuit will be
closed at the upper contacts in the diagram (earth at
pin 21) to provide the logic box with information that
the solenoid has actually been energised. The lower
contacts sense whether or not the strap has been
wound up fully on the reel. The contacts are open
when the strap is on the reel (not connected to the
carriage).
Co-driver’s side
The diagonal strap on the co-driver’s side is driven in
the same way as that on the driver's side. (When relay
311P is energised, motor 308P moves the strap from
A to B pillar, and moves it in the opposite direction
when 312P is energised.) Reel 307P and door switch
208P have the same function as the corresponding
components on the driver's side.
When the co-driver’s door is opened from the out-
side, the seat belt may be at either the A pillar or the
Bpillar. Ifthe belt is at the B pillar, it will move to the A
pillar when the door is opened.
When the door is closed and the ignition is switched
on or if it is already switched on, the belt will move to
the B pillar, regardless of whether or not the seat is
occupied.
When the co-driver’s door is opened, the carriage
will move to the A pillar, and will remain there when
the door is closed, unless the ignition is switched on.
Warning system
Warning lamp 47S for the passive seat belts is con-
trolled by the logic box. The lamp will flash:
@ when the carriage on the driver's side is moving
from A to B pillar
@ when the carriage on the co-driver’s side moves
from the A to the B pillar and if it takes more than 8
seconds to reach the B pillar
@ if the carriage is locked at the B pillar and a fault
has occurred on the sensor-override function
@ if the carriage is not securely locked at the B pillar
Lamp 47S will light up with a steady light:
@ if the diagonal strap has worked loose from the
Carriage.
A flashing light has priority over a steady light.
The buzzer in relay 82 is actuated by the logic box
(earth at pin 20) and by the driver's side lap strap.
The buzzer will sound:
@ while the carriage for the diagonal strap is moving
from the A or B pillar when the ignition is switched
on
e for up to 8 seconds if the lap strap has not been
‘ fastened, i.e. if seat-belt switch 70 is still closed.
Seat-belt warning lamp 72 is not affected by the
passive seat-belt system. Lamp 72 will light up for
4-8 s after the ignition has been switched on.
Saab 900
Page 216
280 ~—«~Passsive seat belts
Fault-tracing hints
Check that the supply to the seat-belt system is live.
Fuse 310D protects the logic box and the seat belt on
the driver’s side, whereas fuse 310P protects the
seat belt on the co-driver’s side. (The seat belt on the
driver's side will still operate, even if fuse 310P has
blown.) Also check fuses 5, 12 and 13.
As a general rule, always disconnect the connector
from the logic box before carrying out fault-tracing on
the system. Never take any measurements with the
logic box connected or on the pins of the logic box.
The logic box is regarded as an exchange unit, and
fault-tracing should start by determining whether the
fault is in the logic box or in other components,
connectors, etc. Most of the signals to and from the
logic box can be checked using the system diagram
and the table below. The diagram shows the belt
system with the carriages at the A pillar, the car doors
open and the lap strap not fastened.
4. Ensure that the ignition is switched off and dis-
connect the connector from the logic box. Carry
out all measurements from the rear of the con-
nector.
2. Turn the ignition key to the drive position and
use a voltmeter to check that the following pins
in the connector are at battery voltage.
Pin Remarks
411 reverse gear engaged
12 ignition switch in the drive position
18 via the relay coil in 312P
19 via the relay coil in 344P
Ze via the relay coil in 312D
23 via the relay coil in 311D
25 via g sensor 309
3. Use an ohmmeter to measure between the fol-
lowing pins and earth.
Pin Resistance Remarks
1 0 ohm belt in the carriage
2 approx. 13 0hm__ bulb resistance
4 approx. 220hm ___ coil resistance
5 open circuit carriage at A pillar
6 0 ohm
(é 0 ohm co-driver’s door open
8 approx. 22 ohm ___ coil resistance
9 open circuit carriage at A pillar
10 0 ohm
13 0 ohm
14 0 ohm belt in the carriage
LZ open circuit
20 0 ohm lap strap not fastened
21 open circuit
24 0 ohm driver's door open
Saab 900
Page 217
282
Passive seat belts
Locations of components
3
20
22A
31
47S
57
58
59
60
65
70
72
76
82
98
AAS,
122
Earthing point in the facia
Ignition switch
Fuse holder
in the electrical distribution box, in the en-
gine compartment, on the left-hand wheel
housing
Reversing light switch
under the centre console, to the left of the
selector lever
Passive seat-belt warning lamp
in the combined instrument on the facia
3-pole connector
under the back seat, on the left-hand side
12-pole connector
to the left of the steering column, under the
facia, behind the knee shield
2-pole connector
one in the engine compartment, at the top
hinge of the left-hand door
one in the engine compartment, at the top
hinge of the right-hand door
Single-pole connector
two in each door, at the door switch for the
passive seat-belt system, behind the trim
two under the centre console, between the
front seats
Earthing point, back seat
Seat-belt switch - driver's side
between the driver's seat and the
co-driver’s seat
Seat-belt warning lamp
in the centre of the facia
Switch for raising the idling speed (auto.)
under the centre console, at the selector
lever
Seat belt/ignition switch warning relay
under the back seat, on the left-hand side
10-pole connector
to the left of the steering column, below the
facia, behind the knee shield
Earthing point
at the handbrake (1987)
between the ignition switch and the hand-
brake (1988)
8-pole connector
one under the driver’s seat, on the left-hand
side, under the carpet
one under the co-driver’s seat, on the
right-hand side, under the carpet
one under the back seat, on the left-hand
side
one under the back seat, on the right-hand
side
152A
152B
208D
208P
306
307D
307P
308D
308P
309
310D
310P
311D
311P
312D
312P
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.
Driver's door switch, passive seat-belt sys-
tem
at the driver's door lock, behind the trim.
Co-driver’s door switch, passive seat-belt
system
at the co-driver’s door lock, behind the trim.
Logic box for passive seat belts
under the back seat, on the left-hand side
Belt reel for passive seat belts, driver's side
on the inboard side of the driver’s seat.
Belt reel for passive seat belts, co-driver’s
side
on the inboard side of the co-driver's seat.
Motor with limit switches for passive seat
belts, driver's side
behind the driver's side B pillar, behind the
side trim.
Motor with limit switches for passive seat
belts, (co-driver’s side)
behind the co-driver’s side B pillar, behind
the side trim.
G sensor for passive seat belts
under the back seat, on the left-hand side.
Fuse (25 A) for passive seat belts, driver’s
side
Fuse (25 A) for passive seat belts, co-
driver's side
under the back seat, on the left-hand side.
Motor relay for passive seat belts, driver’s
side
Motor relay for passive seat belts, co-
driver's side
under the back seat, on the left-hand side.
Motor relay for passive seat belts, driver’s
side
Motor relay for passive seat belts, co-
driver’s side
under the back seat, on the left-hand side.
Saab 900
Page 218
Passive seat belts 283
310P 310D
Components 312P 311P 311D 312D
59 122
20 208D 65 308D:A
31 60 82
60 60 306
60 309
70
o r 58 22A
eo”
Saab 900
Page 219
284 Radio installation
Radio installation
M87 M88
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Saab 900
Page 220
ev
ev
I EE
Operation
Space has been reserved in the facia for a radio
(267). On certain markets and models, wiring has
been run for the installation of a radio, and speakers
and an electrically operated aerial have been fitted.
Two 10-pole connectors (98), one for the power sup-
ply and one for the speakers, are fitted in the radio
compartment in the facia. A coaxial cable has also
been run to the mounting point for the aerial, on the
left-hand rear wing.
Power supply
The following cables are connected to the upper
10-pole connector 98 shown on the wiring diagram:
Grey (pin 1) — Positive supply via fuse 28, which is
supplied directly from the battery (regardless of the
position of the ignition switch).
Red (pin 4) — Positive supply via the ignition switch
and fuse 20. The radio is supplied when the ignition
switch is in the parked or drive positions.
Black (pin 5) — Earth.
Green (pin 6) — For control of the electrically oper-
ated aerial (265). The motor of the electrically oper-
ated aerial is supplied via fuse 28.
Brown/white (pin 8) — Dial lighting. The supply is
taken from the instrument lighting rheostat 16/17.
Speakers
The speaker connections are made via the lower
10-pole connector shown in the diagram.
Left-hand front:
Green (pin 1) —
Brown (pin 2) +
Right-hand front:
Red (pin 3) +
Blue (pin 4) —
Left-hand rear:
Green/white (pin 5) —
Brown/white (pin 6) +
Right-hand rear:
Red/white (pin 7) +
Blue/white (pin 8) —
Each speaker is connected via single-pole connector
60.
Radio installation 285
Fault-tracing hints
1. Check the supply to the radio and the earth
connection.
Check the connectors.
Check the existing cable harness for open cir-
cuits and short circuits to earth.
Locations of components
The locations of the components are the same for the
sections entitled "Radio installation” and ”Radio in-
Stallation, 1988 (US)”. The components are listed at
the end of the section entitled "Radio installation,
1988 (US)”.
Saab 900