Chevrolet Light Duty Truck 1973, Service Manual

Page: 513 / 979

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COMPLAINT
Engine Stalls at Idle
Excessive Creep at Idle
High Idle Speed
Dieseling
C h e c k for free m o v e m e n t o f
plunger.
C h eck for in c o rre c tly adjusted
plun ger (o u t to o far).
S o len o id should de-energize w ith
ignition off.
C A U SE:
M alfu n ctio n
in Idle
S t o p So lenoid
COMPLAINT
Vacuum at all Times
Transmission Switch M alfun ction
With engine w a rm an d run ning,
put transm ission in low forw ard
g e a r , t h e a d v a n c e solenoid
should be de-energized. If sole­
noid energizes, rem o ve sw itch
co n n e c tio n replace transm ission
switch if solenoid de-energizes.
Step 1
In operative Vacuum
Advance Solenoid
Check v a c u u m at source, then
connect v a c u u m gauge to a d ­
vance u n it p o rt. W ith 12 volts
applied to solenoid, solenoid
should be energized (v a c u u m to
distributor). P ro ceed to S tep 2 if
solenoid is n o t at fault.
Step 2
Inoperative Tim e Relay
1. R em o v e te m p e ra tu re sw itch
c o n n e c to r.
2. C h eck relay to m a k e sure
th a t it is c ool, th e n tu rn igni­
tio n on.
3. S o len o id sh o u ld energize for
2 0 second s an d th e n d e ­
energize. If it d o es no t d e ­
energize, rem o ve b lue lead
fro m tim e relay. S o len o id
will de-energize if relay is at
fault. P ro ceed to S te p 3 if
relay is n o t at fault.
C A U S E :
M a lfu n ctio n in T C S S y ste m C o m p o n e n t
C heck for: B low n fuse L oose c o n n e c tio n s B roken
wire B ro k en or d isc o n n e c te d hoses P ro p e r g ro u n d
at all c o m p o n e n t s Pro p er ro u tin g o f hoses.
COMPLAINT
Poor High Gear Performance
S tum ble-Stall on Cold Start
Excessive Fuel Consumption
Deceleration Exhaust “ Pop”
Step 3
Inoperative Tem perature
Switch
O n a cold engine th e v a c u u m
a dvance so len o id sh o u ld be e n e r­
gized, if no t - g ro u n d th e wire
fro m the cold term in a l o f the
te m p e ra tu re sw itch. If solenoid
energizes, replace th e t e m p e r a ­
tu re sen ding unit. P ro c ee d to
S tep 4 if u n it is n o t at fault.
Step 4
Inoperative Transmission
S w itch
W ith engine w a rm an d ru n n in g ,
p u t transm ission in reverse on
H y d ra-m a tic o r high o n m a n u a ls,
s olenoid sh o u ld be energized.
If n o t rem o ve a n d g ro u n d
c o n n e c to r at s w i t c h - replace
sw itch if so le n o id energizes.
Fig. 19e—Trouble Shooting Guide (V8 Engine)
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