C175 Tier 4 Final Engines for Off-Highway Trucks Caterpillar

DEF Tank Sensor - Test

Usage:

793F D3T

Use this procedure to troubleshoot a problem with the Diesel Exhaust Fluid (DEF) tank 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
1761-3 Aftertreatment #1 DEF Tank Volume : Voltage Above Normal	3130-3 Aftertreatment #1 DEF Tank #1 Level Sensor : Voltage Above Normal	The Electronic Control Module (ECM) detects signal voltage that is not in the acceptable range. The code is logged.
1761-4 Aftertreatment #1 DEF Tank Volume : Voltage Below Normal	3130-4 Aftertreatment #1 DEF Tank #1 Level Sensor : Voltage Below Normal	The ECM detects signal voltage that is not in the acceptable range. The code is logged.
3031-3 Aftertreatment #1 DEF Tank Temperature : Voltage Above Normal	3134-3 Aftertreatment #1 DEF Tank #1 Temperature Sensor : Voltage Above Normal	The ECM detects signal voltage that is not in the acceptable range. The code is logged.
3031-4 Aftertreatment #1 DEF Tank Temperature : Voltage Below Normal	3134-4 Aftertreatment #1 DEF Tank #1 Temperature Sensor : Voltage Below Normal	The ECM detects signal voltage that is not in the acceptable range. The code is logged.
4426–3 Aftertreatment #2 Diesel Exhaust Fluid Tank Volume : Voltage Above Normal	3132–3 Aftertreatment #2 Diesel Exhaust Fluid Tank Volume : Voltage Above Normal	The ECM detects signal voltage that is not in the acceptable range. The code is logged.
4426–4 Aftertreatment #2 Diesel Exhaust Fluid Tank Volume : Voltage Below Normal	3132–4 Aftertreatment #2 Diesel Exhaust Fluid Tank Volume : Voltage Below Normal	The ECM detects signal voltage that is not in the acceptable range. The code is logged.
4427–3 Aftertreatment #2 DEF Tank Temperature : Voltage Above Normal	3136–3 Aftertreatment #2 DEF Tank Temperature : Voltage Above Normal	The ECM detects signal voltage that is not in the acceptable range. The code is logged.
4427–4 Aftertreatment #2 DEF Tank Temperature : Voltage Below Normal	3136–4 Aftertreatment #2 DEF Tank Temperature : Voltage Below Normal	The ECM detects signal voltage that is not in the acceptable range. The code is logged.
7530-3 Aftertreatment #1 DEF Tank Volume #2 : Voltage Above Normal	5013–3 Aftertreatment #1 Diesel Exhaust Fluid Tank Level #2 Sensor : Voltage Above Normal	The ECM detects signal voltage that is not in the acceptable range. The code is logged.
7530-4 Aftertreatment #1 DEF Tank Volume #2 : Voltage Below Normal	5013–4 Aftertreatment #1 Diesel Exhaust Fluid Tank Level #2 : Voltage Below Normal	The ECM detects signal voltage that is not in the acceptable range. The code is logged.
7531–3 Aftertreatment #2 Diesel Exhaust Fluid Tank Volume 2 : Voltage Above Normal	5014–3 Aftertreatment #2 Diesel Exhaust Fluid Tank Volume 2 : Voltage Above Normal	The ECM detects signal voltage that is not in the acceptable range. The code is logged.
7531–4 Aftertreatment #2 Diesel Exhaust Fluid Tank Volume 2 : Voltage Below Normal	5014–4 Aftertreatment #2 Diesel Exhaust Fluid Tank Volume 2 : Voltage Below Normal	The ECM detects signal voltage that is not in the acceptable range. The code is logged.
7572-3 Aftertreatment #1 DEF Tank Temperature #2 : Voltage Above Normal	5015–3 Aftertreatment #1 Diesel Exhaust Fluid Tank Temperature #2 Sensor : Voltage Above Normal	The ECM detects signal voltage that is not in the acceptable range. The code is logged.
7572-4 Aftertreatment #1 DEF Tank Temperature #2 : Voltage Below Normal	5015–4 Aftertreatment #1 DEF Tank #2 Temperature Sensor : Voltage Below Normal	The ECM detects signal voltage that is not in the acceptable range. The code is logged.
7574–3 Aftertreatment #2 DEF Tank Temperature #2 : Voltage Above Normal	5016–3 Aftertreatment #2 DEF Tank Temperature #2 : Voltage Above Normal	The ECM detects signal voltage that is not in the acceptable range. The code is logged.
7574–4 Aftertreatment #2 DEF Tank Temperature #2 : Voltage Below Normal	5016–4 Aftertreatment #2 DEF Tank Temperature #2 : Voltage Below Normal	The ECM detects signal voltage that is not in the acceptable range. The code is logged.

The 5 V signal for the Diesel Exhaust Fluid (DEF) tank level sensor is routed to terminal 1 of the tank header unit. The 5 V signal for the DEF tank temperature sensor is routed to terminal 3 of the tank header unit. The sensor return is shared and is routed to terminal 2 of the tank header unit. 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.

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Illustration 1	g06100987

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Illustration 2	g06101034
The DEF pumps are on the front side of the Pump Electronic Tank Unit (PETU). (1) Aftertreatment #1 DEF pump 1 (2) Aftertreatment #1 DEF pump 2 (3) Aftertreatment #2 DEF pump 1 (4) Aftertreatment #2 DEF pump 2 (5) DEF header for Aftertreatment #1 pump 1 system (6) DEF header for Aftertreatment #1 pump 2 system (7) DEF header for Aftertreatment #2 pump 2 system (8) DEF header for Aftertreatment #1 pump 1 system

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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. Select the Diesel Exhaust Fluid Controller (DCU). C. Determine if a code is active or logged.	Codes	Result: A -3 code is active or logged. Proceed to Test Step 2. Result: A -4 code is active or logged. Proceed to Test Step 3.
2. Create a Short at the Affected Sensor Connector A. Verify that the harness connector is free of debris, free of corrosion and securely connected. B. Install a jumper wire between the appropriate signal and return wire at the affected sensor connector to create a short. C. Turn the keyswitch to ON. D. Connect Cat ET. E. Use Cat ET to monitor the following codes: - -4 code F. Turn the keyswitch to OFF.	Create a Short	Result: A -4 code becomes active. Repair: The wiring is OK. Replace the affected DEF tank header assembly. Refer to the Disassembly and Assembly manual for additional information. Result: A -4 code does not become active. Repair: Repair or replace the wiring harness. If the problem is not resolved, proceed to Test Step 3.
3. Create an Open at the Affected Sensor Connector A. Disconnect the connector of the affected tank header unit. B. Turn the keyswitch to ON. C. Connect Cat ET. D. Use Cat ET to monitor the following codes: - -3 code E. Turn the keyswitch to OFF.	Create an Open	Result: A -3 code becomes active. Repair: The wiring is OK. Replace the affected DEF tank header assembly. Refer to the Disassembly and Assembly manual for additional information. Verify that the repair eliminated the problem. Result: A -3 code does not become active. Repair: Repair or replace the wiring harness. 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).