C4.4 Marine Generator Set Caterpillar

Sensor Signal (Analog, Active) - Test

Usage:

C4.4 NRP

This procedure covers the following diagnostic codes:

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Table 1
Diagnostic Trouble Codes for Analog Active Sensors
J1939 Code	Code Description	Comments
94-3	Engine Fuel Delivery Pressure : Voltage Above Normal (If equipped)	The ECM detects the following conditions: The signal voltage from the secondary fuel filter inlet pressure sensor is above 4.8 VDC. If equipped, the warning light will come on. The ECM will log the diagnostic code.
94-4	Engine Fuel Delivery Pressure : Voltage Below Normal (If equipped)	The ECM detects the following conditions: The signal voltage from the secondary fuel filter inlet pressure sensor is less than 0.2 VDC. If equipped, the warning light will come on. The ECM will log the diagnostic code.
100-3	Engine Oil Pressure : Voltage Above Normal	The Electronic Control Module (ECM) detects the following conditions: The signal voltage from the engine oil pressure sensor is greater than 4.8 VDC for more than 8 seconds. If equipped, the warning lamp will come on. The ECM will log the diagnostic code. The ECM will set data for engine oil pressure to the default value. The default engine oil pressure is 600 kPa (87 psi). The electronic service tool will display "Voltage Above Normal" on the status screens.
100-4	Engine Oil Pressure : Voltage Below Normal	The ECM detects the following conditions: The signal voltage from the engine oil pressure sensor is less than 0.2 VDC for more than 8 seconds. The ECM has been powered for at least 2 seconds. If equipped, the warning lamp will come on. The ECM will log the diagnostic code. The ECM will set data for the engine oil pressure to the default value. The default engine oil pressure is 600 kPa (87 psi). The electronic service tool will display "Voltage Below Normal" on the status screens.
109-3	Engine Coolant Pressure : Voltage Above Normal (If equipped)	The Electronic Control Module (ECM) detects the following conditions: The signal voltage from the engine coolant pressure sensor is greater than 4.8 VDC. If equipped, the warning lamp will come on. The ECM will log the diagnostic code. The electronic service tool will display "Voltage Above Normal" on the status screens.
109-4	Engine Coolant Pressure : Voltage Below Normal (If equipped)	The ECM detects the following conditions: The signal voltage from the engine coolant pressure sensor is less than 0.2 VDC. If equipped, the warning lamp will come on. The ECM will log the diagnostic code. The electronic service tool will display "Voltage Below Normal" on the status screens.
157-3	Engine Injector Metering Rail #1 Pressure : Voltage Above Normal	The ECM detects the following conditions: The signal voltage for the fuel rail pressure sensor is more than 4.925 VDC for 0.6 seconds. If equipped, the warning lamp will flash. The ECM will log the diagnostic code. The electronic service tool will display "70000 kPa" next to "Desired Fuel Rail Pressure" and "Actual Fuel Rail Pressure" on the status screens. The engine will be derated.
157-4	Engine Injector Metering Rail #1 Pressure : Current Below Normal	The ECM detects the following conditions: The signal voltage for the fuel rail pressure sensor is less than 0.065 VDC for 0.6 seconds. If equipped, the warning lamp will flash. The ECM will log the diagnostic code. The electronic service tool will display "70000 kPa" next to "Desired Fuel Rail Pressure" and "Actual Fuel Rail Pressure" on the status screens. The engine will be derated.
1208-3	Engine Pre-filter Oil Pressure : Voltage Above Normal	The Electronic Control Module (ECM) detects the following conditions: The signal voltage from the engine pre-filter oil pressure sensor is greater than 4.8 VDC for more than 8 seconds. If equipped, the warning lamp will come on. The ECM will log the diagnostic code.
1208-4	Engine Pre-filter Oil Pressure : Voltage Below Normal	The ECM detects the following conditions: The signal voltage from the engine pre-filter oil pressure sensor is less than 0.2 VDC for more than 8 seconds. The ECM has been powered for at least 2 seconds. If equipped, the warning lamp will come on. The ECM will log the diagnostic code.
1381-3	Engine Fuel Supply Pump Inlet Pressure : Voltage Above Normal (If equipped)	The ECM detects the following conditions: The signal voltage from the primary fuel filter outlet pressure sensor is above 4.8 VDC. If equipped, the warning light will come on. The ECM will log the diagnostic code.
1381-4	Engine Fuel Supply Pump Inlet Pressure : Voltage Below Normal (If equipped)	The ECM detects the following conditions: The signal voltage from the primary fuel filter outlet pressure sensor is less than 0.2 VDC. If equipped, the warning light will come on. The ECM will log the diagnostic code.
2434-3	Engine Exhaust Manifold Bank #1 Temperature #1 : Voltage Above Normal	The Electronic Control Module (ECM) detects the following conditions: The signal voltage from the exhaust gas temperature sensor is greater than 4.8 VDC. If equipped, the warning lamp will come on. The ECM will log the diagnostic code. The electronic service tool will display "Voltage Above Normal" on the status screens.
2434-4	Engine Exhaust Manifold Bank #1 Temperature #1 : Voltage Below Normal	The ECM detects the following conditions: The signal voltage from the exhaust gas temperature sensor is less than 0.2 VDC. If equipped, the warning lamp will come on. The ECM will log the diagnostic code. The electronic service tool will display "Voltage Below Normal" on the status screens.
2435-3	Seawater Pump Outlet Pressure : Voltage Above Normal (If equipped)	Note: This code is only applicable to engines that use a raw water cooling system. The Electronic Control Module (ECM) detects the following conditions: The signal voltage from the seawater pump outlet pressure sensor is greater than 4.8 VDC. If equipped, the warning lamp will come on. The ECM will log the diagnostic code. The electronic service tool will display "Voltage Above Normal" on the status screens.
2435-4	Seawater Pump Outlet Pressure : Voltage Below Normal (If equipped)	Note: This code is only applicable to engines that use a raw water cooling system. The ECM detects the following conditions: The signal voltage from the seawater pump outlet pressure sensor is less than 0.2 VDC. If equipped, the warning lamp will come on. The ECM will log the diagnostic code. The electronic service tool will display "Voltage Below Normal" on the status screens.
3563-3	Engine Intake Manifold #1 Absolute Pressure : Voltage Above Normal	The ECM detects the following conditions: The signal voltage from the intake manifold pressure sensor is above 4.8 VDC for at least 8 seconds. The ECM has been powered for 2 seconds. If equipped, the warning light will come on. The ECM will log the diagnostic code. The data for the intake manifold pressure will be set to a maximum valid pressure for 2 seconds. The ECM will then flag the intake manifold pressure as being invalid. A default value is then used for the intake manifold pressure.
3563-4	Engine Intake Manifold #1 Absolute Pressure : Voltage Below Normal	The ECM detects the following conditions: The signal voltage from the intake manifold pressure sensor is less than 0.2 VDC for at least 8 seconds. The ECM has been powered for 2 seconds. If equipped, the warning light will come on. The ECM will log the diagnostic code. The data for the intake manifold pressure will be set to a maximum valid pressure for 2 seconds. The ECM will then flag the intake manifold pressure as being invalid. A default value is then used for intake manifold pressure.
5417-3	Fuel Filter (Suction Side) Intake Pressure : Voltage Above Normal (If equipped)	The ECM detects the following conditions: The signal voltage from the primary fuel filter inlet pressure sensor is above 4.8 VDC. If equipped, the warning light will come on. The ECM will log the diagnostic code.
5417-4	Fuel Filter (Suction Side) Intake Pressure : Voltage Below Normal (If equipped)	The ECM detects the following conditions: The signal voltage from the primary fuel filter inlet pressure sensor is less than 0.2 VDC. If equipped, the warning light will come on. The ECM will log the diagnostic code.
5579-3	Engine Filtered Fuel Delivery Pressure : Voltage Above Normal	The ECM detects the following conditions: The signal voltage from the secondary fuel filter outlet pressure sensor is above 4.8 VDC. If equipped, the warning light will come on. The ECM will log the diagnostic code.
5579-4	Engine Filtered Fuel Delivery Pressure : Voltage Below Normal	The ECM detects the following conditions: The signal voltage from the secondary fuel filter outlet pressure sensor is less than 0.2 VDC. If equipped, the warning light will come on. The ECM will log the diagnostic code.
Follow the troubleshooting procedure in order to identify the root cause of the fault.

The following conditions must exist before any of the above codes will become active:

There are no active 3509 codes.
There are no active 3510 codes.
There are no active 168 codes.

The following background information is related to this procedure:

Note: The terminals on the fuel rail pressure sensor are wired differently from all other pressure sensors.

The 5 VDC sensor supply provides power to all 5 VDC sensors. The ECM supplies 5 VDC to terminal "3" of the fuel rail pressure sensor connector. The ECM supplies 8 VDC to terminal "A" of the exhaust gas temperature sensor connector. The ECM supplies 5 VDC to terminal "1" of all other active sensor connectors. The sensor common from the ECM connector goes to terminal "1" of the connector for the fuel rail pressure sensor. The sensor common from the ECM connector goes to terminal "B" of the connector for the exhaust gas temperature sensor. The sensor common from the ECM connector goes to terminal "2" of all other active sensor connectors. The sensor supply is output short circuit protected. A short circuit to the battery will not damage the circuit inside the ECM.

Pull-up Voltage

The 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, an open circuit diagnostic code (XXXX-3) is generated for the sensor.

If the sensor is disconnected, pull-up voltage indicates that the wires from the sensor connector to the ECM 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.

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Illustration 1	g03598889
Schematic for the active sensors on the P1 connector

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Illustration 2	g03598885
Schematic for the active sensors on the P2 connector

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Illustration 3	g03600796
Pin locations on the P1 connector for the active sensors (2) Sensor power (3) Sensor return (15) Secondary pre-filter pressure sensor signal (25) Primary pre-filter pressure sensor signal (26) Primary post-filter pressure sensor signal (47) Secondary post-filter pressure sensor signal

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Illustration 4	g03600816
Pin locations on the P2 connector for the active sensors (4) IMAP pressure sensor signal (5) Sea water pressure sensor signal (15) Engine oil pre-filter pressure sensor signal (18) Exhaust gas temperature sensor signal (34) Coolant pressure sensor signal (35) Engine oil post-filter pressure sensor signal (36) Exhaust gas temperature sensor return (37) Fuel rail pressure sensor signal (44) Exhaust gas temperature sensor power (46) Sensor power (47) Sensor return (56) Sensor power (57) Sensor return

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Illustration 5	g03374231
Fuel rail pressure sensor (1) Ground (2) Signal (3) 5 VDC Supply

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Illustration 6	g01170310
Typical example of an engine pressure sensor (1) 5 VDC Supply (2) Ground (3) Signal

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Illustration 7	g03601176
Exhaust Gas Temperature Sensor (if equipped) (A) 5 VDC Supply (B) Ground (C) Signal

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Table 2
Troubleshooting Test Steps	Values	Results
1. Inspect Electrical Connectors and Wiring A. Thoroughly inspect the terminal connections on the P2/J2 ECM connectors and the engine active sensors. Refer to Troubleshooting, "Electrical Connectors - Inspect". B. Perform a 45 N (10 lb) pull test on each of the wires in the ECM connector and the sensor connectors that are associated with the active diagnostic code. C. Check the screw for the ECM connector for the correct torque of 6 N·m (53 lb in). D. Check the harness for corrosion, abrasion, and pinch points from the engine active sensors to the ECM.	Loose connection or damaged wire	Result: There is a fault in a connector or the wiring. Repair any faulty connectors or replace the wiring harness. Ensure that all of the seals are properly in place and ensure that the connectors are correctly coupled. Use the electronic service tool to clear all logged diagnostic codes and verify that the repair eliminates the fault. Result: All connectors, pins, and sockets are correctly coupled and/or inserted. The harness is free of corrosion, abrasion, and pinch points. Proceed to Test Step 2.
2. Check For Active Diagnostic Codes A. Turn the isolator switch to the OFF position. B. Connect the electronic service tool to the diagnostic connector. C. Turn the isolator switch to the ON position. Wait at least 10 seconds for activation of the diagnostic codes. D. Verify if any of the diagnostic codes that are listed in Table 1 are active. E. Turn the isolator switch to the OFF position.	Diagnostic codes	Result: There are no active diagnostic codes for the active sensors. If there are logged diagnostic codes for the active sensors, the fault may be intermittent. Refer to Troubleshooting, "Electrical Connectors - Inspect" in order to identify intermittent faults. Result: An XXXX-3 or an XXXX-4 diagnostic code is active for one or more of the active sensors. Proceed to Test Step 3.
3. Check the Supply Voltage at the Sensor Connector A. Turn the isolator switch to the OFF position. B. Disconnect the connector for the suspect sensor. C. Turn the isolator switch to the ON position. Do not start the engine. D. Measure the voltage between the supply terminal and the ground terminal on the harness connector for the suspect sensor. The voltage measurement should be 8.0 ± 0.2 VDC for the exhaust gas temperature sensor. The voltage measurement should be 5.0 ± 0.2 VDC for all other sensors. E. Turn the isolator switch to the OFF position. F. Reconnect the sensor.	7.8 VDC to 8.2 VDC for the exhaust gas temperature sensor. 4.8 VDC to 5.2 VDC for all other sensors.	Result: The voltage measurement is not within the expected range. The fault is in the supply wire or the ground wire in the engine wiring harness. Repair the faulty wiring or replace the faulty wiring. Use the electronic service tool to clear all logged diagnostic codes. Return the engine to service. Result: The voltage measurement is within the expected range - The correct supply voltage is reaching the sensor. Proceed to Test Step 4.
4. Check the Type of Diagnostic Code that is Active A. Turn the isolator switch to the ON position. Wait at least 10 seconds for activation of the diagnostic codes. B. Use the electronic service tool to check for active diagnostic codes. Record all active diagnostic codes.	Diagnostic codes	Result: An XXXX-4 diagnostic code is active for one or more of the active sensors at this time. Proceed to Test Step 5. Result: An XXXX-3 diagnostic code is active for one or more of the active sensors at this time. Proceed to Test Step 7.
5. Create An Open Circuit at the Sensor Connector A. Turn the isolator switch to the OFF position. B. Disconnect the connector for the sensor with the XXXX-4 diagnostic code. C. Turn the isolator switch to the ON position. Wait for at least 10 seconds for activation of the diagnostic codes. D. Use the electronic service tool to check the "Active Diagnostic Code" screen. Check for an XXXX-3 diagnostic code.	Diagnostic codes	Result: An XXXX-4 diagnostic code was active before disconnecting the sensor. An XXXX-3 diagnostic code became active after disconnecting the sensor - the sensor is faulty. Temporarily connect a new sensor to the harness, but do not install the new sensor in the engine. Use the electronic service tool in order to verify that the repair eliminates the fault and then permanently install the new sensor. Use the electronic service tool to clear all logged diagnostic codes and verify that the repair eliminates the fault. Result: The XXXX-4 diagnostic code is still active. Proceed to Test Step 6.
6. Check the Signal Wire for a Short Circuit A. Turn the isolator switch to the OFF position. B. Disconnect the P2 connector and disconnect the connector from the suspect sensor. C. Use a multimeter to check for resistance between the applicable signal terminal on the P2 connector and all other terminals on the P2 connector. Refer to Illustration 5.	Greater than 100 Ohms	Result: At least one of the resistance measurements is less than 100 Ohms - The fault is in the engine harness. Repair the faulty connector or replace the faulty harness. Use the electronic service tool to verify that the repair eliminates the fault. Result: All resistance measurements are greater than 100 Ohms. Proceed to Test Step 9.
7. Create a Short Circuit at the Sensor Connector A. Turn the isolator switch to the OFF position. B. Disconnect the connector for the suspect sensor. C. Fabricate a jumper wire that is 150 mm (6 inch) long. Crimp a terminal to both ends of the wire. D. Use the jumper to connect the sensor signal terminal to the sensor ground terminal on the harness connector for the suspect sensor. E. Turn the isolator switch to the ON position. Do not start the engine. F. Access the "Active Diagnostic Codes" screen on the electronic service tool and check for an active XXXX-4 diagnostic code for the suspect sensor. G. Remove the jumper. Reconnect the sensor.	Diagnostic codes	Result: An XXXX-3 diagnostic code was active before installing the jumper. An XXXX-4 diagnostic code became active with the jumper installed - the sensor may be faulty. Temporarily connect a new sensor to the harness, but do not install the new sensor in the engine. Use the electronic service tool in order to verify that the repair eliminates the fault and then permanently install the new sensor. Use the electronic service tool in order to clear all logged diagnostic codes and verify that the repair eliminates the fault. Result: The XXXX-3 diagnostic code remains active when the jumper is installed. Proceed to Test Step 8.
8. Check the Signal Wire for an Open Circuit A. Turn the isolator switch to the OFF position. B. Disconnect the P2 connector and disconnect the connector from the suspect sensor. C. Use a multimeter to check for resistance between the applicable signal terminal on the sensor connector and the applicable terminal on the P2 connector. Refer to Illustration 2.	Less than two Ohms.	Result: The resistance measurement is greater than two Ohms - The fault is in the engine harness. Repair the faulty wiring or replace the faulty wiring. Use the electronic service tool to clear all logged diagnostic codes and verify that the repair eliminates the fault. Result: The resistance measurement is less than two Ohms. The fault is in the ECM. Proceed to Test Step 9.
9. Check if a Replacement ECM Eliminates the Fault A. Make sure that the latest flash file for the application is installed in the ECM. Refer to Troubleshooting, "Flash Programming". B. Contact the Technical Communicator at a Cat dealer. Note: This consultation can greatly reduce the repair time. C. If the Technical Communicator recommends the use of a test ECM, install a test ECM. Refer to Troubleshooting, "Replacing the ECM". D. Turn the isolator switch to the ON position. Use the electronic service tool to verify that the repair eliminates the fault.	Fault eliminated	Result: The fault is eliminated with the test ECM. Reconnect the suspect ECM. If the fault returns with the suspect ECM, permanently install the replacement ECM. Result: The fault is still present with the replacement ECM. Do not use the replacement ECM. Contact the Technical Communicator at a Cat dealer.