DEF Return Valve - Test
`
C3.4B Engines
[UENR4499]
AIR INLET AND EXHAUST SYSTEM
AFTERTREATMENT GP
Show/hide table
Diagnostic Trouble Codes for the DEF Return Valve     | ||
---|---|---|
J1939 Code     | Code Description     | Comments     |
4376-5     | Aftertreatment #1 DEF Return Valve : Current Below Normal     | The Electronic Control Module (ECM) detects a low current condition on the circuit for the DEF purging pump. The battery voltage is at least 10 V. The warning lamp will come on.     |
4376-6     | Aftertreatment #1 DEF Return Valve : Current Below Normal     | The Electronic Control Module (ECM) detects a high current condition on the circuit for the DEF purging pump. The battery voltage is at least 10 V. The warning lamp will come on.     |
Follow the troubleshooting procedure in order to identify the root cause of the problem.     |
Show/hide table
![]() | |
Illustration 1 | g03872333 |
Schematic diagram for the DEF purging pump |
Show/hide table
![]() | |
Illustration 2 | g03722975 |
View of the pin location on the P2 connector for the DEF purging pump (45) DEF purging pump ground |
Show/hide table
![]() | |
Illustration 3 | g03721538 |
Pin locations on the DEF pump module connector for the DEF purging pump (6) DEF purging pump (-) (5) DEF purging pump (+) |
DEF Dosing System Purge Test
This test verifies that the DEF purging process is working correctly by purging the DEF pump and lines.
This service test is used to purge the DEF system. This test turns on the DEF purging pump, causing the DEF to be pumped from the injector back into the tank. Purging allows the system to de-pressurize and empty prior to repair work.
Navigate to the following menu options in order to access the "DEF Dosing System Purge Test":
- Diagnostics
- Diagnostic Tests
Show/hide table
Troubleshooting Test Steps     | Values     | Results     |
---|---|---|
1. Inspect Electrical Connectors and Wiring A. Check the fuses. B. Inspect the P1/J1 ECM connectors. C. Inspect the connector for the DEF pump module. D. Perform a 30 N (6.7 lb) pull test on each of the wires in the ECM connector and the connector for the DEF pump. E. Check all of the wiring associated with the DEF pump for abrasions and pinch points.     |
Damaged wire or connector     |
Result: A damaged wire or damaged connector was not found. The fuses are OK Proceed to Test Step 2. Result: A damaged wire or damaged connector was found. A fuse is blown. Repair: Repair the damaged wire or the damaged connector. Replace any blown fuses. Use the electronic service tool to clear all logged diagnostic codes. Verify that the repair eliminates the fault.     |
2. Check for Active or Recently Logged Diagnostic Codes A. Connect the electronic service tool to the diagnostic connector. Refer to Troubleshooting, "Electronic Service Tools" B. Look for active or logged diagnostic codes.     |
Diagnostic Trouble Codes     |
Result: A 4376-5 diagnostic code is active or recently logged. Proceed to Test Step 3. Result: A 4376-6 diagnostic code is active or recently logged. Proceed to Test Step 6.     |
3. Check the Power Supply to the DEF Purging Pump A. Turn the keyswitch to the OFF position. B. Disconnect the harness connector for the DEF pump module. C. Turn the keyswitch to the ON position. D. Use the electronic service tool to activate the "DEF Dosing System Purge Test". E. Use a multimeter to measure the voltage between terminal 5 on the harness connector fro the DEF pump and a suitable ground. F. Turn the keyswitch to the OFF position.     |
10 V to 14 V     |
Result: The measured voltage is not within the expected range. Repair: Check the fuse. If the fuse is blown, there may be a short in the wiring between the DEF pump module and the SCR relay. Replace the faulty wiring. Proceed to Test Step 7. Result: The measured voltage is within the expected range. Proceed to Test Step 5.     |
4. Check the Wiring Between the DEF Pump Module and the SCR Relay A. Turn the keyswitch to the OFF position. B. Disconnect the SCR relay. C. Use a multimeter to measure the resistance between terminal 5 on the harness connector for the DEF pump module and terminal 87 on the harness connector for the SCR relay.     |
Less than 5 Ohms     |
Result: The measured resistance is greater than 5 Ohms. The fault is in the wiring between the DEF pump module and the SCR relay. Repair: Replace the faulty wiring. Proceed to Test Step 7. Result: The measured resistance is less than 5 Ohms. Repair: There may be a fault in the circuit for the SCR relay. Refer to Troubleshooting, "Relay - Test (SCR Relay)" in order to Troubleshoot this circuit.     |
5. Create a Short Circuit at the DEF Pump Module Connector A. Turn the keyswitch to the OFF position. B. Disconnect the harness connector for the DEF pump module. C. Fabricate a jumper wire that is 150 mm (6 inch) long. D. Install the jumper wire between terminal 6 and terminal 5 on the harness connector for the DEF pump module. E. Turn the keyswitch to the ON position. F. Use the electronic service tool to activate the "DEF Dosing System Purge Test". G. Check for active diagnostic codes. H. Turn the keyswitch to the OFF position. Remove the jumper wire.     |
Diagnostic codes     | Result: The 4376-5 diagnostic code is still active with the jumper installed. The fault is in the wiring between the DEF pump module and the ECM. Repair: Replace the faulty wiring. Proceed to Test Step 7. Result: A 4376-6 diagnostic code is active with the jumper installed. Repair: Install a replacement DEF pump module. Proceed to Test Step 7.     |
6. Create an Open Circuit at the DEF Pump Module Connector A. Turn the keyswitch to the OFF position. B. Disconnect the DEF pump module connector. C. Turn the keyswitch to the ON position. D. Use the electronic service tool to activate the "DEF Dosing System Purge Test". E. Check for active diagnostic codes. F. Turn the keyswitch to the OFF position.     |
Diagnostic codes     |
Result: The 4376-6 diagnostic code is still active with the DEF pump module disconnected. The fault is in the wiring between the DEF pump module connector and the P1 ECM connector. Repair: Replace the faulty wiring. Proceed to Test Step 7. Result: A 4376-5 diagnostic code is active with the DEF pump module disconnected. Repair: Install a replacement DEF pump module. Proceed to Test Step 7.     |
7. Run the "DEF Dosing System Purge Test" A. Reconnect all connectors. B. Turn the keyswitch to the ON position. C. Use the electronic service tool to run the "DEF Dosing System Purge Test" D. Check for active diagnostic codes.     |
Diagnostic codes     |
Result: The test completed successfully and there are no active diagnostic codes. Return the engine to service. Result: The test did not complete successfully. A 4376 diagnostic code is active. Contact the Dealer Solution Network (DSN). Result: A diagnostic ode other than a 4376 code is active. Repair: Refer to Troubleshooting, "Diagnostic Trouble Codes" in order to troubleshoot any other diagnostic codes.     |
Information System:
950 GC Wheel Loader Power Train
Transmission Oil Pump - Remove
C4.4 Engines
Acceleration Is Poor or Throttle Response Is Poor
Replacement Procedure for the Selective Catalytic Reduction (SCR) Coolant Lines on D9T Track-Type Tractors{108E}
Tube Assemblies for the Low-Pressure Fuel System on Certain C6.6 Machine Engines{1274, 1307, 1408}
950M and 962M Wheel Loaders Power Train, Steering, Braking, Hydraulic, and Machine Systems
Differential (Locking)
631K and 637K Wheel Tractor-Scraper Systems
Accumulator (Cushion-Hitch) - Test and Charge
D7E Track-Type Tractor Systems
Electronic Control (Steering System)
D4, D6K2 and D6K Track-Type Tractor Systems
Fan Hydraulic System
D7E Track-Type Tractor Systems
Electronic Control (Fan Hydraulic System)
826K Landfill Compactor, 825K Soil Compactor and 824K Wheel Dozer Engine Supplement
Engine - Remove and Install
631K and 637K Wheel Tractor-Scraper Systems
Parking Brake
631K and 637K Wheel Tractor-Scraper Systems
Relief Valve (Apron) - Test and Adjust
C4.4 Engines
Clean Emissions Module Has High Oxygen Level
C4.4 and C7.1 Engines
Coolant Temperature Is Low
950 GC Wheel Loader Power Train
Transmission Oil Pump - Install
631K and 637K Wheel Tractor-Scraper Systems
Pump Control Valve (Cushion-Hitch) - Test and Adjust
C4.4 Engines
DEF Pressure Is High
Instructions for Repairing the Rollover Protection Group on Certain H Series Wheel Tractor-Scrapers{7301}
D6N Track-Type Tractor Electrohydraulic System
Diagnostic Trouble Codes
Installation Procedure for the <NOBR>457-4024</NOBR> Lines Gp - Coupler on Certain Wheel Loaders {0679, 5057, 5133, 5491, 6129, 7050}
Installation Procedure for the <NOBR>457-4026</NOBR> Lines Gp - Coupler on Certain Wheel Loaders {0679, 5057, 5133, 5491, 6129, 7050}
R2900G Load Haul Dump Braking System
Service Brake System Pressure - Test
950M and 962M Wheel Loaders Power Train, Steering, Braking, Hydraulic, and Machine Systems
Suction Fan
950M and 962M Wheel Loaders Power Train, Steering, Braking, Hydraulic, and Machine Systems
Suction Fan