Buick LeSabre 1965 Service Manual page 674

1 0 - 1 0 4 DESCRIPTION
ELECTRICAL SYSTEMS
CASH S W I T C H - L 0 SPEED
OFF LO HI
IROJIT BREAKER
BLACK WITH WHITE JBTRIPE
RELAY
SWITCH CCNTCCTS
MJTOR SECTION
CIRCUIT C O D E
Relay Coil Circuit
Power Supply t o Motor
Windings
Figure 10-110—Wiring Diagram - Low Speed Operation
the 12V feed (black with pink
stripe) to the wiper motor wind-
ings is completed and the wiper
motor starts.
When the wiper motor first
starts, only the gear rotates. The
other gear assembly parts (drive
pawl, lock pawl, drive plate and
shaft, plus the crank arm) are
unlocked from the gear and are
prevented from rotating with the
gear because the drive pawl ex-
tends into the magnet switch slot.
Refer to Figure 10-109.
Since the gear rotates independ-
ently during this stage of the
"start up", and since the crank
arm or output shaft extends
through the gear shaft off center
a cam action results between the
output shaft and gear shaft. This
cam action causes the drive pawl
to move out of the relay switch
slot. After the gear has rotated
approximately 180°, the spring
loaded drive and lock pawl guide
pins snap into their respective
pockets in the gear locking the
drive or output shafts and re-
lated parts to the gear. The com-
plete gear mechanism is now in
its normal run position, and the
gear, drive pawl, lock pawl, drive
plate and shaft assembly and
crank arm rotate as a unit. See
Figure 10-111.
3. Wiper On High Speed. Turning
the wiper dash switch to the high
speed position opens the shunt
field circuit to ground at the dash
switch. However, the shunt field
c i r c u i t is then completed to
ground through the resistor lo-
cated on the w i p e r terminal
board. See Figure 10-112.
With the shunt field circuit com-
pleted to ground through the re-
sistor, the wiper will run at high
speed. (Crank arm RPM approxi-
mately 70 @ 12 volts.)
4. Shutting Wiper Off. Moving the
dash switch to the off position
opens the relay coil circuit to
ground at the dash switch. With
the relay coil circuit open, the
spring loaded relay latch arm
moves out into the path of the
gear assembly drive pawl. See
Figure 10-111.
The relay switch contacts are
still closed at this stage of oper-
ation, so the circuit to the wiper
motor is still completed. Thus
the wiper motor and gear mecha-
nism c o n t i n u e s to run. The
continuing rotation of the gear as-
sembly causes the drive pawl to
engage the latch arm. See Fig-
ure 10-113. This action unlocks
the drive pawl, lock pawl, drive
plate and shaft assembly, and
crank arm from the gear which
prevents them from rotating with
the gear. However, since the re-
lay switch contacts are s t i l l
closed, the motor continues to
run and the gear continues to ro-
tate. Since the drive shaft ex-
tends through the gear shaft off
center a cam action results. The