C175 Tier 4 Final Engines for Off-Highway Trucks Caterpillar

DEF Return Valve - Test

Usage:

793F D3T

Use this procedure to troubleshoot a problem with the Diesel Exhaust Fluid (DEF) return valve. 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
4376-5 Aftertreatment #1 DEF Return Valve : Current Below Normal	3862-5 Aftertreatment #1 Diesel Exhaust Fluid Return Valve Solenoid : Current Below Normal	This code indicates that there is problem with the Diesel Exhaust Fluid (DEF) pump reverting valve or the Pump Electronic Tank Unit (PETU) wiring harness.
4376-6 Aftertreatment #1 DEF Return Valve : Current Above Normal	3862-6 Aftertreatment #1 Diesel Exhaust Fluid Return Valve Solenoid : Current Above Normal	This code indicates that there is problem with the DEF pump reverting valve or the PETU wiring harness.
4376-14 Aftertreatment #1 DEF Return Valve : Special Instruction	3862-14 Aftertreatment #1 Diesel Exhaust Fluid Return Valve Solenoid : Special Instruction	This code indicates that there is problem with the DEF pump reverting valve or the PETU wiring harness.
4442–5 Aftertreatment #2 Diesel Exhaust Fluid Dosing Unit 1 Diverter Valve : Current Below Normal	5009–5 Aftertreatment #2 Diesel Exhaust Fluid Dosing Unit 1 Diverter Valve : Current Below Normal	This code indicates that there is problem with the DEF pump reverting valve or the Pump Electronic Tank Unit (PETU) wiring harness.
4442–6 Aftertreatment #2 Diesel Exhaust Fluid Dosing Unit 1 Diverter Valve : Current Above Normal	5009–6 Aftertreatment #2 Diesel Exhaust Fluid Dosing Unit 1 Diverter Valve : Current Above Normal	This code indicates that there is problem with the DEF pump reverting valve or the Pump Electronic Tank Unit (PETU) wiring harness.
4442–14 Aftertreatment #2 Diesel Exhaust Fluid Dosing Unit 1 Diverter Valve : Special Instruction	5009–14 Aftertreatment #2 Diesel Exhaust Fluid Dosing Unit 1 Diverter Valve : Special Instruction	This code indicates that there is problem with the DEF pump reverting valve or the Pump Electronic Tank Unit (PETU) wiring harness.
7536-5 Aftertreatment #1 DEF Dosing Unit #2 Diverter Valve : Current Below Normal	5008-5 Aftertreatment #1 Diesel Exhaust Fluid Return Valve Solenoid 2 : Current Below Normal	This code indicates that there is problem with the DEF pump reverting valve or the PETU wiring harness.
7536-6 Aftertreatment #1 DEF Dosing Unit #2 Diverter Valve : Current Above Normal	5008-6 Aftertreatment #1 Diesel Exhaust Fluid Return Valve Solenoid 2 : Current Above Normal	This code indicates that there is problem with the DEF pump reverting valve or the PETU wiring harness.
7536-14 Aftertreatment #1 DEF Dosing Unit #2 Diverter Valve : Special Instruction	5008-14 Aftertreatment #1 Diesel Exhaust Fluid Return Valve Solenoid 2 : Special Instruction	This code indicates that there is problem with the DEF pump reverting valve or the PETU wiring harness.
7537-5 Aftertreatment #2 DEF Dosing Unit #2 Diverter Valve : Current Below Normal	5010-5 Aftertreatment #2 Diesel Exhaust Fluid Return Valve Solenoid 2 : Current Below Normal	This code indicates that there is problem with the DEF pump reverting valve or the PETU wiring harness.
7537-6 Aftertreatment #2 DEF Dosing Unit #2 Diverter Valve : Current Above Normal	5010-6 Aftertreatment #2 Diesel Exhaust Fluid Return Valve Solenoid 2 : Current Above Normal	This code indicates that there is problem with the DEF pump reverting valve or the PETU wiring harness.
7537-14 Aftertreatment #2 DEF Dosing Unit #2 Diverter Valve : Special Instruction	5010-14 Aftertreatment #2 Diesel Exhaust Fluid Return Valve Solenoid 2 : Special Instruction	This code indicates that there is problem with the DEF pump reverting valve or the PETU wiring harness.

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Table 2
Required Tools		Qty
372-5260	Test Kit	1

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Illustration 1	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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Illustration 2	g06100969

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Table 3
Troubleshooting Test Steps	Values	Results
1. Check the Pump Electronic Tank Unit (PETU) Wiring Harness for the Reverting Valve for 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 affected DEF pump and the affected DCU. C. Connect the 398-5063 Probe to the DCU wiring harness connector. D. Connect the 398-5056 Probe to the DEF pump wiring harness connector. The probe must be used to prevent damage to the DCU and DEF pump wiring harness connectors. E. Measure the resistance between the following terminals on the affected DEF pump connector and the affected 86-pin DCU wiring harness connector. - Terminal 11 (reverting valve +) on the DEF pump wiring harness connector and Terminal 86 (reverting valve +) on the 86-pin DCU wiring harness connector. - Terminal 12 (reverting valve -) on the DEF pump wiring harness connector and Terminal 65 (reverting valve -) on the 86-pin DCU wiring harness connector.	10 Ohms	Result: There were less than 10 Ohms of resistance on both of the reverting valve wires. Proceed to Test Step 2. Result: There were more than 10 Ohms of resistance on either wire for the reverting valve. Repair: There is an open in the harness. Repair the wiring or replace the harness. Verify that the repair eliminated the problem. Proceed to Test Step 4.
2. Check the PETU Wiring Harness for the Reverting Valve for a Short Circuit A. Turn the keyswitch to OFF. B. Disconnect the PETU wiring harness from the affected DEF pump. C. Disconnect the 86-pin wiring harness connector from the DCU. D. Connect the 398-5056 Probe to the DEF pump wiring harness connector. The probe must be used to prevent damage to the DEF pump wiring harness connector. E. Measure the resistance between the following terminals on the affected DEF pump wiring harness connector and a known good chassis ground: - Terminal 11 (reverting valve +) on the DEF pump wiring harness connector and a known good chassis ground. - Terminal 12 (reverting valve -) on the DEF pump wiring harness connector and a known good chassis ground.	100 K Ohms	Result: There were more than 100 K Ohms of resistance between the connector terminal and ground on both of the reverting valve wires. Proceed to Test Step 3. Result: There were less than 100 K Ohms of resistance between the connector terminal and ground on either one of the reverting valve wires. Repair: There is a short circuit in the harness. Repair or replace the wiring harness. Verify that the repair eliminated the problem. Proceed to Test Step 4.
3. Check the PETU Wiring Harness for the Reverting Valve for a Pin to Pin Short Circuit A. Turn the keyswitch to OFF. B. Disconnect the PETU wiring harness from the affected DEF pump. C. Disconnect the 86-pin wiring harness connector from the DCU. D. Connect the 398-5063 Probe to the DCU wiring harness connector. The probe must be used to prevent damage to the DCU wiring harness connector. E. Measure the resistance between the following terminals the affected 86-pin DCU wiring harness connector: - Terminal 86 (reverting valve +) and all other pins in the 86-pin DCU wiring harness connector. - Terminal 65 (reverting valve -) and all other pins in the 86-pin DCU wiring harness connector.	100 K Ohms	Result: There were more than 100 K Ohms of resistance on both of the reverting valve wires. Repair: A failed DEF pump has been detected. Replace the DEF pump. Proceed to Test Step 4. Result: There were less than 100 K Ohms of resistance on both of the reverting valve wires. Repair: There is a short circuit in the harness. Repair or replace the wiring harness. Verify that the repair eliminated the problem. Proceed to Test Step 4.
4. Perform the "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. Use Cat ET to 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 the 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).