851849 Mercury CLIP

Table 1
Diagnostic Codes for the Sensor Supply
J1939 Code CDL Code Code Description
(code descriptions may vary) Comments
678-3 41-3 8 Volt DC Supply voltage above normal The ECM detects the following conditions:
The 8 V supply is more than 8.8 V for more than one second.
The ECM has been powered for more than 3 seconds.
Diagnostic code 168-3 is not active.
The ECM will log the diagnostic code.
The engine may be limited to low idle.
678-4 41-4 8 Volt DC Supply voltage below normal The ECM detects the following conditions:
The 8 V supply is less than 7.2 V for more than one second.
The ECM has been powered for more than 3 seconds.
Diagnostic code 168-4 is not active.
The ECM will log the diagnostic code.
The engine may be limited to low idle.
An active diagnostic code may not cause any noticeable effect on engine response unless the voltage drops below 6.5 V.
3509-3 262-3 5 Volt Sensor DC Power Supply voltage above normal The Electronic Control Module (ECM) detects the following conditions:
The 5 V supply for the sensors is greater than 5.16 V for more than one second.
The ECM has been powered for at least 3 seconds.
Diagnostic code 168-3 is not active.
The ECM sets all of the sensors on the 5 V circuit to the default values.
The engine will be derated.
3590-4 262-4 5 Volt Sensor DC Power Supply voltage below normal The ECM detects the following conditions:
The 5 V supply for the sensors is less than 4.84 V for more than one second.
The ECM has been powered for at least 3 seconds.
Diagnostic code 168-4 is not active.
The ECM sets all of the sensors on the 5 V circuit to the default values.
The engine will be derated.
Follow the troubleshooting procedure in order to identify the root cause of the fault. The following background information is related to this procedure:The ECM supplies regulated +5 V to the following sensors:
Intake manifold air pressure sensor
Fuel pressure sensor
Engine oil pressure sensorThe ECM supplies regulated +8 V to the following sensors:
Primary speed/timing sensor
Secondary speed/timing sensorNote: Refer to the Electrical Schematic for the application for information regarding components that are connected to the 5 V and 8 V supplies on the J1/P1 connector.A diagnostic code can be caused by the following conditions:
A short circuit in the harness
A short circuit to a voltage that is higher than 5.16 V
A faulty sensor
A faulty ECM
An open circuit in the harness
Illustration 1 g03682449
5 V supply circuit
Illustration 2 g03682459
8 V supply circuit
Note: Refer to the Electrical Schematic for the application for information regarding components that are connected to the 5 V and 8 V supplies on the J1/P1 connector.
Illustration 3 g03375608
P2 pin locations for the sensor supply circuits
(10) 8 V supply
(38) Intake manifold pressure sensor return
(39) Oil pressure sensor return
(40) Fuel rail pressure sensor return
(46) Intake manifold air pressure sensor 5 V supply
(47) Oil pressure sensor 5 V supply
(48) Fuel rail pressure sensor 5 V supply
Illustration 4 g03374231
Fuel rail pressure sensor
(1) Ground
(2) Signal
(3) 5 V Supply
Illustration 5 g01170310
Typical example of an engine pressure sensor
(1) 5 V Supply
(2) Ground
(3) Signal
Illustration 6 g01212995
Typical example of a speed/timing sensor
(1) 8 V supply
(2) Signal
Table 2
Troubleshooting Test Steps Values Results
1. Determine the Code
A. Connect the electronic service tool to the service tool connector. Refer to Troubleshooting, "Electronic Service Tools", if necessary.
B. Turn the keyswitch to the ON position.
C. Determine if a diagnostic trouble code is present.
Diagnostic Codes
Result: A -3 or -4 code is present.
Note which sensor supply has the active diagnostic code.
Proceed to Test Step 2.
2. Check for a Failed Sensor
A. Connect to the electronic service tool.
B. Turn the keyswitch to the ON position.
C. Disconnect a sensor on the suspect sensor supply circuit.
D. Monitor the electronic service tool while the sensor is disconnected to see if the active code changes to logged.
E. Connect the suspect sensor to the wiring harness
F. Repeat steps C through E for each sensor on the suspect sensor supply.
Note: Refer to the Electrical Schematic for the application for information regarding components that are connected to the 5 V and 8 V supplies on the J1/P1 connector.
Failed Sensor
Result: The suspect sensor supply active code changes to logged when a sensor is unplugged.
Repair: Replace the failed sensor.
Verify that the repair resolved the problem.
Result: The suspect sensor supply active code remains active after all sensors on the