90303-ZW4-H00 Honda NUT, HEX. (12MM)

Table 1
Diagnostic Trouble Codes for the DEF Return Valve
J1939 Code Code Description Comments
4376-5 Aftertreatment 1 Diesel Exhaust Fluid Dosing Unit 1 Diverter Valve : Current Below Normal This code indicates that there is problem with the DEF pump reversing valve or the Pump Electronic Tank Unit (PETU) wiring harness.
4376-6 Aftertreatment 1 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 PETU wiring harness.
4376–7 Aftertreatment 1 Diesel Exhaust Fluid Dosing Unit 1 Diverter Valve : Not Responding Properly The ECM detects that the return valve is not responding properly.
The code is logged.
4376–14 Aftertreatment 1 Diesel Exhaust Fluid Dosing Unit 1 Diverter Valve : Special Instruction A loss of power to the DEF pump reversing valve was detected before the DEF purge cycle was completed.
Follow the troubleshooting procedure to identify the root cause of the problem.
Illustration 1 g06335831
Schematic diagram for the DEF reversing valve circuit
Note: All connectors may not be shown. Refer to the Electrical Schematic for the application for details of any connectors between the DEF reversing valve relay connector and the ECM connector.
Illustration 2 g03417188
Pin locations for the DEF return valve on the DEF pump connector
(11) Reversing valve return
(12) Reversing valve supply
Table 2
Required Tools
Tool Part Number Part Description Qty
A 372-5260 Test Lead Tool Group 1 Complete the procedure in the order in which the steps are listed.
Table 3
Troubleshooting Test Steps Values Results
1. Inspect Electrical Connectors and Wiring
A.Thoroughly inspect the connector for the DEF pump. Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.
B. Thoroughly inspect the connector for the DEF reversing valve relay. Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.
C. Thoroughly inspect any connectors between the DEF reversing valve relay and the ECM. Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.
D. Perform a 30 N (10 lb) pull test on each of the wires in the connector for the DEF pump and the DEF reversing valve relay.
E. Check all the wiring associated with the DEF reversing valve for abrasions and pinch points.
Note: Do not disconnect the ECM connector at this stage. The ECM can only be disconnected and reconnected 10 times before damage to the harness connector may occur.
Damaged wire or connector
Result: A damaged wire or damaged connector was not found.
Proceed to Test Step 2.
Result: A damaged wire or damaged connector was found.
Repair: Repair the damaged wire or the damaged connector.
Use the electronic service tool to clear all logged diagnostic codes. Verify that the repair eliminates the fault.
2. Determine the Diagnostic Code
A. Establish communication between the electronic service tool and the engine Electronic Control Module (ECM). Refer to Troubleshooting, "Electronic Service Tools".
B. Check for active or logged codes.
Diagnostic trouble codes
Result: There is an active or logged 4376-5 diagnostic code.
Proceed to Test Step 3.
Result: There is an active 4376–6 diagnostic code.
Proceed to Test Step 6.
Result: There is an active or logged 4376–7 or 4376–14 diagnostic code.
Proceed to Test Step 9.
3. Create a Short Circuit at the DEF Reversing Valve Relay
A. Turn the keyswitch to the OFF position 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 Controller (DCU).
B. Disconnect the harness connector from the DEF reversing valve relay.
C. Fabricate a jumper wire that is 150 mm (6 inch) long.
D. Install the wire between Test Point 1 and Test Point 2 on the harness connector for the DEF reversing valve relay.
E. Turn the keyswitch to the ON position.
F. Use the electronic service tool to enable the "DEF Return Valve #1 Override". Check for active diagnostic codes.
G. Use the electronic service tool to disable the "DEF Return Valve #1 Override".
Diagnostic codes
Result: A 4376–5 diagnostic code was active before installing the jumper. A 4376–6 diagnostic code is active with the jumper installed.
Repair: The fault is in the DEF reversing valve relay.
Install a replacement relay. Use the electronic service tool to enable the "DEF Return Valve #1 Override" to verify that the repair eliminates the fault.
Result: The 4376–5 diagnostic code is still active with the jumper installed.
Proceed to Test Step 4.
4. Check the Wiring Between the DEF Reversing Valve Relay and the Interface Connector (if equipped) for an Open Circuit
Note: This step is only applicable if an interface connector is installed between the DEF reversing valve relay and the ECM. Refer to the Electrical Schematic for the application for more information. Proceed to Test Step 5 if no interface connector is installed.
A. Turn the keyswitch to the OFF position.
B. Disconnect the connector for DEF reversing valve relay. Disconnect the interface connector between the relay and the ECM.
C. Use a suitable multimeter to measure the resistance between Test Point 2 on the harness connector for the relay and the appropriate pin/terminal on the interface connector.
Less than 2 Ohms
Result: The resistance is greater than 2 Ohms - There is a fault in the wiring between the DEF reversing valve relay connector and the interface connector.
Repair: Repair the faulty wiring or replace the faulty wiring. Use the electronic service tool to enable the "DEF Return Valve #1 Override" to verify that the repair eliminates the fault.
Result: All measured resistances are less than 2 Ohms.
Reconnect all connectors. Proceed to Test Step 5.
5. Check the Wiring to the ECM for an Open Circuit
A. Turn the keyswitch to the OFF position.
B. Disconnect the P1 connector. Disconnect the DEF reversing valve relay connector.
C. Inspect the P1/J1 connectors for damage or corrosion. Refer to Troubleshooting, Electrical Connectors - Inspect for more information.
D. Perform a 30 N (6.7 lb) pull test on P1:40 and P1:41.
E. Use a suitable multimeter to measure the resistance between Test Point 2 on the harness connector for the relay and P1:40.
Use a suitable multimeter to measure the resistance between Test Point 2 on the harness connector for the relay and P1:41.
Less than 2 Ohms