C1.5 and C2.2 Engines for Caterpillar Built Machines Caterpillar

Sensor Signal (Analog, Passive) - Test

Usage:

This procedure covers the following diagnostic codes:

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Table 1
Diagnostic Trouble Codes for the Engine Temperature Sensors
J1939 Code	Description	Notes
110-3	Engine Coolant Temperature : Voltage Above Normal	The ECM detects the following conditions: The signal voltage from the engine coolant temperature sensor is greater than 4.85 VDC for at least 1 second. The engine has been running for at least 3 minutes. The warning lamp will flash. The engine will be derated. DPF regeneration will be disabled. The engine may show the following symptoms: Poor stability Poor cold running White smoke
110-4	Engine Coolant Temperature : Voltage Below Normal	The ECM detects the following conditions: The signal voltage from the engine coolant temperature sensor is less than 0.08 VDC for at least 1 second. The keyswitch has been ON for at least 2 seconds. The warning lamp will flash. The engine will be derated. DPF regeneration will be disabled. The engine may show the following symptoms: Poor stability Poor cold running White smoke
172-3	Engine Air Inlet Temperature : Voltage Above Normal	The ECM detects the following conditions: The signal voltage from the air intake temperature sensor is greater than 4.85 VDC for at least 0.5 seconds. The engine is running. The warning lamp will come on.
172-4	Engine Air Inlet Temperature : Voltage Below Normal	The ECM detects the following conditions: The signal voltage from the air intake temperature sensor is less than 0.08 VDC for at least 0.5 seconds. The engine is running. The warning lamp will come on.
3241-3	Exhaust Gas Temperature 1 : Voltage Above Normal	The ECM detects the following conditions: The signal voltage from the DPF outlet temperature sensor is greater than 5 VDC for at least 1 second. The keyswitch is on for at least 2 seconds. The coolant temperature is at least 70° C (158° F). The warning lamp will flash. The engine will be derated.
3241-4	Exhaust Gas Temperature 1 : Voltage Below Normal	The ECM detects the following conditions: The signal voltage from the DPF outlet temperature sensor is less than 0.05 VDC for at least 1 second. The keyswitch is on for at least 2 seconds. The warning lamp will flash. The engine will be derated.
3242-3	Aftertreatment #1 DPF Intake Gas Temperature : Voltage Above Normal	The ECM detects the following conditions: The signal voltage from the DPF intake temperature sensor is greater than 5 VDC for at least 1 second. The keyswitch is on for at least 2 seconds. The warning lamp will flash. The engine will be derated.
3242-4	Aftertreatment #1 DPF Intake Gas Temperature : Voltage Below Normal	The ECM detects the following conditions: The signal voltage from the DPF intake temperature sensor is less than 0.05 VDC for at least 1 second. The keyswitch is on for at least 2 seconds. The warning lamp will flash. The engine will be derated. DPF regeneration will be disabled.
4765-3	Aftertreatment #1 Diesel Oxidation Catalyst Intake Gas Temperature : Voltage Above Normal	The ECM detects the following conditions: The signal voltage from the Diesel Oxidation Catalyst (DOC) intake temperature sensor is greater than 5 VDC for at least 1 second. The keyswitch is ON for at least 2 seconds. The warning lamp will flash. The engine will be derated. DPF regeneration will be disabled.
4765-4	Aftertreatment #1 Diesel Oxidation Catalyst Intake Gas Temperature : Voltage Below Normal	The ECM detects the following conditions: The signal voltage from the DOC intake temperature sensor is less than 0.05 VDC for at least 1 second. The keyswitch is ON for at least 2 seconds. The warning lamp will flash. The engine will be derated. DPF regeneration will be disabled.
5487-3	Aftertreatment 1 Burner Unit Combustion Chamber Temperature : Voltage Above Normal	The ECM detects the following conditions: The signal voltage from the Aftertreatment Regeneration Device (ARD) combustion temperature sensor is greater than 5 VDC for at least 1 second. The keyswitch is ON for at least 2 seconds. The warning lamp will flash. The engine will be derated. DPF regeneration will be disabled.
5487-4	Aftertreatment 1 Burner Unit Combustion Chamber Temperature : Voltage Below Normal	The ECM detects the following conditions: The signal voltage from the ARD combustion temperature sensor is less than 0.05 VDC for at least 1 second. The keyswitch is ON for at least 2 seconds. The warning lamp will flash. The engine will be derated. DPF regeneration will be disabled.

This procedure covers open circuit diagnostic codes and short circuit diagnostic codes that are associated with the following sensors:

Coolant temperature sensor
Inlet air temperature sensor
DPF outlet temperature sensor
DPF intake temperature sensor
DOC intake temperature sensor
ARD combustion temperature sensor

The following background information is related to this procedure:

The troubleshooting procedures for the diagnostic codes of each temperature sensor are identical. The temperature sensors have two terminals. The signal line is connected to each sensor connector terminal 2. Terminal 1 is the return line. The signal voltage from terminal 1 of each sensor is supplied to the appropriate terminal in the P2/J2 connector or the P1/J1 connector.

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 at the connector indicates that the wires 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	g03693910
Schematic for the engine temperature sensors

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Illustration 2	g03694444
P2 pin locations for the temperature sensors (6) Coolant temperature sensor signal (7) Air intake temperature sensor signal (14) DPF intake temperature sensor signal (15) DOC intake temperature sensor signal (26) Coolant temperature sensor ground (27) Air intake temperature sensor ground (34) DPF intake temperature sensor ground (35) DOC intake temperature sensor ground (54) ARD combustion temperature sensor ground (55) DPF outlet temperature sensor ground (74) ARD combustion temperature sensor signal (75) DPF outlet temperature sensor signal

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Table 2
Troubleshooting Test Steps	Values	Results
1. Verify All Active Diagnostic Codes A. Connect the electronic service tool to the diagnostic connector. B. Turn the keyswitch to the ON position. Note: Wait at least 30 seconds for activation of the diagnostic codes. C. Use the electronic service tool in order to verify if any of the diagnostic codes that are listed in Table 1 are active or recently logged.	Diagnostic codes	Result: None of the diagnostic codes are active or recently logged. The fault may be intermittent. Refer to Troubleshooting, "Electrical Connectors - Inspect" in order to identify intermittent faults.
2. Inspect Electrical Connectors and Wiring A. Thoroughly inspect the terminal connections on the P2/J2 ECM connectors. B. Thoroughly inspect the connectors for the engine temperature sensors. C. Refer to Troubleshooting, "Electrical Connectors - Inspect". D. 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. E. Check the screw for the ECM connector for the correct torque of 6 N·m (53 lb in). F. Check the harness for abrasions and for pinch points from the sensors back to the ECM. G. Verify that the latch tab of the connector is correctly latched. Also verify that the latch tab of the connector has returned to the fully latching position.	Loose connection or damaged wire	Result: There is a fault in a connector or the wiring. Repair the connectors or the harness and/or replace the connectors or the harness. Ensure that all of the seals are correctly in place and ensure that the connectors are correctly connected. 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 connected and/or inserted and the harness is free of corrosion, of abrasion and of pinch points. Proceed to Test Step 3.
3. Verify The Type of Active Diagnostic Code A. Turn the keyswitch to the ON position. Wait at least 10 seconds for activation of the diagnostic codes. B. Access the "Active Diagnostic Code" screen on the electronic service tool and check for active diagnostic codes. C. Determine if the diagnostic code is related to an open circuit fault or a short circuit fault.	Diagnostic codes	Result: An XXXX-4 diagnostic code is active at this time. Proceed to Test Step 4. Result: An XXXX-3 diagnostic code is active at this time. Proceed to Test Step 6.
4. Disconnect The Sensor In Order To Create An Open Circuit A. Turn the keyswitch to the OFF position. B. Disconnect the sensor connector of the sensor with the XXXX-4 diagnostic code. C. Turn the keyswitch to the ON position. Note: Wait at least 10 seconds for activation of the diagnostic codes. D. Access the "Active Diagnostic Code" screen of the electronic service tool. Check for an active XXXX-3 diagnostic code.	Diagnostic codes	Result: An XXXX-3 diagnostic code became active after disconnecting the sensor. Inspect the seals of the connectors for damage. Refer to Troubleshooting, "Electrical Connectors - Inspect". Connect the sensor and verify that the XXXX-4 diagnostic code returns. If the diagnostic code returns, the sensor is faulty. Replace the sensor. Use the electronic service tool in order to clear all logged diagnostic codes and confirm that the fault has been eliminated. Result: The XXXX-4 diagnostic code is still active after disconnecting the sensor. Proceed to Test Step 5.
5. Create an Open Circuit at the ECM Connector A. Turn the keyswitch to the OFF position. B. Disconnect the P2 connector from the ECM. C. Thoroughly inspect the ECM connectors. Refer to Troubleshooting, "Electrical Connectors -Inspect". D. Turn the keyswitch to the ON position. Note: Wait at least 10 seconds for activation of the diagnostic codes. E. Access the "Active Diagnostic Code" screen of the electronic service tool. Check for an active XXXX-3 diagnostic code.	Diagnostic codes	Result: An XXXX-3 diagnostic code became active after disconnecting the P2 connector. The fault is in the wiring between the suspect sensor and the ECM. 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 XXXX-4 diagnostic code is still active with the P2 connector disconnected. Proceed to Test Step 8.
6. Create a Short Circuit at the Sensor Harness Connector A. Disconnect the suspect sensor connector. B. Fabricate a jumper wire 150 mm (6 inch) long. Crimp a terminal to both ends of the wire. C. Install the jumper wire between terminal 1 and terminal 2 on the harness connector for the suspect sensor. D. Turn the keyswitch to the ON position. E. Monitor the "Active Diagnostic Code" screen on the electronic service tool. Note: Wait at least 10 seconds for the activation of any diagnostic fault codes.	Diagnostic codes	Result: An XXXX-4 diagnostic code is active when the jumper is installed. Temporarily connect the suspect sensor. If the diagnostic code remains active, replace the sensor. Use the electronic service tool in order to clear all logged diagnostic codes and then verify that the repair eliminates the fault. Result: The XXXX-3 diagnostic code remains active with the jumper installed. Proceed to Test Step 7.
7. Check the Wiring for an Open Circuit A. Turn the keyswitch to the OFF position. B. Disconnect the P2 connector and the connector on the suspect sensor. C. Thoroughly inspect the ECM connectors. Refer to Troubleshooting, "Electrical Connectors -Inspect". D. Use a suitable multimeter to take the following resistance measurements: · The sensor signal wire from the sensor connector to the P2 connector · The sensor ground wire from the sensor connector to the P2 connector	Less than 5 Ohms	Result: At least one of the resistance measurements is greater than 5 Ohms. The fault is the wiring between the suspect sensor and the P2 connector. Replace the faulty wiring. Use the electronic service tool in order to clear all logged diagnostic codes. Result: All resistance measurements are less than 5 Ohms. Proceed to Test Step 8.
8. Check the ECM 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 replacement ECM, install a replacement ECM. Refer to Troubleshooting, "Replacing the ECM". D. Use the electronic service tool in order to clear all logged diagnostic codes.	ECM	Result: The fault is cleared with the replacement ECM. Reconnect the suspect ECM. If the fault returns with the suspect ECM, replace the 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.