855713A 4 Mercury SWITCH BOX

Table 1
Diagnostic Trouble Codes for the Valve Position Sensors    
J1939 Code    Description    Notes    
27-3     Engine Exhaust Gas Recirculation Valve Position : Voltage Above Normal     The Electronic Control Module (ECM) detects the following conditions:
The signal voltage from the position sensor on the NOx Reduction System (NRS) valve is greater than 4.8 VDC for 0.1 seconds.
If equipped, the warning lamp will come on. The ECM will log the diagnostic code. The NRS valve will be fully closed while the code is active.
The engine will be derated.    
27-4     Engine Exhaust Gas Recirculation Valve Position : Voltage Below Normal     The ECM detects the following conditions:
The signal voltage from the NRS valve position sensor is less than 0.2 VDC for 0.1 seconds.
If equipped, the warning lamp will come on. The ECM will log the diagnostic code. The NRS valve will be fully open while the code is active.
The engine will be derated.    
51-3     Engine Throttle Position : Voltage Above Normal     The ECM detects the following conditions:
The signal voltage from the position sensor on the engine intake throttle valve is greater than 4.8 VDC for 0.1 seconds.
If equipped, the warning lamp will come on. The ECM will log the diagnostic code. The engine intake throttle valve will be fully closed while the code is active.
The engine will be derated.    
51-4     Engine Throttle Position : Voltage Below Normal     The ECM detects the following conditions:
The signal voltage from the position sensor on the engine intake throttle valve is less than 0.2 VDC for 0.1 seconds.
If equipped, the warning lamp will come on. The ECM will log the diagnostic code. The engine intake throttle valve will be fully closed while the code is active.
The engine will be derated.    
3488-3     Aftertreatment #1 Air Pressure Actuator Position : Voltage Above Normal     The ECM detects the following conditions:
The signal voltage from the position sensor on the combustion air valve is greater than 4.85 VDC for 8 seconds.
If equipped, the warning lamp will come on. The ECM will log the diagnostic code.
The engine will be derated.    
3488-4     Aftertreatment #1 Air Pressure Actuator Position : Voltage Below Normal     The ECM detects the following conditions:
The signal voltage from the position sensor on the combustion air valve is less than 0.2 VDC for 8 seconds.
If equipped, the warning lamp will come on. The ECM will log the diagnostic code.
The engine will be derated.    The following conditions must exist before any of the preceding codes will become active:
The ECM has been powered for at least 2 seconds.
There are no active 3509 codes.
There are no active 168 codes.Use this procedure in order to troubleshoot the position sensors for the following valves:
NRS valve
Engine intake throttle valve
Combustion air valve for the Aftertreatment Regeneration Device (ARD)Each position sensor is integral in the associated valve. If the following procedure indicates a fault with the position sensor, then the entire valve must be replaced.The following background information is related to this procedure:The troubleshooting procedures for the diagnostic codes of each position sensor are identical. The 5 VDC sensor supply provides power to all 5 VDC sensors. The ECM supplies 5.0 VDC to terminal "5" of the engine intake throttle valve connector and to terminal "1" of the other valve connectors. The sensor common from the ECM connector goes to terminal "3" of the engine intake throttle valve connector. The sensor common from the ECM connector goes to terminal "2" of the other valve connectors. The sensor supply is output short circuit protected. A short circuit to the battery will not damage the circuit inside the ECM. The signal voltage from terminal "4" of the engine intake throttle valve is supplied to the appropriate terminal at the P2 ECM connector. The signal voltage from terminal "3" of the other valves is supplied to the appropriate terminal at the P2 ECM connector.Pull-up VoltageThe ECM continuously outputs a pull-up voltage on the circuit for the sensor signal wire. The ECM uses this pull-up voltage in order to detect an open in the signal circuit. When the ECM detects a voltage above a threshold on the signal circuit, the ECM generates an open circuit diagnostic code (XXXX-3) for the sensor.If the sensor is disconnected, pull-up voltage at the sensor connector indicates that the wires are not open or shorted to ground. If the sensor is disconnected , the absence of pull-up voltage indicates an open in the signal wire or a short to ground. If the sensor is disconnected and the voltage is different from pull-up voltage, the signal wire is shorted to another wire in the harness.
Illustration 1 g02186415
Typical example of the schematic for the position sensors
Illustration 2 g01981373
Typical view of the pin locations on the P2 connector for the position sensors (3) Engine intake throttle valve position sensor signal (15) NRS valve position sensor signal (16) Combustion air valve position sensor signal (45) Combustion air valve position sensor 5 VDC supply (46) Engine intake throttle valve, NRS valve position sensors 5 VDC supply (55) Combustion air valve position sensor ground (56) Engine intake throttle valve, NRS valve position sensors ground
Illustration 3 g02186473
Typical view of the pin locations for the valve position sensors on the connectors from the engine to the Clean Emissions Module (CEM) (1) 5 VDC supply (2) Combustion air valve position sensor ground (9) Combustion air valve position sensor signal
Illustration 4 g01955200
Typical example of the connector for the combustion air valve (1) 5 VDC supply (2) Position sensor ground (3) Position sensor signal
Illustration 5 g02157941
Typical example of the connector for the engine intake throttle valve (3) Position sensor ground (4) Position sensor signal (5) 5 VDC supply
Illustration 6 g02854698
Typical example of the connector for the NRS valve (1) 5 VDC supply (2) Position sensor ground (3) Position sensor signal