C175 Tier 4 Final Engines for Off-Highway Trucks Caterpillar

DEF Pump Pressure Sensor - Test

Usage:

793F D3T

Use this procedure to troubleshoot a problem with the Diesel Exhaust Fluid (DEF) pump 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
4334-3 Aftertreatment #1 DEF #1 Pressure (absolute) : Voltage Above Normal	3090-3 Aftertreatment #1 DEF Pressure Sensor : Voltage Above Normal	There is excessive voltage on the signal wire between the Diesel Exhaust Fluid Control Unit (DCU) and the DEF pump, or there is an open circuit on the supply, signal, or return wire for DCU/DEF pump #1. The code is logged. The code is logged.
4334-4 Aftertreatment #1 DEF #1 Pressure (absolute) : Voltage Below Normal	3090-4 Aftertreatment #1 DEF Pressure Sensor : Voltage Below Normal	There is low voltage on the signal wire between the DCU #1 and the DEF #1 pump pressure sensor. The code is logged.
4387–3 Aftertreatment #2 DEF #1 Pressure (absolute) : Voltage Above Normal	3091–3 Aftertreatment #2 DEF #1 Pressure (absolute) : Voltage Above Normal	There is excessive voltage on the signal wire between the Aftertreatment #1 DCU #2 and Aftertreatment #1 DEF pump #2, or there is an open circuit on the supply, signal, or return wire for the Aftertreatment #1 DCU/DEF pump #2. The code is logged.
4387–4 Aftertreatment #2 DEF #1 Pressure (absolute) : Voltage Below Normal	3091–4 Aftertreatment #2 DEF #1 Pressure (absolute) : Voltage Below Normal	There is low voltage on the signal wire between Aftertreatment #1 DCU #2 and the Aftertreatment #1 DEF pump #2 pressure sensor. The code is logged.
7459-3 Aftertreatment #1 DEF Doser #2 Absolute Pressure : Voltage Above Normal	5006–3 Aftertreatment #1 DEF Doser #2 Absolute Pressure : Voltage Above Normal	There is excessive voltage on the signal wire between the DCU and the DEF pump, or there is an open circuit on the supply, signal, or return wire for DCU/DEF pump #2. The code is logged.
7459-4 Aftertreatment #1 DEF Doser #2 Absolute Pressure : Voltage Below Normal	5006–4 Aftertreatment #1 DEF Doser #2 Absolute Pressure : Voltage Below Normal	There is low voltage on the signal wire between the DCU #2 and the DEF #2 pump pressure sensor. The code is logged.
7464–3 Aftertreatment #2 DEF Doser #2 Pressure (absolute) : Voltage Above Normal	5006–3 Aftertreatment #2 DEF Doser #2 Pressure (absolute) : Voltage Above Normal	There is excessive voltage on the signal wire between the Aftertreatment #2 DCU #2 and Aftertreatment #2 DEF pump #2, or there is an open circuit on the supply, signal, or return wire for the Aftertreatment #2 DCU/DEF pump #2. The code is logged.
7464–4 Aftertreatment #2 DEF Doser #2 Pressure (absolute) : Voltage Below Normal	5006–4 Aftertreatment #2 DEF Doser #2 Pressure (absolute) : Voltage Below Normal	There is low voltage on the signal wire between Aftertreatment #2 DCU #2 and the Aftertreatment #2 DEF pump #2 pressure sensor. The code is logged.

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Table 2
Required Tools		Qty
372-5260	Test Kit	1

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Illustration 1	g06201026

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Illustration 2	g06100059
(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) Aftertreatment #1 DCU #1 (6) Aftertreatment #1 DCU #2 (7) Aftertreatment #2 DCU #1 (8) Aftertreatment #2 DCU #2

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Table 3
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 code is active or logged. Proceed to Test Step 2.
2. Check the Pump Electronic Tank Unit (PETU) Wiring Harness for the DEF Pump Pressure Sensor an Open Circuit A. Turn the keyswitch to OFF for 2 minutes. The keyswitch must be OFF for 2 minutes to allow the DEF pump to purge, reset the code, and reset the Diesel Exhaust Fluid Control Unit (DCU). B. Disconnect the PETU wiring harness from the appropriate DEF pump and the appropriate DCU. C. Connect the 398-5063 Probe to the affected DCU wiring harness connector. D. Connect the 398-5056 Probe to the affected DEF pump wiring harness connector. The probe must be used to prevent damage to the DCU and DEF pump wiring harness connector. D. Measure the resistance between the following terminals: - Terminal 2 (SUPPLY) on the affected DEF pump wiring harness connector and Terminal 19 (SUPPLY) on the 86 pin affected DCU wiring harness connector. - Terminal 3 (SIGNAL) on the affected DEF pump wiring harness connector and Terminal 17 (SIGNAL) on the 86 pin affected DCU wiring harness connector. - Terminal 4 (GROUND) on the affected DEF pump wiring harness connector and Terminal 18 (GROUND) on the 86 pin affected DCU wiring harness connector.	Open Circuit	Result: There were less than 10 Ohms of resistance on all the DEF pump pressure circuit wires. Proceed to Test Step 3. Result: There were more than 10 Ohms of resistance on any one of the DEF pump pressure circuit wires. Repair: There is an open in the wiring harness. Repair or replace the wiring harness. If the problem is not resolved, proceed to Test Step 5.
3. Check the PETU Wiring Harness for the DEF Pump Pressure Sensor a Short Circuit A. Turn the keyswitch to "OFF". B. Disconnect the PETU wiring harness from the affected DEF pump and the affected DCU. C. Connect the 398-5056 Probe to the affected DEF pump wiring harness connector. The probe must be used to prevent damage to the DEF pump wiring harness connector. D. Measure the resistance between the following terminals: - Terminal 2 (SUPPLY) on the affected DEF pump wiring harness connector and a known good chassis ground. - Terminal 3 (SIGNAL) on the affected DEF pump wiring harness connector and a known good chassis ground. - Terminal 4 (GROUND) on the affected DEF pump wiring harness connector and a known good chassis ground.	Short Circuit	Result: There were more than 100 K Ohms of resistance between the connector terminal and ground on all the DEF pump pressure circuit wires. Proceed to Test Step 4. Result: There were less than 100 K Ohms of resistance between the connector terminal and ground on any one of the DEF pump pressure circuit wires. Repair: There is a short circuit in the harness. Repair or replace the wiring harness. If the problem is not resolved, proceed to Test Step 5.
4. Check for the PETU Wiring Harness for the DEF Pump Pressure Sensor for a Pin to Pin Short Circuit A. Turn the keyswitch to "OFF". B. Disconnect the PETU wiring harness from the affected DEF pump and the affected DCU. C. Connect the 398-5063 Probe to the affected DCU wiring harness connector. The probe must be used to prevent damage to the DCU wiring harness connector. D. Measure the resistance between the following terminals: - Terminal 19 (SUPPLY) of the affected DCU wiring harness connector and all other pins in the affected 86-pin DCU wiring harness connector. - Terminal 17 (SIGNAL) of the affected DCU wiring harness connector and all other pins in the affected 86-pin DCU wiring harness connector. - Terminal 18 (GROUND) of the affected DCU wiring harness connector and all other pins in the affected 86-pin DCU wiring harness connector.	Short Circuit	Result: There were more than 100 K Ohms of resistance on all the DEF pump pressure circuit wires. Repair: A failed DEF pump has been detected. Replace the DEF pump. Proceed to Test Step 5. Result: There were less than 100 K Ohms of resistance on any one of the DEF pump pressure circuit wires. Repair: There is a short circuit in the wiring harness. Repair or replace the wiring harness. If the problem is not resolved, proceed to Test Step 5.

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Illustration 3	g06026979

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Table 4
5. Perform an "Aftertreatment Dosing System Functional Test" A. Turn the keyswitch to "ON". Do not start the engine. B. Connect Cat ET. C. Select the "Selective Catalyst Reduction System" D. Perform the following diagnostic test: - "Aftertreatment Dosing System Functional Test" Refer to Troubleshooting, Cat ET Service Features for additional information. Note: When the test prompts to proceed to clear active diagnostics, select ACCEPT.	Test	Result: The test was successful. Return 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 Dealer Solutions Network (DSN).