Pontiac Fiero 1988 Service Manual page 634

DRIVEABILITY A N D EMISSIONS - FUEL INJECTION (PORT) 6 E 3 - A - 5 1
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CLEAR CODES.
• IDLE ENGINE FOR 1 MINUTE OR UNTIL CODE 42 SETS.
DOES CODE 42 S E T 7
CODE 42
ELECTRONIC SPARK TIMING
(EST) CIRCUIT
2.8L "P" SERIES (PORT)
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YES
• IGNITION " O F F " .
• DISCONNECT ECM CONNECTORS.
• IGNITION " O N " .
• OHMMETER SELECTOR SWITCH IN THE 1000 TO 2000
OHMS RANGE.
• PROBE ECM HARNESS CONNECTOR C K T 4 2 3 WITH AN
OHMMETER TO GROUND.
IT SHOULD READ LESS THAN 500 OHMS.
DOES
IT?
NO
CODE 42 INTERMITTENT. REFER TO
"DIAGNOSTIC AIDS" ON FACING PAGE.
YES
PROBE ECM HARNESS CONNECTOR CKT 424 WITH
A TEST LIGHT TO 12 VOLTS AND NOTE LIGHT.
NO
OPEN CKT 423, FAULTY CONNECTION
OR FAULTY IGNITION MODULE.
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LIGHT " O F F "
WITH OHMMETER STILL CONNECTED TO ECM HARNESS CKT
423 AND GROUND. AGAIN PROBE ECM HARNESS CKT 424
WITH THE TEST LIGHT CONNECTED TO 12 VOLTS. ( A S TEST
LIGHT CONTACTS CKT 424, RESISTANCE SHOULD SWITCH
FROM UNDER 500 TO OVER 5,000 O H M S , )
DOES
IT?
NO
LIGHT " O N "
DISCONNECT DIST. 4-WAY C O N N E C T O R . NOTE
OHMMETER THAT IS STILL CONNECTED TO CKT 423 AND
GROUND. RESISTANCE SHOULD HAVE GONE HIGH (OPEN
CIRCUIT).
DOES IT?
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YES
CKT 424 OPEN, FAULTY
CONNECTIONS OR FAULTY
IGNITION MODULE.
NO
CKT 423
SHORTED TO
GROUND.
DISCONNECT IGNITION MODULE 4-WAY CONNECTOR.
LIGHT " O N "
I
1_
CKT 424 SHORTED
TO GROUND.
LIGHT " O F F
FAULTY IGNITION
MODULE.
YES
RECONNECT ECM AND IDLE ENGINE FOR
ONE MINUTE OR UNTIL CODE 42 SETS.
DOES CODE SET?
YES
NO
FAULTY ECM
CODE 42 INTERMITTENT.
REFER TO "DIAGNOSTIC
AIDS" ON FACING PAGE.
CLEAR CODES AND CONFIRM " C L O S E D L O O P " OPERATION AND NO "SERVICE ENGINE S O O N " LIGHT.
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7 S 3 2 9 1 - 6 E