Pontiac Fiero 1988 Service Manual page 616

DRIVEABILITY AND EMISSIONS - FUEL INJECTION (PORT) 6E3-A-33
CODE 21
THROTTLE POSITION SENSOR (TPS) CIRCUIT
(SIGNAL VOLTAGE HIGH)
2.8L "?" SERIES (PORT)
©
• THROTTLE CLOSED.
DOES " S C A N " DISPLAY TPS OVER 2.5 VOLTS?
YES
©
DISCONNECT SENSOR.
" S C A N " SHOULD DISPLAY TPS
BELOW .2 VOLTS (200mV).
DOES IT?
YES
NO
CODE 21 IS INTERMITTENT. IF NO
ADDITIONAL CODES WERE STORED,
REFER TO "DIAGNOSTIC AIDS" ON
FACING PAGE.
NO
©
PROBE SENSOR GROUND CIRCUIT WITH A
TEST LIGHT CONNECTED TO 12 VOLTS.
LIGHT "ON"
LIGHT " O F F "
FAULTY
CONNECTION
OR SENSOR
OPEN SENSOR
GROUND CIRCUIT
OR FAULTY ECM.
CKT417 SHORTED TO
VOLTAGE OR FAULTY ECM.
CLEAR CODES AND CONFIRM " C L O S E D L O O P " OPERATION AND NO "SERVICE ENGINE S O O N " LIGHT.
2-24-87
© 7 S 3 0 5 7 - 6 E