Saab SONETT III Service Manual page 47

Switching on and dimming
When- the headlights are raised, i.e. when the pullrod for
headlight operation is moved rearwards, the lever of the
microswitch is released and, provided that the ignition is
engaged, two current circuits are actuated. In one of these
circuits, current goes from the battery via the ignition
lock to the magnetic coil in relay (4) and then via the
microswitch to earth. In the other circuit, the current
goes the same way, except that in this case it passes
through the magnetic coil in relay (5).
The contacts in relays (4) and (5) are closed by the mag-
netic force, thus forming the following current circuits:
Circuit A
In this circuit, current passes from the battery via connec-
tions "30/51" and "87" on relay (5) to connection "86"
on the light relay and continues through coil (1) in the
relay to earth. The contact at coil (1) is now attracted to
its lower position and a new circuit is thus formed.
Circuit B
Current passes from the battery via connection "30" to
the contact (3) and continues either via "F" to high beam
or via "56a" to dipped beam. Contact (3) is actuated
mechanically by the contact at coil (2) and switches posi-
tion every time the coil is excited, which occurs according
to the next circuit.
Circuit D
—
Dimming circuit
The dimmer lever is moved rearwards, thus enabling
current to pass from the battery to connection "30" and
from thence through the coil (2) and connection "S" via
the dimmer switch to earth. The contact at coil (2) is
attractea and contact (3) switcnes position.
The reason why the light relay has been equipped with a
connection relay (5) is so that the current intensity through
the microswitch will be as low as possible. The light relay
is so designed that it can also be used for so-called high-
beam signalling, but on the Sonett III this possibility can
only be utilized if extra lights are installed, since the
standard headlights are lowered when switched off.
When a high-beam signal is given, which is done with the
dimmer lever and with the switch for the extra lights
turned on, current passes through coil (2) in the light
realy, whereas coil (1) remains inactivated. The contact
at coil (1) is thus in its upper position and that at coil
(2) in its lower position.
The current will then pass through the following circuit:
Battery — Connection "30" — Contact at (1) — Contact
at (2) — Connection "F" — Switch for extra I ights — coil
in relay (6) — earth. The contact in the relay is attracted
and current is passed to the extra lights.
LOCATION OF RELAYS, MICROSWITCHES AND FUSE BOX
1. Pullrod
2. Micros-witch
3. Light relay
4. Relay for automatic switching on of parking lights
5. Relay for engagement of light relay
6. Reiay for extra
I
ignts
7. Fuse box for headlights
Circuit D
Contact (3) is in its lefthand position, i.e. high beam is
switched on.
1. Current goes to the warning lamp for high beam.
2. If the switch for the extra lights is turned on, relay (6)
is activated.
3. If extra lights are installed, current is passed to these
from the battery via connections "30/51" and "87" on
relay (6).
Circuit E
When the microswitch is engaged, a current circuit is also
formed from the battery and via connections "30/51" and
"87" on relay (4) to the parking light. This is a safety
device which automatically turns on the parking and side
position lights as weil as the number lights if the switch for
these is not turned on when the headlights are raised.
300-2
SAAB
June 1970