Description Of Operation - Saab 9000 1995 Service Manual

Description of operation
Starting system
Current (+30 circuit) is supplied from battery 1 to ig-
nition switch 20 and also direct to connection 30 on
starter motor 4.
When the ignition switch is turned to the Start posi-
tion, current (+50 circuit) is supplied to the actuating
coil of the solenoid. The actuating coil closes the
start contact, allowing current from the battery to
flow through the starter motor which then starts to
rotate
In certain markets, current (+50 circuit) is supplied
to the anti-theft alarm control module (289) and
starter interlock relay 452.
Automatic transmission
On cars with automatic transmission, starter motor
interlock 77 is fitted to prevent the engine from be-
ing started when the selector lever is in position 1 ,
2, 3, Dor R.
Charging system
The charging warning lamp informs the driver
whether the generator is charging the battery or not.
When ignition switch 20 is in the Drive position, pos-
itive voltage ( + 15 circuit) is supplied via fuse 13 to
charging warning lamp 47E in the main instrument
display panel and then on to generator 2.
When the generator is not rotating or if it is not
charging for some reason or other, the charging
warning_ lamp circuit is grounded through the gen-
erator and the lamp will light up.
When the generator is charging, connection D+ re-
ceives the same voltage as B+. The charging lamp
is then supplied with the same voltage on both con-
nections and the lamp goes out.
Important:
Since the field excitation of the generator is built up
through the incandescent bulb, the bulb rating (2W)
must not be changed.
To increase the field excitation still further, a resistor
is connected in parallel with the bulb.
A diode is connected in series with the charging
lamp to prevent reverse currents.
Starting and charging systems 51
Fault diagnosis hints
Starting system
1 Check the battery positive voltage on starter mo-
tor 4, connection 30.
2 Check the operating voltage on the starter mo-
tor solenoid with the ignition switch in the Start
position.
3 Check the terminal blocks and wiring harness.
4 Check that the engine is grounded to the car
chassis.
Charging system
1 Check the battery voltage on alternator 2.
2 Check that fuse 13 is intact and live.
3 Check that the charging lamp bulb is intact.
4 Check connectors and the wiring harness as
well as the generator's ground connection.
5 Check that terminal D+ on the alternator is live.
6 Start the engine and take a voltage reading be-
tween B+ on the generator and ground. Also
take a voltage reading between D+ on the gen-
erator and ground. The difference between the
two readings should not be more than O. 7
V.
Saab 9000
I