Pontiac Fiero 1988 Service Manual page 468

DRIVEABILITY AND EMISSIONS - FUEL INJECTION (TBI) 6E2-A-13
IGNITION "ON". ENGINE "OFF".
IS THE "S.E. S." LIGHT "ON"?
CHART A-2
NO ALDL DATA OR WON'T FLASH CODE 12
'SERVICE ENGINE SOON" LIGHT ON STEADY
2.5L "P" SERIES (TBI)
YES NO
GROUND DIAGNOSTIC TERM.
DOES LIGHT FLASH CODE 12?
SEE CHART A-1
NO
©
• IGNITION "OFF".
• DISCONNECT ECM CONNECTORS.
© IGNITION "ON" AND NOTE
"SERVICE ENGINE SOON" LIGHT.
©
©
LIGHT "OFF"
ZEZZZ
IGNITION "OFF".
RECONNECT ECM.
IGNITION "ON", ENGINE STOPPED.
DIAGNOSTIC TERMINAL NOT GROUNDED.
BACK PROBE ECM, CKT 451, WITH TEST
LIGHT TO GROUND.
NOCODE 12
©
CHECK PROM FOR PROPER INSTALLATION.
IF OK, REPLACE ECM USING ORIGINAL PROM.
RECHECK FOR CODE 12.
NO CODE 12
REPLACE PROM
YES
• IF PROBLEM WAS NO ALDL DATA:
© CHECK SERIAL DATA CKT461 FOR OPEN OR
SHORT TO GND. BETWEEN ECM AND ALDL
CONNECTOR. IF OK, IT IS A FAULTY ECM OR
PROM.
1
LIGHT "ON"
J
REPAIR SHORT TO
GROUND IN CKT419.
CODE 12
CHECK FOR OPEN IN ALDL DIAGNOSTIC
TERMS. "B" AND CKT 451 TO ECM.
IF OK, CHECK FOR OPEN IN ALDL TERM.
"A"TOECM.
CODE 12
n z z
SYSTEM OK
5-15-87
CLEAR CODES AND CONFIRM "CLOSED LOOP " OPERATION AND NO "SERVICE ENGINE SOON" LIGHT.
7 S 3 3 4 1
.
6 E