Mercury 305 CID - Page 648

ELECTRONIC FUEL INJECTION (MULTI-PORT AND THROTTLE BODY) - 5E-10790-823225--1 1096
Code 33: MAP Circuit (Scan)
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• IF ENGINE IDLE IS ROUGH, UNSTABLE, OR
INCORRECT, CORRECT CONDITION
BEFORE USING CHART, SEE THE
TROUBLESHOOTING SECTION.
• ENGINE IDLING.
DOES SCAN TOOL DISPLAY A MAP
SENSOR VOLTAGE OF LESS THAN 1 VOLT
OR GREATER THAN 4 VOLTS?
YES NO
• IGNITION “OFF.”
• CONNECT DVOM BETWEEN
MAP SENSOR HARNESS
TERMINAL “C” AND A.
• IGNITION “ON.”
IS VOLTAGE OVER 4 VOLTS?
CODE 33 IS INTERMITTENT, IF NOT
ADDITIONAL CODES WERE STORED,
REFER TO “DIAGNOSTIC AIDS” ON
FACING PAGE.
NOYES
• IGNITION “OFF.”
• DISCONNECT MAP SENSOR ELECTRICAL
CONNECTOR.
• START ENGINE.
• “SCAN” TOOL SHOULD DISPLAY A
VOLTAGE OF LESS THAN 1 VOLT.
DOES IT?
VOLTAGE LESS THAN 1 VOLT.
• IGNITION “OFF.”
• DISCONNECT MAP SENSOR ELECTRICAL
CONNECTOR.
• JUMPER MAP SENSOR HARNESS TERMINALS
“C” AND “B” TOGETHER.
• START ENGINE.
DOES SCAN TOOL DISPLAY MAP SENSOR
VOLTAGE GREATER THAN 4 VOLTS?
NO YES
CHECK FOR MAP
SENSOR SIGNAL CKT
432 SHORTED TO
GROUND. IF OK,
REPLACE MAP
SENSOR.
VOLTAGE GREATER THAN 4 VOLTS.
NOYES
NO YES
CKT 416 OPEN FAULTY
ECM CONNECTION
OR
FAULTY ECM.
OPEN SENSOR
GROUND CIRCUIT
MAP SENSOR SIGNAL
CKT 432 OPEN OR
SHORTED TO
GROUND
OR
FAULTY CONNECTION
AT ECM
OR
FAULTY ECM.
FAULTY MAP SENSOR
• IGNITION “OFF.”
• CONNECT DVM
BETWEEN MAP
SENSOR HARNESS
TERMINAL “A”
AND “C”.
• IGNITION “ON.”
• VOLTAGE SHOULD
BE GREATER THAN
4 VOLTS.
IS IT?
• IGNITION “OFF.”
• MAP SENSOR
SIGNAL CKT 432
SHORTED TO
VOLTAGE
OR
FAULTY ECM
CONNECTIONS
OR
FAULTY ECM.
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