C9.3 Marine Auxiliary and Generator Set Engine Caterpillar

Sensor Signal (Analog, Passive) - Test

Usage:

C9.3 C93

Use this procedure to troubleshoot the electrical system if a problem is suspected with a sensor. Use this procedure if any one of the diagnostic codes in Table 1 is active or easily repeated.

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Table 1
Diagnostic Codes Table
J1939 Code and Description	Comments
105-3 Engine Intake Manifold #1 Temperature : Voltage Above Normal	The Electronic Control Module (ECM) detects the following conditions: The signal voltage from the intake manifold air temperature sensor is greater than 4.95 VDC for more than 8 seconds. Engine coolant temperature is above −10 °C (15.0 °F). The ECM will use the default value of 70 °C (158 °F) for the intake manifold air temperature. "Voltage High" will be displayed next to the status for "Intake Manifold Air Temperature" on the electronic service tool. The engine may show the following symptoms: Poor stability, Poor cold running, Poor acceleration under load, White smoke
105-4 Engine Intake Manifold #1 Temperature : Voltage Below Normal	The ECM detects the following conditions: The signal voltage from the intake manifold air temperature sensor is less than 0.2 VDC for more than 8 seconds. The ECM will use the default value of 70°C (158°F) for the intake manifold air temperature. "Voltage Low" will be displayed next to the status for "Intake Manifold Air Temperature" on the electronic service tool. The engine may show the following symptoms: Poor stability Poor cold running, Poor acceleration under load, White smoke.
110-3 Engine Coolant Temperature Sensor : Voltage Above Normal	The code is logged if the engine has been running for more than 7 minutes and an open circuit has been detected.
110-4 Engine Coolant Temperature Sensor : Voltage Below Normal	The code is logged. The ECM detects voltage that is not in the acceptable range.
172-3 Air Inlet Temperature Sensor : Voltage Above Normal	The code is logged. The ECM detects voltage that is not in the acceptable range.
172-4 Air Inlet Temperature Sensor : Voltage Below Normal	The code is logged. The ECM detects voltage that is not in the acceptable range.
174-3 Fuel Temperature Sensor : Voltage Above Normal	The code is logged. The ECM will flag the fuel temperature as invalid data and the fuel temperature is set to a default value of 40 °C (104 °F).
174-4 Fuel Temperature Sensor : Voltage Below Normal
175-3 Engine Oil Temperature Sensor:Voltage Above Normal	The code is logged. The ECM detects voltage that is not in the acceptable range.
175-4 Engine Oil Temperature Sensor:Voltage Below Normal	The code is logged. The ECM detects voltage that is not in the acceptable range.
441–3 Auxiliary Temperature #1 : Voltage Above Normal	The ECM detects the following conditions: The signal voltage from the hydraulic oil temperature sensor is greater than 4.975 VDC for more than 8 seconds.
441–4 Auxiliary Temperature #1 : Voltage Below Normal	The ECM detects the following conditions: The signal voltage from the hydraulic oil temperature sensor is less than 0.2 VDC for more than 8 seconds.

System Overview

The sensor signal for the passive sensor is routed from the ECM to terminal 1 of each sensor connector. The sensor return for the passive sensors is routed to the ECM from terminal 2 of each sensor connector.

Diagnostics on the Caterpillar Electronic Technician (ET)

Wiggle Test - The Wiggle Test allows you to monitor the status of the signals from the sensors.

For additional information regarding the Wiggle Test, refer to the documentation that accompanies the Cat ET software.

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Illustration 1	g01155187
Terminal locations at the connector for the passive analog sensors (Terminal 1) Sensor signal (Terminal 2) Analog sensor return

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Illustration 2	g06206642

Complete the procedure in the order in which the steps are listed.

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Table 2
Troubleshooting Test Steps	Values	Results
1. Check for Diagnostic Trouble Codes A. Connect to Caterpillar^® Electronic Technician (Cat ET). B. Turn the keyswitch to the ON position. C. Access the "Active Diagnostic Code" screen on Cat ET. Wait at least 30 seconds in order for the diagnostic codes to become active. D. Look for these active codes or logged codes: 1. -3 2. -4	Codes	Result: A -3 diagnostic code is active. Proceed to Test Step 2. Result: A -4 diagnostic code is active. Proceed to Test Step 3. Result: For a diagnostic code that is logged but not currently active, Proceed to Test Step 4.
2. Create a Short at the Sensor Connector A. Turn the keyswitch to the OFF position. B. Disconnect the suspect sensor. C. Install the jumper wire between terminal 1 (sensor signal) and terminal 2 (sensor return) at the sensor connector. D. Turn the keyswitch to the ON position. E. Monitor the diagnostic codes on Cat ET. Check for an active -4 diagnostic code for the suspect sensor. Wait at least 30 seconds in order for the diagnostic codes to become active. F. Turn the keyswitch to the OFF position.	Short Circuit Recognized	Result: The -3 diagnostic code remains active for the suspect sensor. Repair: There is an open in the harness. Repair the wiring or replace the harness. Verify that the problem is resolved. Result: A -4 diagnostic code became active after creating the short at the sensor connector. Repair: The wiring is OK. Replace the sensor. Verify that the problem is resolved.
3. Create an Open at the Suspect Sensor Connector A. Turn the keyswitch to the OFF position. B. Disconnect the sensor connector of the suspect sensor with the active -4 diagnostic code. C. Turn the keyswitch to the ON position. D. Monitor the diagnostic codes on Cat ET. Check for an active -3 diagnostic code for the suspect sensor. · For a 110-3 code, start the engine and let the engine idle for 7 minutes. The engine must be running for at least 7 minutes in order for the diagnostic to run. E. Turn the keyswitch to the OFF position.	Open Circuit Recognized	Result: The -4 diagnostic code remains active for the suspect sensor. Repair: There is an open in the harness. Repair the wiring or replace the harness. Verify that the problem is resolved. Result: A -3 diagnostic code became active after disconnecting the sensor. Repair: The wiring is OK. Replace the sensor. Verify that the problem is resolved.
4. Perform the Wiggle Test Carefully following this procedure is the best way to identify the root cause of an intermittent problem. A. Turn the keyswitch to the ON position. B. Use Cat ET to run the "Wiggle Test". C. Slowly wiggle the wiring and the connectors between the P2 connector and the sensor. Slowly wiggle the wiring and the connectors between the P1 connector and the sensor. Pay particular attention to the wiring near each connector. Be sure to wiggle all of the wiring. D. As you wiggle the wiring look for these problems. 1. Loose connectors or damaged connectors 2. Moisture on the connectors or the wiring 3. Damage that is caused by excessive heat 4. Damage that is caused by chafing 5. Improper routing of wiring 6. Damaged insulation	Wiggle test	Result: The wiring failed the Wiggle Test. Repair: There is a problem with the wiring. Repair the wiring or replace the wiring. Verify that the problem is resolved. Result: The wiring passed the Wiggle Test. Repair: The problem may be intermittent. Inspect the wiring. Refer to Troubleshooting, "Electrical Connectors - Inspect". If the wiring looks OK perform the following procedure. 1. Turn the keyswitch to the OFF position. 2. Disconnect the connectors. Carefully inspect the terminals for proper installation. Make sure that each terminal is clean and dry. 3. Insert a pin into each socket. Verify that each socket grips the pin firmly. Repair any problems. 4. Connect all connectors. 5. Verify that the problem is resolved. 6. Return the unit to service.

If the procedure did not correct the issue, contact your Cat dealer Technical Communicator (TC). For further assistance, your TC can confer with the Deal Solutions Network (DSN).