Subaru XT 1988 Service Manual page 1205

6-1
ENGINE ELECTRICAL SYSTEM
2) Pulling up brush
Before assembling, press the brush down into the brush holder
with your finger and secure in that position by passing a
[2 mm (0.08 in) dia. length 4 to 5 cm (1.6 to 2.0 in)] wire
through the hole shown in the figure.
Be sure to remove the wire after reassembly.
L6-1671
Fig. 60
3) Heat the rear bracket [50 to 60°C (122 to 140° F)] and
press the rear bearing into the rear bracket. Then lubricate the
rear bracket.
4) After reassembly, turn the pulley by hand to check that
the rotor turns smoothly.
Distributor
DESCRIPTION
This distributor is equipped with a photoelectric crank-angle
sensor which trans.mits a crank-angle signal and a cylinder-
identification signal to the MPF I control unit.
24
Rotor head
L Rotor plate
L6-146B
Fig. 61
A signal processing unit, which is built into the distributor
housing, consists of LED and a photodiode. The rotor plate,
located between the LED and the photodiode, is secured to
the rotor shaft.
The rotor plate has four slits along its periphery through which
90° signals (in terms of distributor angle) are transmitted for
cylinder detection. In addition, there are three hundred and
sixty slits through which 1
0
signals (in terms of distributor
angle) are transmitted for crank-angle detection. Directly
above the rotor plate is the LED and below it is the photo-
diode.
When th,e ignition switch is turned "ON", the LED emits light
to the photodiode. The rotor plate turns as the engine starts.
The light emitted from the LED is then repeatedly interrupted
and transmitted through the slits by rotation of the rotor plate.
The "on-off" light signals (for cylinder detection and crank-
angle detection) are then converted into output signals which
are transmitted to the MPF I control unit.
The MPFI control unit determines optimum ignition timing in
response to these output signals and engine operating condi-
tions and transmits an ignition signal to the ignition coil.
This type of distributor is not equipped with a centrifugal
advance angle and a vacuum advance angle device.