The relays
T6
and
T7
in the
engine compartment unit B1 manage the switching on of the fan
N11
at
two speeds: their coils are supplied by the ignition-controlled
line (15/54), while the power lines are protected by the fuses F6
and F7, of the engine compartment unit
B1
.
Both are energized by a control signal -
earth - coming from the engine control unit
M10, pins 7 and 8
of connector A, respecitvely.
If the engine coolant reaches a first temperature
level, or the fan linear sensor
K120 indicates to the control
unit M10 - pin 87 of connector A - that a certain pressure level
has been reached, the control unit M10 sends a signal - from pin
7 of connector A which energizes the fan 1st speed relay T6, which
then sends the supply to the fan N11 via the additional resistor
O10: the fan thus turns at the first speed (slow).
Linear sensor
K120 receives a power supply
and reference earth from the engine management control unit M10,
pins 37 and 10 of connector A.
If the coolant reaches a higher temperature
level, or the fan linear sensor
K120 indicates to the control
unit M10 that a higher pressure has been reached, the control unit
M10 sends a signal - from pin 89 of connector A - to the fan 2nd
speed relay T7, which sends the supply directly to the fan N11:
the fan then turns at the maximum speed.