Page 71
110 APC-system
APC system
ew Bin
| |
11G 5C
VT 2.5 GR 1.0
147 146
fa hk ]
ae Se [[et228 (ll: 22A
Lm-04 Ee ge | |
E — nei
M87 M88 RD/VT 1.0
Nee eens,
152A
b+]
131
RD 1.0
D p
178 180
one [A}zs
284 ; 488] 1489 486 767 483 484
BL 0.5 GN 0.5] |BR 0.5 GR/RD 1.5 VT 0.75 SV 1.0 GN/RD 1.0
152A
ro 4 i 1
7 j 20 13 j152C
485 E
BL/RD 0.75 4 767 483 484
\ Py VT 0.75 SV 1.0 GN/RD 1.0
25 1617 4 13 20 25-10
177
12 5
481
GL/VT 1.5
CC
59 DI 205
570) 520}
fe ~ i ioe
i Ke:
481A 481A 487
GL/VT 1.5 GL/VT 1.5 SV 1.5
2 2
179 179
1 1
482 482
SV 1.5 SV 1.5
18 (i yf pa 93
Saab 900
Page 72
APC system 111
Operation
The engine is equipped with an Automatic Perform-
ance Control (APC) system, which enables the engine
to adjust itself automatically to the grade of fuel
supplied to it at any particular time.
The APC system is controlled by control unit 177,
which is supplied (+54) from fuse 10 via 29-pole
white connector 152A. The unit receives signals from
several sensors, processes the signals and then con-
trols the boost pressure of the turbocharger via sole-
noid valve 179.
The system receives information from the following
sensors:
© Knock sensor 178, which senses any knocking in
the engine
© Pressure transmitter 180 which senses the pres-
Sure in the intake pipe upstream of the throttle.
The electrical signals from the sensors and from
ignition pulse amplifier 147 (1987) or ignition sys-
tem amplifier 146 (1988) are fed continuously into
the control unit. On the basis of the electrical signals
received, the unit then controls the solenoid valve
and thus the boost pressure from the turbocharger. In
addition, it receives a signal from brake light switch
29 when the foot brake is applied, which enables the
control unit to reduce the basic boost pressure. Since
the boost pressure is continuously adjusted to the
octane rating of the fuel and the running conditions
of the engine, it has proved unnecessary to provide
the adjustment margins that must normally be al-
lowed to avoid damage to the engine. As a result,
maximum energy can be extracted from the fuel used
on any particular occasion.
Cars with the Turbo engine and Cruise Control are
equipped with vacuum switch 233, which is actuated
by vacuum pump 187 via a vacuum hose. When the
contacts open, the control unit reduces the boost
pressure to the basic value.
Fault-tracing hints
Always take the fol lowing measures before fault-trac-
ing in the APC system:
1. Disconnect the connector from the control unit.
2. Disconnect the connector from the component
which is suspected to be faulty.
3. Use an ohmmeter to check the wiring for any
open circuits, etc.
The resistance of the pressure transmitter (measured
at atmospheric pressure) is 5 - 13 ohm.
For other particulars, see the fault-tracing section in
the Service Manual, Group 2:3, Fuel system, fuel
injection.
Me Saab 900
Page 73
a
112 APC-system
Locations of components
~
22A
29
59
93
146
147
152A
152C
LO
178
179
180
233
Earthing point, radiator cross-member
Fuse holder
in the electrical distribution box, in the en-
gine compartment, on the left-hand wheel
housing
Brake light switch
at the brake pedal
2-pole connector
in the engine compartment, on the
left-hand wheel housing
Earthing point, left-hand wheel housing
member
Amplifier for the electronic ignition system
in the engine compartment, forward of 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 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.
Control unit for the APC system
in the engine compartment, forward of the
left-hand wheel housing
Knock sensor
on the engine, below the intake manifold
Solenoid valve
on the radiator fan casing
Pressure transmitter
under the facia, to the left of the steering
column (behind the knee shield)
Vacuum switch
inthe engine compartment, on the left-hand
wheel housing
Saab 900
Page 74
rer
the en-
| wheel
n the
ousing
ystem
of the
1e en-
wheel
1e en-
wheel
ssible
of the
APC system
113
Components
Page 75
114 Headlamps Se eee
| Headlamps
rae
m 28 SV 1.5 29 SV 1.5
i 152A
| 7 GR 25 [517 GR 25
| ie 30
| 20
Xx
30
IRD 2.5
SOC
GR/VT 1.5
58 58
30) 1
17. RO 1.5 GR/VT 1.5
ad 0 1 2 Sn”
BRAT 0.75 &)
} . 30A RD 0.75 (M87 10
12B GR/VT 0.5 (M88)
SE,FI,EU,GB,
ME, FE, AU
S9C
BR/VT_0.75 US, CA, JP
—_—_____
312A,
SV 0.75
==... Ook ies
SE,FTEU,CB_ME,FE,AU__US,CAJP.
1612 982
373) 373 312A
SV 0.75 SV 0.75] SV 0.75
M87 M88 ae 3 3 aes
30} 30}
316L1.5 152B
86 cS i ati 5 Be Oa Rd
exe dets “is
31
3 36.SV05 31 83413
32. RO/vT 0.5 [-
152B
fis4 32 RD/VT 0.75
CDF 215
IS
19 BL 1.5
18 GL 1.5
ae SS 23
ea Oo
a wo
oO
19A 18A =
BL10 |GL10 Pa 1_GN/RD 1.0
i s = = 12qg—4 Y
ha hs [Ihe i [l= 922A
23 GR 15 | 13, 14,
25 BL/VT 1.5 234 (US)
24 GL 15
26 VT 1.5
2B
27 8
=©
Saab 900
Page 76
11
iii |
Headlamps 115
Operation
The headlamps can only be switched on when igni-
tion switch 20 is in the parked or drive position,
Current will then flow to terminal X of light switch 10.
Full beams
When the light switch is in position 2, the supply will
be taken from terminal 56 to the “upper” coil in
lighting relay 8, via 29-pole red connector 1528. The
relay coil will be energised and the contacts will be
set to their "right-hand” position. Full beam fila-
ments 11 are supplied (+30) via the contacts of the
“lower” coil and terminal 56A, across fuses 14 and
15:
The “lower” coil is used for switching between full
beam and dipped beam. Each time the coil is ener-
gised by operation of dip switch 215, the contacts
change position and remain there until the dip switch
iS operated again.
The supply from fuse 15 is also taken to full beam
warning lamp 47G, located in the combined instru-
ment.
For particulars of the lighting wiring in light switch 10
on Cars destined for US, CA and JP, see the section
entitled "Lighting for controls, US, CA, JP”.
Headlamp flasher
The full beams can also be switched on by means of
dip switch 215, regardless of the setting of the igni-
tion switch and the light switch.
1987 model
When the dip switch is Operated, the ”lower” coil in
the lighting relay will be energised. Full beam fila-
ments 11 are then supplied (+30) from terminal 30
of the lighting relay, via the "left-hand’” contacts of
the "lower’” coil and terminal 56A.
1988 model
When the dip switch is Operated, both coils in the
lighting relay will be energised. Full beam filaments
11 are then supplied (+30) from terminal 30 of light-
ing relay 8, via the relay contacts and terminal 56A.
Dipped beams
When the light switch is in position 2, the supply will
be taken from terminal 56 to the "upper” coil in
lighting relay 8, via 29-pole red connector 152B. The
relay coil will be energised and the contacts will be
set to their ’right-hand” position. Dipped beam fila-
ments 12 are supplied (+ 30) via the contacts of the
“lower” coil and terminal 56B, across fuses 16 and
7,
Parking lights
When the headlamps are switched on, parking lights
13, which also include rear lights 14 and number
plate illumination 15, will also be alight. (On certain
markets, side marker lights 234 are also included.)
When the headlamps are switched on, the supply to
the parking lights is taken from light switch 10 in
position 2 via terminals X and 58. The parking lights
are discussed ina separate section.
GB market
Cars delivered to the GB market also have dim dipped
beams. These cars are fitted with two single-pole
connectors (60) in the electrical distribution box.
Fault-tracing hints
The headlamps will be operative when the ignition
switch is in the parked or drive position and when
light switch 10 is in position 2.
1. Check fuses 14 and 15 (full beams) and fuses
16 and 17 (dipped beams) and check that the
Supply to them is live.
2. Check the bulbs and check that the supply to
them is live. Check the earthing at each lamp.
3. Check the light Switch, the lighting relay andthe
terminals of the dip switch.
4. Check the connectors, cable harnesses and
earth connections.
For particulars of fault-tracing on the Parking lights,
see the section entitled "Parking lights”.
Page 77
116 Headlamps
Locations of components
10
an
a2
20
22A
47G
58
60
152A
152B
158
215
Earthing point in the facia
Earthing point, radiator cross-member
Lighting relay
in the electrical distribution box in the en-
gine compartment, on the left-hand wheel
housing
Light switch
on the left-hand side of the facia
Full beam filament
in the left-hand and right-hand headlamps
Dipped beam filament
in the left-hand and right-hand headlamps
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
Full beam warning lamp
in the combined instrument in the instru-
ment panel
12-pole connector
on the angle bracket, under the facia on the
left-hand side (behind the knee shield)
Single-pole connector (GB)
two in the electrical distribution box, in the
engine compartment, on the left-hand
wheel housing
29-pole white connector
29-pole red connector
in the electrical distribution box in the en-
gine compartment, on the left-hand wheel
housing.
The connectors are accessible from the inte-
rior of the car
Negative distribution terminal
in the electrical distribution box in the en-
gine compartment, on the left-hand wheel
housing
Dip switch
on the left-hand side of the steering column
Saab 900
Page 78
ne
Headlamps 117
Components
le en-
wheel
imps
imps
front
> en-
heel
stru-
the
the
and
en-
eel
\te-
2n-
3el
nn
|) €
8 10 47G 215
Saab 900
Page 79
118
Parking lights
Parking lights
148 SV.05 148 SV 05 148A SV 0.5 149 SV.05 149A SV 05 149 SV 05
tr 93 168 SV 0.5 149A SV 0.5 71 11h
— > — A, 93 7
Qa 13 2 43C BLOTS “SC GN 075 13 = B
oY (& Hh 13 13 x
i 430 BL.075 450 GNO75 4 4
2/4236, 234\X% ® z
A
43 43 45 4S
BL 0.75 BL 0.75 GN 0.75 GN 0.75
——— 17
BR/VT 075
43 BL 0.75
Pavel os 45 GN 0.75
° 12 BR/VT 0
RD 151GR/VT 15
rs) 41A 152B AMET 188) 30 2D 0.75 INET
GB feos GN/RD_10 41 GN/RO 10 | | 41 GN/RO_10 12BGR/VT OSueai
Ee] 56 xp 58
na +30
19 SEFLEU.cB
ME.FE AU
60 » [22a pe MEFEAU
: 0 588 |US.CAJP
maa 152A
3 44 GN 0.75 16 44 GN 0.75
i — a aap te cr
i 1 apes 43 BL O75 1 / | 42 BL_0.75 ts USCAJP SEFIcUcE oS
434 BL
42 BL 075 42 BL 0.75 tend 312A 5 5 |
SV 075 161 aa
pes ete ly
42 BL 075 3
373
= [ 0.75
bh GN 075
47 GN 0.75 31 3
SLA
GN 0.75
47A GN 0.75 47B GN 0.75 47C GN 0.75
15 ®,
a 189 sv 075 RiB9CSV.07S 2
A 189A SV 0.75 >
1898 <
1419 14 SV 0.75 211A SV 15 14 5 LG) 4
189D SV 10 | 189E SV 10
3-D, 5-D 7 9
42 BL 0.75 4GA GN 0.75 44 GN 0.75
1898 SV 0.75
GN 0.75 44 GN 0.75
189 SV 15
fe se ce
448 GN 0.75
OPER 189 <2
SV 10 15 is
9 S 8 8
4 14 4h 14
2-D, 4-D
Saab 900
Page 80
Pa
DS ea
Parking lights 119
Operation
The parking lights can be switched on and off by
means of light switch 10, to which the supply (+30)
is always live, regardless of the position of the igni-
tion switch.
When the light switch is to position 1 - Parking
lights” the supply to parking lights 13 is taken via
29-pole red connector 152B and fuses 18 and 19.
The left-hand side of the car is supplied across fuse
19 and the right-hand side across fuse 18.
Rear lights 14 are also supplied across fuses 18 and
19, via 29-pole white connector 152A. Number plate
illumination 15 is supplied across fuse 18.
The rear-light supplies of the 3-D and 5-D models
differ somewhat from each those of the 2-D and 4-D
models. The 3-D and 5-D models are equipped with
two additional rear lights (14) on the tailgate.
For particulars of the lighting wiring in light switch 10
on cars destined for US, CA and JP, see the section
entitled "Lighting for controls, US, CA, JP”.
Light fittings marked ”A” are for cars without inte-
grated bumpers.
U.S.A. market
Cars for the U.S.A. market are also equipped with
side marker lights 234, which are supplied via park-
ing lights 13. One-half of the bulb for each direction
indicator is used for the corresponding side marker
light.
GB market
Cars delivered to the GB market also have dim dipped
beams. These cars are also provided with a sin-
gle-pole connector 60 in the electrical distribution
box.
Fault-tracing hints
The parking lights are switched on when light switch
10 is set to position 1.
1. Check fuses 18 and 19 and check that the sup-
ply to them is live.
2. Check the bulbs and check that the supply to
them is live. Check the earthing at each lamp.
3. Check the operation of light switch 10 by mea-
suring at the light switch terminals.
4. Check the connectors, cable harnesses and
earth connections.
Saab 900