878174 Mercury ROD, Throttle

Table 1
Diagnostic Codes Table    
Code and Description     Conditions which Generate this Code     System Response    
262-3 5 Volt Sensor DC Power Supply : Voltage Above Normal     The analog sensor supply voltage is above normal for two seconds.     The code is logged.
All sensors are set to default values.    
262-4 5 Volt Sensor DC Power Supply : Voltage Below Normal     The analog sensor supply voltage is below normal for two seconds.    
263-3 Digital Sensor Power Supply (8V Or 12V) : Voltage Above Normal     The digital sensor supply voltage is above normal for two seconds.    
263-4 Digital Sensor Power Supply (8V Or 12V) : Voltage Below Normal     The digital sensor supply voltage is below normal for two seconds.    System OperationThe Electronic Control Module (ECM) supplies a regulated voltage of 5.0 0.2 VDC to the following sensors:
Aftercooler temperature sensor
Atmospheric pressure sensor
Coolant pressure sensor
Coolant temperature sensor
Crankcase pressure sensor
Filtered engine oil pressure sensor
Filtered fuel pressure sensor
Turbocharger outlet pressure sensor
Left turbocharger inlet pressure sensor
Right turbocharger inlet pressure sensor
Unfiltered engine oil pressure sensor
Unfiltered fuel pressure sensorBoth the primary ECM and the secondary ECM can provide analog power and analog sensor reference to the engine sensors. In normal operation, the primary ECM has control of the engine. The primary ECM will provide the analog power and the analog sensor reference to the engine sensors. If the secondary ECM must take over control of the engine, the secondary ECM will provide analog power and the analog sensor reference to the engine sensors. The analog power and the analog sensor reference to the engine sensors is switched between the primary ECM and secondary ECM by the relay panel that is mounted on the left side of the engine. When the secondary ECM assumes control of the engine, the sinking driver for the "Backup ECM Active Lamp" is activated. When the sinking driver for the "Backup ECM Active Lamp" is activated, the reference relay and the 5 V power relay in the relay panel are energized. When the reference relay and the 5 V power relay are energized, the analog power and the analog sensor reference to the engine sensors are switched from the primary ECM to the secondary ECM.The supply voltage is routed to terminal A of each sensor connector. The analog sensor reference is routed to terminal B of each sensor connector. The sensor signal is routed to terminal C of each sensor connector. The ECM provides short circuit protection for the internal power supply. A short circuit to the battery will not damage the internal power supply.
Illustration 1 g00721067
Typical schematic 5 V supplyThe ECM supplies a regulated voltage of 8.0 0.4 VDC to the following sensors:
Left exhaust temperature sensor
Right exhaust temperature sensorBoth the primary ECM and the secondary ECM can provide digital power and digital sensor reference to the engine sensors. In normal operation, the primary ECM has control of the engine. The primary ECM will provide the digital power and the digital sensor reference to the engine sensors. If the secondary ECM must take over control of the engine, the secondary ECM will provide digital power and the digital sensor reference to the engine sensors.The power to the engine sensors is switched between the primary ECM and secondary ECM by the relay panel that is mounted on the left side of the engine. When the secondary ECM assumes control of the engine, the sinking driver for the "Backup ECM Active Lamp" is activated. When the sinking driver for the "Backup ECM Active Lamp" is activated, the 8 V power relay in the relay panel is energized. When the 8 V power relay is energized, the digital power to the engine sensors is switched from the primary ECM to the secondary ECM.The digital sensor reference to the engine sensors is switched between the primary ECM and secondary ECM by the "RSR" relay that is mounted in the control panel. When the secondary ECM assumes control of the engine, the sinking driver for the "Backup ECM Active Lamp" is activated. When the sinking driver for the "Backup ECM Active Lamp" is activated, the "RSR" relay in the control panel is energized. When the "RSR" relay is energized, the digital sensor reference to the engine sensors is switched from the primary ECM to the secondary ECM.The supply voltage for the sensors is routed from the ECM to terminal A of each sensor connector. The sensor return for the sensors is routed from the ECM to terminal B of each sensor connector. The ECM provides short circuit protection for the internal power supply. A short circuit to the battery will not damage the internal power supply.Note: The sensors are not protected from overvoltage. A short from the supply line to the +Battery may damage the sensors. If the diagnostic code 262-3 or the diagnostic code 263-3 is logged, it is possible that all of the sensors have been damaged. Repair the sensor supply and check for any active sensor diagnostic codes in order to determine if a sensor has failed.
Illustration 2 g02352405
ECM (1) J1/P1 connectors (2) J2/P2 connectors
Illustration 3 g02352407
P1 ECM connector (P1-29) Digital sensor return (P1-35) +8 V Sensor (P1-26) Right exhaust temperature (P1-30) Sensor return (P1-36) +5 V Sensor (P1-31) Engine oil temperature (P1-25) Left exhaust temperature (P1-17) Filtered fuel pressure
Illustration 4 g02352403
P2 ECM connector (P2-2) Right turbocharger compressor inlet pressure (P2-23) Turbocharger outlet pressure (P2-8) Filtered oil pressure (P2-20) Atmospheric pressure (P2-9) Coolant temperature (P2-15) Aftercooler temperature (P2-14) Left turbocharger compressor inlet pressure (P2-3) Unfiltered fuel pressureTest Step 1. Inspect the Electrical Connectors and the Wiring
Remove electrical power from the ECM.
Thoroughly inspect the J1/P1 ECM connector and the J2/P2 ECM connector. Inspect all of the connectors that are associated with the circuit.Refer to Troubleshooting,