G3306B Petroleum Generator Set Engines Caterpillar

Sensor Signal (Analog, Active) - Test

Usage:

Use this procedure to troubleshoot the electrical system if a problem is suspected with the circuit for one of the analog sensors. Also, use this procedure if one of the diagnostic codes in Table 1 is active or easily repeated.

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Table 1
Diagnostic Codes Table
Description	Conditions which Generate this Code	System Response
100-3 Engine Oil Pressure Sensor : Voltage Above Normal	The Electronic Control Module (ECM) has detected a voltage on the signal wire of the sensor that is greater than 4.95 V for ten seconds.	The code is logged. The amber warning lamp is illuminated. The service tool displays "Error Indicator" on the status screen for this parameter.
100-4 Engine Oil Pressure Sensor : Voltage Below Normal	The ECM has detected a voltage on the signal wire of the sensor that is less than 0.2 V for ten seconds.
3563-3 Engine Intake Manifold #1 Absolute Pressure : Voltage Above Normal	The ECM has detected a voltage on the signal wire of the sensor that is greater than 4.95 V for five seconds.	The code is logged. The amber warning lamp is activated. The service tool displays "Error Indicator" on the status screen for this parameter.
3563-4 Engine Intake Manifold #1 Absolute Pressure : Voltage Below Normal	The ECM has detected a voltage on the signal wire of the sensor that is less than 0.2 V for five seconds.
4289-3 Aftertreatment #1 Three Way Catalytic Converter Intake Gas Temperature : Voltage Above Normal	The ECM has detected a voltage on the signal wire of the sensor that is greater than 4.8 V for five seconds.	The code is logged. The amber warning lamp is activated. The service tool displays "Error Indicator" on the status screen for this parameter.
4289-4 Aftertreatment #1 Three Way Catalytic Converter Intake Gas Temperature : Voltage Below Normal	The ECM has detected a voltage on the signal wire of the sensor that is less than 0.2 V for five seconds.
4290-3 Aftertreatment #1 Three Way Catalytic Converter Outlet Gas Temperature : Voltage Above Normal	The ECM has detected a voltage on the signal wire of the sensor that is greater than 4.8 V for five seconds.	The code is logged. The amber warning lamp is activated. The service tool displays "Error Indicator" on the status screen for this parameter.
4290-4 Aftertreatment #1 Three Way Catalytic Converter Outlet Gas Temperature : Voltage Below Normal	The ECM has detected a voltage on the signal wire of the sensor that is less than 0.2 V for five seconds.

The following analog sensors are used by this engine:

Engine oil pressure sensor
Intake manifold pressure sensor
Temperature sensor at the inlet of the catalytic converter
Temperature sensor at the outlet of the catalytic converter

Background Information

The ECM continuously creates a pull-up voltage on the signal wire for each sensor. The ECM uses this pull-up voltage in order to detect a problem in the signal circuit. When the ECM detects voltage that is above a threshold on the signal wire, the ECM activates a high voltage -3 diagnostic code. When the ECM detects voltage that is below a threshold on the signal wire, the ECM activates a low voltage -4 diagnostic code.

Note: There may be a delay of 30 seconds for Caterpillar Electronic Technician (ET) to display an active diagnostic code. When you check for a diagnostic code, be sure to wait at least 30 seconds.

The following components can cause these codes:

Electrical connector or wiring
Sensor
ECM

The most likely cause of a code is a problem with an electrical connector or wiring. The least likely cause of a code is the ECM.

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Illustration 1	g01960470
Schematic for the analog sensors

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Illustration 2	g01960583
Locations of the sensors that are associated with the analog signal (left side engine view) (1) Intake manifold pressure sensor

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Illustration 3	g03431228
Locations of the sensors that are associated with the analog signal (right side engine view) (2) Engine oil pressure sensor

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Illustration 4	g02471238
Locations of the analog sensors that are for the catalytic converter/muffler (3) Temperature sensor for the inlet of the catalytic converter/muffler (4) Temperature sensor for the outlet of the catalytic converter/muffler

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Illustration 5	g01960607
Locations of the connectors at the ECM for the analog sensors (5) Connector for the sensors at the catalytic converter (6) J2/P2 ECM connectors (7) J1/P1 ECM connectors

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Illustration 6	g01960613
Terminal locations at the P1 ECM connector for the analog sensors (P1-24) Temperature at the outlet of the catalytic converter (P1-34) Analog return (P1-41) Analog sensor supply (P1-42) Analog sensor supply (P1-54) Temperature at the inlet of the catalytic converter (P1-55) Intake manifold pressure

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Illustration 7	g01960623
Terminal locations at the P2 ECM connector for the analog sensors (P2-37) Analog return (P2-38) Analog return (P2-45) Analog return (P2-46) Analog sensor supply (P2-47) Analog sensor supply (P2-56) Engine oil pressure

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Illustration 8	g02039134
Terminal locations at the harness connector for the analog sensors at the catalytic converter (Terminal A) Analog sensor supply (Terminal B) Analog return (Terminal C) Temperature sensor at the inlet of the catalytic converter (Terminal D) Analog sensor supply (Terminal E) Analog return (Terminal F) Temperature sensor at the outlet of the catalytic converter

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Illustration 9	g01240891
Terminal locations at the harness connector for the analog pressure sensors (Terminal 1) Analog sensor supply (Terminal 2) Analog return (Terminal 3) Signal

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Illustration 10	g01960628
Terminal locations at the harness connector for the analog temperature sensors (Terminal 1) Analog sensor supply (Terminal 2) Analog return (Terminal 3) Signal

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Table 2
Troubleshooting Test Steps	Values	Results
1. Determine if the Code is Logged or Active A. Turn the engine control switch to the OFF position. Remove electrical power from the engine. B. Connect Cat ET to the service tool connector. C. Restore electrical power to the engine. Turn the engine control switch to the STOP position. D. Monitor the active diagnostic code and the logged diagnostic codes on Cat ET. Wait at least 30 seconds in order for diagnostic codes to become active. E. Turn the engine control switch to the OFF position. Remove electrical power from the engine. F. Identify the diagnostic code.	Diagnostic code	Result: There is not an active code for one of the analog sensors. Do not troubleshoot a logged code unless the code relates to an operator complaint. If the code is logged and the code does not relate to an operator complaint, clear the code. If the code is logged and the code relates to an operator complaint, proceed to Test Step 2. Result: There is an active code for one of the analog sensors. Proceed to Test Step 3.

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Table 3
Troubleshooting Test Steps	Values	Results
2. Check the Integrity of the Connections at the Connectors A. Restore electrical power to the engine. Turn the engine control switch to the STOP position. B. Install a 7X-1708 Multimeter Probe (RED) and a 7X-1709 Multimeter Probe (BLACK) onto the test leads of a multimeter. Ensure that the multimeter probes are in good repair. Bent probes may contact other terminals inside the connector. C. Check for an intermittent problem at the ECM connector. Do not disconnect any harness connectors in order to perform this procedure. D. Carefully install the spoons (multimeter probes) into the terminal locations for the appropriate sensor supply and the analog return at the ECM connector. E. While you observe the voltage reading on the multimeter, wiggle the wires, and pull on the wires at the connector for the suspect sensor. The voltage reading will not vary more than 0.5 V for a solid electrical connection. F. Remove the spoons (multimeter probes) from the connector. G. Check for an intermittent problem at the connector for the suspect sensor. Do not disconnect any harness connectors in order to perform this procedure. H. Carefully install the spoons (multimeter probes) into the terminal locations for the sensor supply and the analog return. Install the spoons on the sensor side of the connector for the suspect sensor. I. Perform a manual wiggle test on the circuit . While you observe the voltage reading on the multimeter, wiggle the wires for the supply and the return at the ECM connector. The voltage reading will not vary more than 0.5 V for a solid electrical connection. J. Remove the spoons (multimeter probes) from the connector. K. Remove the electrical power from the ECM.	Connections	Result: The voltage reading did not vary more than 0.5 V. The connections are OK at the connectors. There does not appear to be an intermittent problem in the circuit at this time. Return the engine to service. Result: The voltage reading varied more than 0.5 V during the test. Disconnect the suspect connector and inspect the connector and the terminals for moisture, damage, and corrosion. Repair the connectors and/or the terminals. Return the engine to service.

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Table 4
Troubleshooting Test Steps	Values	Results
3. Check the Supply Voltage at the Sensor Connector A. Disconnect the harness connector for the suspect sensor. B. Measure the voltage between the terminals for the sensor supply and the analog return at the harness connector for the suspect sensor.	Voltage	Result: The voltage is between 4.5 VDC and 5.5 VDC. The supply voltage is reaching the sensor connector. Record the voltage measurement. If you are troubleshooting a -3 diagnostic code, proceed to Test Step 5. If you are troubleshooting a -4 diagnostic code, proceed to Test Step 8. Result: The voltage is less than 4.5 VDC or the voltage is greater than 5.5 VDC. The supply voltage at the sensor connector is incorrect. There appears to be a problem in the wiring harness or in a connector. There may be a problem with the power supply at the ECM. Proceed to Test Step 4.
4. Measure the Sensor Supply Voltage at the ECM A. Disconnect the appropriate ECM connector that is for the affected sensor supply. B. Fabricate two jumper wires that are long enough to be used to create test circuits at the ECM connector. Crimp connector sockets to one end of each of the jumper wires. C. Remove the wires from the terminal locations for the appropriate sensor supply and the analog return. Install a jumper wire into each of these terminal locations. D. Connect the J1/P1 ECM connector. E. Restore the electrical power to the engine. Set the engine control switch to the STOP position. F. Measure the voltage between the jumper wires for the appropriate sensor supply and the analog return. G. Remove the electrical power from the engine. Set the engine control switch to the OFF position. H. Restore the wiring to the original configuration.	Voltage	Result: The supply voltage between the jumper wires at the ECM is between 4.5 VDC and 5.5 VDC. The ECM is OK. There is a problem in the harness or in a connector. Repair the wiring harness. Verify that the repair resolved the original problem. Result: The supply voltage between the jumper wires at the ECM is not between 4.5 VDC and 5.5 VDC. Temporarily install a new ECM. Refer to Troubleshooting, "ECM - Replace". If the problem is resolved with the new ECM, install the original ECM and verify that the problem returns. If the new ECM operates correctly and the original ECM does not operate correctly, replace the original ECM. Verify that the repair resolved the original problem.

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Table 5
Troubleshooting Test Steps	Values	Results
5. Check for Battery Voltage on the Signal Wire A. Measure the voltage between the terminals for the sensor signal and the analog return on the harness connector for the suspect sensor.	Voltage	Result: The voltage measurement is less than the +Battery voltage. The signal wire is not shorted to the +Battery. Proceed to Test Step 6. Result: The voltage measurement is equal to the +Battery voltage. The signal wire is shorted to the +Battery. Repair the wiring, when possible. Replace parts, if necessary. Verify that the problem is resolved.
6. Check the Signal Wire for an Open Circuit A. Disconnect the sensor that is applicable to the diagnostic code. B. Connect a jumper wire between the signal terminal and the return terminal on the harness connector for the suspect sensor. The jumper wire will replace the sensor with a short circuit. C. Check that the -3 diagnostic code becomes a -4 diagnostic code with the jumper wire in place.	Diagnostic code	Result: The -3 code does not change to a -4 code when the jumper wire is connected. Connect the sensor. There is a problem with the wiring harness or with the ECM. Proceed to Test Step 7. Result: The -3 code changes to a -4 code when the jumper wire is connected. The wiring harness and the ECM are OK. Perform the following procedure: 1. Remove the jumper wire. 2. Connect a new sensor to the engine harness. Do not install the sensor into the engine. 3. Verify that the active -3 diagnostic code does not recur. 4. Install the sensor into the engine. 5. Clear all logged diagnostic codes and return the engine to service.

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Table 6
Troubleshooting Test Steps	Values	Results
7. Check the ECM for Proper Operation A. Fabricate a jumper wire that is long enough to create a test circuit across the ECM connector. Crimp connector sockets to each end of the jumper wire. B. Determine the terminal location at the appropriate ECM connector for the signal wire and the return wire of the suspect sensor. C. Remove the signal terminal and the return terminal from the ECM connector. D. Install the jumper wire between the terminal locations for the signal and the return at the ECM connector. The jumper wire will effectively replace the engine wiring with a short circuit. E. Use Cat ET to check for a -4 diagnostic code.	-4 code	Result: A -4 code is active when the jumper wire is installed. The ECM detected the jumper wire at the ECM connector. However, the ECM did not detect the jumper wire at the harness connector for the sensor. There is an open circuit in the wiring harness. Repair the wiring harness, when possible. Replace parts, if necessary. Verify that the problem is resolved. Result: A -4 code is not active when the jumper wire is installed. There is a problem with the ECM. Temporarily install a new ECM. Refer to Troubleshooting, "ECM - Replace". If the problem is resolved with the new ECM, install the original ECM and verify that the problem returns. If the new ECM operates correctly and the original ECM does not operate correctly, replace the original ECM.
8. Check the Signal Wire for a Short Circuit A. Disconnect the connector for the suspect sensor with the -4 diagnostic code. B. Use Cat ET to check that a -3 diagnostic code becomes active. C. Connect the sensor and check that the -4 diagnostic code recurs.	Diagnostic code	Result: When the sensor is disconnected, the -4 code remains active. The short circuit is in the wiring harness. There may be a problem with the ECM. Proceed to Test Step 9. Result: When the sensor is disconnected, the -4 code changes to a -3 code. The harness and the ECM are OK. There is a problem with the sensor. Perform the following procedure: 1. Connect a new sensor to the engine harness. Do not install the sensor into the engine. 2. Verify that the active -4 diagnostic code does not recur. 3. Install the sensor into the engine. 4. Clear all logged diagnostic codes and return the engine to service.

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Table 7
Troubleshooting Test Steps	Values	Results
9. Check the ECM for Proper Operation A. Determine the terminal location at the appropriate ECM connector for the signal wire of the suspect sensor. B. Remove the signal wire from the ECM connector. C. Check if the -4 diagnostic code becomes an active -3 active code.	Diagnostic code	Result: A -3 code becomes active when the signal wire is removed from the ECM connector. The ECM detected the open circuit at the ECM connector. However, the ECM did not detect the open circuit at the harness connector for the sensor. There is a problem with the wiring between the ECM connector and the harness connector for the sensor. There may be a problem with a connector. Repair the wiring or the connector, when possible. Replace parts, if necessary. Verify that the problem is resolved. Repair the wiring harness, when possible. Replace parts, if necessary. Verify that the problem is resolved. Result: A -3 code is not active when the signal wire is disconnected from the ECM connector. The ECM did not detect the open circuit at the ECM connector. There is a problem with the ECM. The ECM does not detect the open circuit at the ECM connector. There is a problem with the ECM. Temporarily install a new ECM. Refer to Troubleshooting, "ECM - Replace". If the problem is resolved with the new ECM, install the original ECM and verify that the problem returns. If the new ECM operates correctly and the original ECM does not operate correctly, replace the original ECM.