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(377)
ELECTRICAL SYSTEMS
INSTRUMENTS
10-101
the flange of unit. Attach
spring
clips to the
free ends of both wires.
a.
Test
of
Da
sh Unit
1.
With ignition switch turned off, discon-
nect the tank wire (white with black parallel
tracers) from dash un
it
terminal. Connect the
red tester wire to this
terminal
and connect
black tester wire to any convenient ground on
car. Make sure that the other wire attached to
dash unit has a tight connection.
2. Turn ignition switch on, then move tester
arm up and down against the stops.
If
dash unit is okay, the pointer will move
freely
from "Empty" to "Full" with movement of
tester
arm,
indicating that the
trouble
is
in
wiring or tank unit.
If
pointer does not move,
or only moves part way, the dash unit is fau
lty
and should be replaced.
3. Turn ignition switch off.
If
dash unit is
okay, reconnect wire to terminal stud, being
careful that the terminal of this wire does not
come in contact with the other dash unit ter-
minal, which would result in damage to tank
unit
rheostat.
b.
Test
of
Ta
nk Unit Wiring
1. With ignition switch turned off, discon-
nect tank unit wire at bayonet connector in left
rear corner of rear compartment. Connect the
red tester wire to the wire r
unning
to dash unit
and ground the black tester wire on car.
2.
Turn ignition switch on, then move tester
arm up and down against stops while dash unit
is being observed.
If
wiring is okay, dash unit
pointer will move freely from "Empty" to
"Full" with movement of tester arm, indicating
that the trouble is in tank unit or the short
wire leading to it.
3.
If,
on the test, dash unit reads "Empty"
at all times or the reading is noticeably lower
than during the test of dash unit, look for a
ground in the wiring between dash unit and
bayonet
connector.
If
dash unit reads above
"Full" at all times or if it reads higher at
"Empty" and "Full" than readings obtained on
dash unit test, look for points of high resist-
ance such as dirty
connections,
broken wire
strands, or open circuit.
c.
Test of Ta
nk Unit
1. If
tests given
above indicate
that the
trouble is in the tank unit, remove the gasoline
tank (par. 3-15) so that the tank unit may be
cleaned and tested.
2. Before removing unit from gasoline tank
clean away all dirt that has collected around the
tank unit, and note whether the insulation was
in proper position over the terminal and
wire.
Road dirt, particularly calcium chloride, may
have caused an electrical leak that threw the
tank unit out of
calibration.
3. After thorough cleaning and removal of
tank unit, connect it to ground and to wire
leading to dash unit, and test in the same man-
ner as when using tester.
If
tank unit tests
okay it should be reinstalled in tank, otherwise
it should be replaced with a new unit. When in-
stalling tank unit make certain that insulation
is folded over the terminal and snapped over
wire.
10-68
SPEEDOMETER
The AC pointer type speedometer head, lo-
cated in the center of instrument cluster, has
a magnetic type speed indicator and a gear
driven odometer. The total mileage odometer
incorporates five figure wheels, and the trip odo-
meter incorporates four figure wheels, the right
hand wheel indicating in one-tenths of a mile.
The trip odometer reset knob is located on
the lower edge of instrument panel. On S
eries
40
it is just to right of steering column and on
Series
50-70
it is just to left of steering column.
A quick reset may be obtained by pushing knob
up and turning it to the right. Turning the
knob to the left resets one-tenth mile at a time.
The speedometer head is driven by a flexible
cable, inclosed on a casing, which is driven by
worm gears in the transmission rear bearing
retainer. See paragraph 4-24.
a
.
Te st of Speedometer
Head
Most cable breakages are caused by tightness
in the speedometer head. Tightness or binding
in the head may also cause wavering of the
pointer. The speedometer head may be tested
for tightness or binding as follows:
1.
Obtain a short piece of
speedometer
cable (3" to 4" long) with a tip to fit the
speedometer
head.
A piece of broken cable may
be used.
2. With
speedometer head
in place but with
the cable and casing disconnected, insert the
test cable in the speedometer socket.
3. Spin the test cable between thumb and
finger three or four turns.
If
test cable turns
hard or shows any tendency to bind at all, there
is trouble in the head and it should be removed
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