3500B Marine Engines Caterpillar

The Analog Sensor Supply provides power to all analog sensors. The Electronic Control Module (ECM) supplies 5.0 ± 0.2 VDC from the ECM connector J1/P1 to each analog sensor connector. The sensor return line connects to the ECM connector J1/P1. The analog sensor supply is output short circuit protected. A short circuit to the battery will not damage the circuit inside the ECM.

Note: The Analog Sensors are not protected from overvoltage. A short from the analog supply line to the + Battery supply may damage the sensors. If CID-FMI 262-03 is logged, it is possible that all of the analog sensors have been damaged. Repair the Analog Sensor Supply and check for any "ACTIVE" sensor diagnostic codes in order to determine if a sensor has failed.

Note: The Engine Monitoring System can be programmed by dealers and/or customers. Dealers and/or customers can monitor customized warnings, derates, shutdown override setpoints, and delay times using the Caterpillar Electronic Technician (ET). Customized parameters may affect the behavior of the ECM. The behavior of the ECM may vary from the description that is given in this system operation section. You may refer to the diagnostic procedure Troubleshooting, "Engine Monitoring System" in order to determine if there are any parameters that are affecting engine operation.

The following list contains a description of the analog sensors that are found on the engine.

Aftercooler Temperature Sensor - The ECM uses the signal from the sensor to monitor changes in system temperature. The ECM makes adjustments to the system's operating parameters as the temperature changes. This allows the engine to operate at optimal performance through a wide range of operating temperatures. The operating range of the sensor is −40 °C to 120 °C (−40 °F to 248 °F).

Coolant Temperature Sensor - Cold Mode operation improves the engine starting ability. Cold Mode operation helps to control white smoke during cold starts. Cold Mode operation helps to improve warm up time of the engine. In Normal Mode, injection timing is varied as a function of engine speed and load. The process of combustion is improved by controlling the injection timing in Cold Mode. Transient engine response is slower in Cold Mode operation. Cold Mode operation is activated when the engine water temperature is below 60 °C (140 °F). Cold Mode operation will remain active until water temperature rises above 63 °C (145 °F). The engine will alternate between Cold Mode and Normal Mode during operation, as engine temperature fluctuates. The operating range of the sensor is −40 °C to 120 °C (−40 °F to 248 °F).

Filtered Fuel Pressure Sensor - The sensor is used in conjunction with the Unfiltered Fuel Pressure sensor to determine the restriction across the fuel filters. The sensor output is a DC voltage that varies with filtered fuel pressure between 0.2 VDC and 4.8 VDC. The sensor is located on the end cap of the fuel filter housing. The operating range of the sensor is 0.0 kPa to 1090 kPa (0.0 psi to 158 psi). The ECM calibrates the sensor within the first five seconds after power is applied to the ECM. The ECM checks the sensor value against an acceptable pressure range. If the pressure value is not in this range the previous calibration will be used. A manual calibration of the sensor should be done if the sensor or the ECM has been replaced. Refer to the calibration procedure Troubleshooting, "Anolog Sensor - Calibrate".

Unfiltered Fuel Pressure Sensor - The sensor is used in conjunction with the Filtered Fuel Pressure sensor to determine the restriction across the fuel filters. The sensor output is a DC voltage that varies with unfiltered fuel pressure between 0.2 VDC and 4.8 VDC. The sensor is located on the end cap of the fuel filter housing. The operating range of the sensor is 0.0 kPa to 1090 kPa (0.0 psi to 158 psi). The ECM calibrates the sensor within the first five seconds after power is applied to the ECM. The ECM checks the sensor value against an acceptable pressure range. If the pressure value is not in this range the previous calibration will be used. A manual calibration of the sensor should be done if the sensor or the ECM has been replaced. Refer to the calibration procedure Troubleshooting, "Anolog Sensor - Calibrate".

Filtered Engine Oil Pressure Sensor - The sensor is used in conjunction with the Unfiltered Engine Oil Pressure sensor in order to determine the restriction across the engine oil filters. The ECM uses this sensor to detect low engine oil pressure which may indicate a failed engine oil pump or low engine oil pressure. The signal is compared with a map of engine oil pressure versus engine rpm which is stored in the ECM. The sensor output is a DC voltage that varies with engine oil pressure between 0.2 VDC and 4.8 VDC. The sensor is located downstream of the engine oil filter. The operating range of the sensor is 0.0 kPa to 1090 kPa (0.0 psi to 158 psi). The ECM calibrates the sensor within the first five seconds after power is applied to the ECM. The ECM checks the sensor value against an acceptable pressure range. If the pressure value is not in this range the previous calibration will be used. A manual calibration of the sensor should be done if the sensor or the ECM has been replaced. Refer to the calibration procedure Troubleshooting, "Anolog Sensor - Calibrate".

Unfiltered Engine Oil Pressure Sensor - The sensor is used in conjunction with the Filtered Engine Oil Pressure sensor to determine the restriction across the engine oil filters. The sensor output is a DC voltage that varies with unfiltered engine oil pressure between 0.2 VDC and 4.8 VDC. The sensor is located before the engine oil filters in the oil passage of the engine oil filter housing. The operating range of the sensor is 0.0 kPa to 1090 kPa (0.0 psi to 158 psi). The ECM calibrates the sensor within the first five seconds after power is applied to the ECM. The ECM checks the sensor value against an acceptable pressure range. If the pressure value is not in this range the previous calibration will be used. A manual calibration of the sensor should be done if the sensor or the ECM has been replaced. Refer to the calibration procedure Troubleshooting, "Anolog Sensor - Calibrate".

Left Turbocharger Compressor Inlet Pressure Sensor - The sensor is used in conjunction with the Atmospheric Pressure Sensor to determine if the engine air filter is plugged. The sensor indicates if the left turbocharger compressor inlet has a restriction. The sensor output is a DC voltage between 0.2 VDC and 4.8 VDC that varies with left turbocharger compressor inlet pressure. The operating range of the sensor is 0.0 kPa to 111 kPa (0.0 psi to 16 psi). The ECM calibrates the sensor within the first five seconds after power is applied to the ECM. The ECM checks the sensor value against an acceptable pressure range. If the pressure value is not in this range the previous calibration will be used. A manual calibration of the sensor should be done if the sensor or the ECM has been replaced. Refer to the calibration procedure Troubleshooting, "Anolog Sensor - Calibrate".

Right Turbocharger Compressor Inlet Pressure Sensor - The sensor is used in conjunction with the Atmospheric Pressure Sensor to determine if the engine air filter is plugged. The sensor indicates if the right turbocharger compressor inlet has a restriction. The sensor output is a DC voltage between 0.2 VDC and 4.8 VDC that varies with right turbocharger compressor inlet pressure. The operating range of the sensor is 0.0 kPa to 111 kPa (0.0 psi to 16 psi). The ECM calibrates the sensor within the first five seconds after power is applied to the ECM. The ECM checks the sensor value against an acceptable pressure range. If the pressure value is not in this range the previous calibration will be used. A manual calibration of the sensor should be done if the sensor or the ECM has been replaced. Refer to the calibration procedure Troubleshooting, "Anolog Sensor - Calibrate".

Turbocharger Compressor Outlet Pressure Sensor - The sensor is used to obtain boost pressure. Boost pressure is used to control the ratio of fuel to air during acceleration. The ECM limits the amount of fuel that is injected, based upon inlet manifold pressure. Information in the ECM defines the relationship between the manifold pressure and the fuel ratio control limit (FRC). The operation is similar to the fuel ratio control on an engine with a mechanical governor. The sensor output is a DC voltage between 0.2 VDC and 4.8 VDC that varies with turbocharger outlet pressure. The operating range of the sensor is 0.0 kPa to 452 kPa (0.0 psi to 65 psi). The ECM calibrates the sensor within the first five seconds after power is applied to the ECM. The ECM checks the sensor value against an acceptable pressure range. If the pressure value is not in this range the previous calibration will be used. A manual calibration of the sensor should be done if the sensor or the ECM has been replaced. Refer to the calibration procedure Troubleshooting, "Anolog Sensor - Calibrate".

Atmospheric Pressure Sensor - The sensor is used to provide an atmospheric pressure signal to the ECM. If the Atmospheric Pressure Sensor should fail, the Right Turbocharger Compressor Inlet Pressure Sensor is used as a substitute. If the Right Turbocharger Compressor Inlet Pressure Sensor should fail, the Left Turbocharger Compressor Inlet Pressure Sensor is used as a substitute. The sensor output is a DC voltage between 0.2 VDC and 4.8 VDC that varies with atmospheric pressure. The operating range of the sensor is 0.0 kPa to 111 kPa (0.0 psi to 16 psi). The sensor is used to calibrate the other pressure sensors within the first five seconds after power is applied to the ECM. The ECM checks the sensor value against an acceptable pressure range. If the pressure value is not in this range a diagnostic message will be generated and the engine may be derated. A manual calibration of the sensor should be done if the sensor or the ECM has been replaced. Refer to the calibration procedure Troubleshooting, "Anolog Sensor - Calibrate".

Crankcase Pressure Sensor - The sensor is used in conjunction with the Atmospheric Pressure Sensor to determine if the engine crankcase pressure is too high. The Atmospheric pressure is subtracted from the Absolute crankcase pressure. The difference between the Atmospheric pressure and the Absolute crankcase pressure is the Differential Crankcase Pressure. The sensor output is a DC voltage between 0.2 VDC and 4.8 VDC that varies with crankcase pressure. The operating range of the sensor is 0.0 kPa to 111 kPa (0.0 psi to 16 psi). The ECM calibrates the sensor within the first five seconds after power is applied to the ECM. The ECM checks the sensor value against an acceptable pressure range. If the pressure value is not in this range the previous calibration will be used. A manual calibration of the sensor should be done if the sensor or the ECM has been replaced. Refer to the calibration procedure Troubleshooting, "Anolog Sensor - Calibrate".

Illustration 1	g00599048
Typical schematic

Test Step 1. Check for Connector Damage.

1. Turn the circuit breaker for the battery to the OFF position.

2. Turn the Engine Control Switch (ECS) to the OFF/RESET position.

3. Thoroughly inspect the ECM connectors J1/P1 and J2/P2. Inspect all of the other connectors. Refer to Troubleshooting, "Inspecting Electrical Connectors" for details.

4. Perform a 45 N (10 lb) pull test on each of the wires in the ECM connector that are associated with the circuit.

5. Check the ECM connector (allen head screw) for the proper torque of 2.25 ± 0.25 N·m (20 ± 2 lb in).

6. Check the customer connector (allen head screw) for the proper torque of 2.25 ± 0.25 N·m (20 ± 2 lb in).

7. Check the harness and the wiring for abrasion and for pinch points.

Expected Result:

All connectors, pins, and sockets are completely coupled and/or inserted, and the harness and wiring should be free of corrosion, of abrasion or of pinch points.

Results:

• OK - The connectors and wiring are okay. Proceed to Test Step 2.

• Not OK - The connectors and/or wiring need repair.

  Repair: Repair the connectors or wiring and/or replace the connectors or wiring.

  STOP

Test Step 2. Check the Harness for Shorts.

1. Disconnect the Primary ECM connector J1/P1. Disconnect all of the analog sensors.

2. Measure the resistance between the analog supply P1-36 and the analog return P1-30.

3. Measure the resistance between P1-36 and P1-5.

4. Measure the resistance between P1-36 and P1-11.

5. Measure the resistance between P1-36 and P1-29.

6. Measure the resistance between P1-36 and engine ground.

7. Measure the resistance between P1-30 and engine ground.

Expected Result:

The resistance should be more than 20,000 Ohms for each measurement.

Results:

• OK - The resistance is more than 20,000 Ohms for each measurement. Proceed to Test Step 3.

• Not OK - The resistance is less than 20,000 Ohms for each measurement.

  Repair: Repair the connectors or wiring and/or replace the connectors or wiring.

  STOP

Test Step 3. Check the Analog Sensor Supply Voltage at the Primary ECM.

1. Disconnect the primary ECM connector J1/P1.

2. Remove the wire 997-OR(Orange) from the primary ECM connector P1-36. Remove the wire 993-BR(Brown) from the primary ECM connector P1-30. Install wire jumpers into P1-36 and into P1-30.

   Note: If you remove the sensor common from the ECM, an open circuit diagnostic code will be generated for all sensors that use the sensor common. Troubleshoot the original code. Delete the logged diagnostic codes when you are finished.

3. Reconnect ECM connector J1/P1.

4. Turn the circuit breaker for the battery to the ON position.

5. Turn the ECS to the STOP position. The engine should be OFF.

6. Measure the voltage between the wire jumper in the analog supply P1-36 and the wire jumper in the analog return P1-30.

7. Turn the ECS to the OFF/RESET position.

8. Remove the wire jumpers. Replace the wires that were removed above. Reconnect ECM connector J1/P1.

Expected Result:

The supply voltage should be 5.0 ± 0.2 VDC.

Results:

• OK - The supply voltage is 5.0 ± 0.2 VDC. Proceed to Test Step 4.

• Not OK - The supply voltage is not 5.0 ± 0.2 VDC.

  Repair: Perform the diagnostic functional test Troubleshooting, "Electrical Power Suply".

  STOP

Test Step 4. Check the Analog Sensor Supply Voltage at the Sensor Connector.

1. Turn the ECS to the STOP position. The engine should be OFF.

2. Measure the voltage between socket-A and socket-B on the harness side of all analog sensor connectors.

3. Turn the ECS to the OFF/RESET position.

Expected Result:

The supply voltage should be 5.0 ± 0.2 VDC.

Results:

• OK - The supply voltage is 5.0 ± 0.2 VDC. Proceed to Test Step 5.

• Not OK - The supply voltage is not 5.0 ± 0.2 VDC.

  Repair: There is an open circuit in the harness or connectors. Repair the connectors or wiring and/or replace the connectors or wiring.

  STOP

Test Step 5. Check the Analog Sensors for Short Circuits.

1. Turn the ECS to the STOP position. The engine should be OFF.

2. Measure the voltage between socket-A and socket-B on the harness side of an analog sensor connector. Leave this sensor disconnected.

3. Connect one sensor at a time.

   Note: If the sensor is disconnected from the harness, an open circuit diagnostic code will be generated for that sensor. Troubleshoot the original diagnostic code. Delete the logged diagnostic codes when you are finished.

4. Repeat this step with all of the analog sensors. For the last sensor, move the voltmeter to another sensor connector. Check the last sensor, as described above.

5. Turn the ECS to the OFF/RESET position.

6. Reconnect all sensors.

Expected Result:

The supply voltage should be 5.0 ± 0.2 VDC after each analog sensor is connected.

Results:

• OK - The supply voltage is 5.0 ± 0.2 VDC after each analog sensor is connected.

  Repair: The problem may be intermittent. If the problem is intermittent, perform the diagnostic functional test Troubleshooting, "Inspecting Electrical Connectors".

  STOP

• Not OK - The voltage is okay before the sensor is connected. The voltage is not okay after the sensor is connected. The sensor may be internally shorted.

  Repair: Temporarily replace the sensor. Verify that the new sensor solves the problem before permanently installing the new sensor.

  STOP