Mercury MerCruiser MCM 454 Mag MPI Service Manual page 746

SERVICE MANUAL NUMBER 23
Section 5G - Trouble Code Diagnostics - 7.4L MPI
Table Of Contents
Clearing Trouble Codes
Clearing Codes Using Diagnostic Code
Tool (Non-Scan)
Clearing Codes Using Scan Tool
(Scan) . . . . . . . . . . . . . . . . . . . . . . . . .
Diagnostic Testing Without A Scan Tool
(Non-Scan) . . . . . . . . . . . . . . . . . . . . . . . .
Code 14 (1 of 3): Engine Coolant Tempera-
ture (ECT) Sensor Circuit (Non-Scan) Low
Temperature Indicated
Code 15 (1 of 3): Engine Coolant Tempera-
ture (ECT) Sensor Circuit (Non-Scan) High
Temperature Indicated
Code 21 (1 of 2): Throttle Position (TP)
Sensor Circuit (Non-Scan) Signal
Voltage High . . . . . . . . . . . . . . . . . . . .
Code 22 (1 of 2): Throttle Position (TP)
Sensor Circuit (Non-Scan) Signal
Voltage Low . . . . . . . . . . . . . . . . . . . .
Code 23 (1 of 3): Intake Air Temperature
(IAT) Sensor Circuit (Non-Scan) Low
Temperature Indicated
Code 25 (1 of 3): Intake Air Temperature
(IAT) Sensor Circuit (Non-Scan) High
Temperature Indicated
Code 33 (1 of 3): Manifold Absolute
Pressure (MAP) Sensor Circuit (Non-
Scan) High Signal Voltage
Code 34 (1 of 3): Manifold Absolute
Pressure (MAP) Sensor Circuit (Non-
Scan) Low Signal Voltage
Code 41 (1 of 3): Ignition Control (IC)
Circuit (Non-Scan) - Open IC Circuit 5G-25
Code 42 (1 of 3): Ignition Control (IC)
Circuit (Non-Scan) - Grounded IC Circuit,
Open Bypass Circuit, or Grounded
Bypass Circuit
Code 43 (1 of 2): Knock Sensor (KS)
Circuit Continuous Knock Detected
Code 44 (1 of 3): Knock Sensor (KS)
Circuit No Knock Detected
Code 51 (1 of 2): Calibration Memory
Failure (Non-Scan)
Index
90-861326--1 MARCH 1999
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FUEL SYSTEM
. . . . . . . . . . . . . . 5G-3
. . . . . . . . . . . . . . . . . 5G-3
5G-3
5G-4
. . . . . . . . . . . . 5G-4
. . . . . . . . . . . . 5G-6
5G-9
5G-11
. . . . . . . . . . . 5G-14
. . . . . . . . . . . 5G-16
. . . . . . . . 5G-19
. . . . . . . . 5G-22
. . . . . . . . . . . . . . . . . . 5G-28
5G-31
. . . . . . . 5G-33
. . . . . . . . . . . . . . 5G-36
TROUBLE CODE DIAGNOSTICS - 7.4L MPI
Diagnostic Testing Using A Scan Tool
Code 14 (1 of 3): Engine Coolant Tempera-
ture (ECT) Sensor Circuit (Scan) - Low
Temperature Indicated
Code 15 (1 of 3): Engine Coolant
Temperature (ECT) Sensor Circuit
(Scan) High Temperature Indicated
Code 21 (1 of 2): Throttle Position (TP)
Sensor Circuit (Scan) High
Signal Voltage . . . . . . . . . . . . . . . . . .
Code 22 (1 of 3): Throttle Position (TP)
Sensor Circuit (Scan) Low Signal
Voltage . . . . . . . . . . . . . . . . . . . . . . . . .
Code 23 (1 of 3): Intake Air Temperature
(IAT) Sensor Circuit (Scan) - Low
Temperature Indicated
Code 25 (1 of 2): Intake Air Temperature
(IAT) Sensor Circuit (Scan) High
Temperature Indicated
Code 33 (1 of 3): Manifold Absolute
Pressure (MAP) Sensor Circuit (Scan)
High Signal Voltage
Code 34 (1 of 3): Manifold Absolute
Pressure (MAP) Sensor Circuit (Scan) -
Low Signal Voltage
Code 41 (1 of 3): Ignition Control (IC)
Circuit (Scan) - Open IC Circuit
Code 42 (1 of 3): Ignition Control (IC)
Circuit (Scan) - Grounded IC Circuit,
Open Bypass Circuit, or Grounded
Bypass Circuit . . . . . . . . . . . . . . . . . .
Code 43 (1 of 2): Knock Sensor (KS)
Circuit (Scan) - Continuous Knock
Detected . . . . . . . . . . . . . . . . . . . . . . .
Code 44 (1 of 3): Knock Sensor (KS)
Circuit (Scan) -No Knock Detected
Code 51 (1 of 1): Calibration Memory
Failure (Scan) . . . . . . . . . . . . . . . . . . .
Code 52 (1 of 1): EEPROM Failure
(Scan) . . . . . . . . . . . . . . . . . . . . . . . . .
. . 5G-38
. . . . . . . . . . . 5G-38
5G-40
5G-43
5G-45
. . . . . . . . . . . 5G-47
. . . . . . . . . . . 5G-50
. . . . . . . . . . . . . . 5G-52
. . . . . . . . . . . . . . 5G-55
. . . . 5G-58
5G-60
5G-63
. 5G-65
5G-68
5G-69
Page 5G-1
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