Selective Catalytic Reduction Retrofit Aftertreatment Caterpillar

Sensor Signal (Analog, Active) - Test

Usage:

SCR EF5

Use this procedure to troubleshoot a problem with a sensor. Also, use this procedure if one of the following diagnostic codes is active or easily repeated.

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Table 1
J1939 Code and Description	CDL Code and Description	Comments
4335-3 Aftertreatment #1 SCR Dosing Air Assist Absolute Pressure : Voltage Above Normal	3092-3 Aftertreatment #1 SCR Dosing Air Assist Pressure Sensor : Voltage Above Normal	The Electronic Control Module (ECM) detects signal voltage that is not in the acceptable range. The code is logged.
4335-4 Aftertreatment #1 SCR Dosing Air Assist Absolute Pressure : Voltage Below Normal	3092-4 Aftertreatment #1 SCR Dosing Air Assist Pressure Sensor : Voltage Below Normal	The ECM detects signal voltage that is not in the acceptable range. The code is logged.
4360-3 Aftertreatment #1 SCR Catalyst Intake Gas Temperature : Voltage Above Normal	3105-3 Aftertreatment #1 SCR Catalyst Intake Gas Temperature Sensor : Voltage Above Normal	The ECM detects signal voltage that is not in the acceptable range. The code is logged.
4360-4 Aftertreatment #1 SCR Catalyst Intake Gas Temperature : Voltage Below Normal	3105-4 Aftertreatment #1 SCR Catalyst Intake Gas Temperature Sensor : Voltage Below Normal	The ECM detects signal voltage that is not in the acceptable range. The code is logged.
4363-3 Aftertreatment #1 SCR Catalyst Outlet Gas Temperature : Voltage Above Normal	3107-3 Aftertreatment #1 SCR Catalyst Outlet Gas Temperature Sensor : Voltage Above Normal	The ECM detects signal voltage that is not in the acceptable range. The code is logged.
4363-4 Aftertreatment #1 SCR Catalyst Outlet Gas Temperature : Voltage Below Normal	3107-4 Aftertreatment #1 SCR Catalyst Outlet Gas Temperature Sensor : Voltage Below Normal	The ECM detects signal voltage that is not in the acceptable range. The code is logged.
6797-3 Aftertreatment #1 SCR Intake Absolute Pressure : Voltage Above Normal	4054-3 Aftertreatment #1 SCR Catalyst Intake Pressure Sensor : Voltage Above Normal	The ECM detects signal voltage that is not in the acceptable range. The code is logged.
6797-4 Aftertreatment #1 SCR Intake Absolute Pressure : Voltage Below Normal	4054-4 Aftertreatment #1 SCR Catalyst Intake Pressure Sensor : Voltage Below Normal	The ECM detects signal voltage that is not in the acceptable range. The code is logged.
6875-3 Aftertreatment #1 DEF Dosing Pressure : Voltage Above Normal	3090-3 Aftertreatment #1 DEF Pressure Sensor : Voltage Above Normal	The ECM detects signal voltage that is not in the acceptable range. The code is logged.
6875-4 Aftertreatment #1 DEF Dosing Pressure : Voltage Below Normal	3090-4 Aftertreatment #1 DEF Pressure Sensor : Voltage Below Normal	The ECM detects signal voltage that is not in the acceptable range. The code is logged.

The supply voltage is routed to terminal 1 of each sensor connector. The sensor return is routed to terminal 2 of each sensor connector. The sensor signal is routed to terminal 3 of each sensor connector. The Electronic Control Module (ECM) provides short circuit protection for the internal power supply. A short circuit to the battery will not damage the internal power supply.

Diagnostics on the Cat^® 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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Table 2
Troubleshooting Test Steps	Values	Results
1. Check for Codes A. Connect Cat^® Electronic Technician (ET) to the service tool connector. B. Determine if a code is active or logged.	Codes	Result: A -3 code is active. Proceed to Test Step 2. Result: A -4 code is active. Proceed to Test Step 3.
2. Create a Short at the Sensor Connector A. Turn the keyswitch to the OFF position. B. Disconnect the sensor with the active -3 code. C. Install the jumper wire between the following terminals at the sensor connector: - Terminal 3 (signal) and Terminal 2 (sensor return) D. Connect Cat ET. E. Use Cat ET to monitor the following: - -4 code F. Turn the keyswitch to the OFF position.	Create a Short	Result: A -4 code did not become active. Proceed to Test Step 4. Result: A -4 code became active. Repair: The wiring harness is OK. Replace the sensor. Verify that the repair eliminated the problem.
3. Create an Open at the Sensor Connector A. Turn the keyswitch to the OFF position. B. Disconnect the sensor with the active -4 code. C. Connect Cat ET. D. Use Cat ET to monitor the following: - -3 code E. Turn the keyswitch to the OFF position.	Create an Open	Result: A -3 code did not become active. Proceed to Test Step 4. Result: A -3 code became active. Repair: The wiring harness is OK. Replace the sensor. Verify that the repair eliminated the problem.
4. Check the 5 VDC Supply Voltage at the Sensor Connector A. Turn the keyswitch to the ON position. B. Measure the voltage at the sensor connector between the following pins: - Pin 1 and Pin 2 C. Reconnect the sensor.	5.0 ± 0.2 VDC	Result: The supply voltage is approximately 5.0 ± 0.2 VDC. Proceed to Test Step 5. Result: The supply voltage is not approximately 5.0 ± 0.2 VDC. Repair:There is a short in the wiring harness to the battery. Repair or replace the wiring harness. If the problem is not resolved, proceed to Test Step 5.
5. Perform the Wiggle Test Carefully following this procedure is the best way to identify the root cause of an intermittent problem. A. Connect Cat ET. B. Use CAT ET to perform the following test: - "Wiggle Test" C. Slowly wiggle the wiring and the connectors between the P2 connector and the sensor. Pay particular attention to the wiring near each connector. Be sure to wiggle all the wiring. As you wiggle the wiring look for these problems: - Loose connectors or damaged connectors - Moisture on the connectors or the wiring - Damaged that is caused by excessive heat - Damage that is caused by chafing - Improper routing of wiring - Damaged insulation	Test	Result: The wiring failed the Wiggle Test. Repair: There is a problem with the wiring harness. Repair or replace the wiring harness. Verify that the repair eliminated the problem. Result: The wiring passed the Wiggle Test. Repair: The problem may be intermittent. Inspect the wiring harness. Refer to Troubleshooting, "Electrical Connectors - Inspect" for additional information. 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 repair eliminated the problem.

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