Chevrolet 1977 light duty truck, Service Manual

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Fig. 7A-4C- Colum n Shift Linkage ■ P Series
the transmission due to operation without
controls in fu ll detent. Such operation results in
reduced oil pressure and in turn partial
engagement o f the affected dutches. Partial
engagement o f the clutches with sufficient
pressure to cause apparent normal operation of
the vehicle will result in failure o f the clutches
or other internal parts after only a few miles of
operation.
D E T E N T D O W N S H IF T S W ITC H
1. Install switch as shown in Figure 7A-5C.
2. A fter installing the switch, press the switch
Fig. 7A-5C -Detent D ow nshift Switch
plu nger as far forward as possible. This presets the
switch for adjustm ent. T he switch will then adjust itself
with the first wide open throttle application o f the
accelerator pedal.
N E U TR A L S T A R T BAC K U P LA M P S W ITC H
A D J U S T M E N T
The neutral start backup lamp switch must be
adjusted so that the car will start in the park or neutral
position, but will not start in the other positions. For
replacem ent and adjustm ent refer to Section 8 o f this
manual.
DIAGNOSIS
SEQ U EN C E FOR D IA G N O S IS
1. Check and correct oil level.
2. Check detent switch.
3. Check and correct vacuum line and fittings.
4. Check and correct m anual linkage.
5. Install oil pressure gage.
6. Road test car.
a. Road test using all selective ranges, noting
w hen discrepancies in operation or oil pressure occur.
b. A ttem pt to isolate the unit or circuit involved
in the m alfunction.
c. If engine p erfo rm an ce indicates an engine
tune up is required, this should be p erfo rm ed before
road testing is completed or transmission correction
attempted. Poor engine p erform ance can result in rough
shifting or other malfunctions.
FLUID C H E C K IN G PROCEDURES
Refer to M ain ten an ce and Adjustm ent section for
fluid checking procedure.
FLUID LEAK D IA G N O S IS
D e te rm in in g S o urce o f Oil Leak
Before attem pting to correct an oil leak, the actual
source o f the leak must be determined. In m an y cases,
the source o f the leak can be deceiving due to "w ind
flow" around the engine and transmission.
The suspected area should be wiped clean o f all oil
before inspecting for the source o f the leak. Red dye is
used in the transmission oil at the assembly plant and
will indicate if the oil leak is from the transmission.