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IGNITION SYSTEMS
80 - 9
DIAGNOSTIC P R O C E D U R E S
INDEX
Page
Coolant Temperature Sensor Test
10
Failure To Start Test
9
General Information
9
Manifold Absolute Pressure (MAP) Sensor Test
. . 10
Page
Poor Performance Test . . . . . . . . . . . . . . . . . . . . .
10
Spark Advance ( S B E C Controlled) Test
10
Testing For Spark At Coil
9
GENERAL INFORMATION
For more information refer t o " O n B o a r d Diagnos-
t i c s " i n the General Diagnosis sections o f Group 14,
F u e l System.
TESTING FOR SPARK AT COIL
Remove coil secondary cable f r o m d i s t r i b u t o r cap.
H o l d end of cable about 6 m m (1/4-inch) away f r o m a
good engine ground (Fig. 1). C r a n k t h e engine and
check for a spark a t coil secondary cable.
Fig. 1 Checking for Spark
I f a spark occurs, i t m u s t be constant. I f i t is, con-
t i n u e to crank engine a n d w h i l e slowly m o v i n g the
coil secondary cable away f r o m ground, check for arc-
i n g a t the coil tower. I f a r c i n g occurs replace coil. I f
spark is not constant o r spark i s not present, proceed
to the failure to start test.
I f a good spark is produced t h e i g n i t i o n coil is pro-
ducing h i g h secondary voltage. Inspect t h e d i s t r i b u -
t o r rotor, cap, spark p l u g cables, and spark plugs. I f
t h e y are okay, the i g n i t i o n system is n o t t h e reason
w h y the engine w i l l not s t a r t . I t w i l l be necessary to
check the fuel system a n d engine mechanical items.
FAILURE TO START TEST
To prevent unnecessary diagnostic t i m e and w r o n g
test results, t h e " C h e c k i n g for Spark Test" should be
performed p r i o r t o t h i s test.
WARNING: S E T PARKING BRAKE OR BLOCK THE
DRIVE WHEELS BEFORE PROCEEDING WITH THIS
TEST.
(1) Determine t h a t sufficient battery voltage (12.4
volts) is present for t h e s t a r t i n g and i g n i t i o n sys-
tems.
(2) C r a n k t h e engine for 5 seconds w h i l e monitor-
i n g the voltage a t t h e coil positive t e r m i n a l (Fig. 2).
j ^ | § l g i » ^
TERMINAL
ENGINE GROUND
Fig. 2 Coil Terminals
• I f the voltage remains near zero d u r i n g the en-
t i r e period o f c r a n k i n g , refer to "On-Board Diagnos-
t i c s " i n t h e F u e l Injection section o f Group 14 to
check the single board engine controller (SBEC) and
auto shutdown relay.
• I f voltage is a t "near-battery" voltage and drops to
zero after 1-2 seconds o f c r a n k i n g , refer to "On-Board
Diagnostics" i n t h e F u e l Injection section of Group
14 to check t h e d i s t r i b u t o r reference pickup to SBEC
circuit.
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