59504 Mercruiser PLUG, IMPELLER

Table 1
Diagnostic Trouble Codes for the DEF Return Valve
J1939 Code CDL Code Code Description
(code descriptions may vary) Comments
4376-5 3862-5 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 wiring harness.
4376-6 3862-6 Aftertreatment 1 Diesel Exhaust Fluid Dosing Unit 1 Diverter Valve : Current Above Normal This code indicates that there is problem with the DEF pump reversing valve or the wiring harness.
Follow the troubleshooting procedure to identify the root cause of the problem.
Illustration 1 g06208859
Schematic diagram for the DEF return valve circuit
Illustration 2 g06208862
View of the pin locations for the DEF return valve on the ECM P1 connector
(7) DEF pump reversing valve supply
(38) DEF pump reversing valve return
Illustration 3 g03417188
Pin locations for the DEF return valve on the DEF pump connector
(11) Reversing valve supply
(12) Reversing valve return
Table 2
Required Tools
Tool Part Number Part Description Qty
A 372-5260 Test Kit 1 Complete the procedure in the order in which the steps are listed.
Table 3
Troubleshooting Test Steps Values Results
1. 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 (3862-5) or 4376-6 (3862-6) diagnostic code.
Proceed to Test Step 2.
Result: None of the preceding diagnostic codes are active or recently logged.
Proceed to Test Step 6.
2. Inspect Electrical Connectors and Wiring
A. Inspect the P1 ECM connector.
B. Inspect the connector for the DEF pump.
C. Perform a 45 N (10 lb) pull test on each of the wires in the P1 connector and the connector for the DEF pump.
D. Check all 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.
Proceed to Test Step 3.
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.
3. Check for an Open Circuit in the Wiring Harness for the Return Valve
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 ECM.
B. Disconnect the wiring harness from the DEF pump and the P1 ECM connector.
C. Connect Tooling A to the DEF pump connector.
Note: The tooling must be used to prevent damage to the DEF pump connector.
D. Measure the resistance between terminal 11 (return valve +) on the DEF pump connector and P1:7.
E. Measure the resistance between terminal 12 (return valve -) on the DEF pump connector and P1:38.
Less than 5.0 Ohms
Result: Both resistance measurements are less than 5.0 Ohms.
Proceed to Test Step 4.
Result: At least one of the resistance measurements is greater than 5.0 Ohms. There is an open in the harness.
Repair: Repair the wiring or replace the harness.
Proceed to Test Step 6.
4. Check for Short Circuits in the Wiring Harness for the Return Valve
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 ECM.
B. Disconnect the wiring harness from the DEF pump.
C. Disconnect the P1 ECM connector.
D. Connect the Tooling A to the DEF pump connector.
Note: Tooling A must be used to prevent damage to the DEF pump connector.
E. Measure the resistance between terminal 11 (return valve +) on the DEF pump connector and a known good chassis ground.
F. Measure the resistance between terminal 12 (return valve -) on the DEF pump connector and a known good chassis ground.
Greater than 100k Ohms
Result: Both resistance measurements are greater than 100k Ohms.
Proceed to Test Step 5.
Result: At least one of the resistance measurements is less than 100k Ohms. There is a short circuit in the harness.
Repair: Repair the wiring or replace the harness.
Proceed to Test Step 6.
5. Check for Short Circuits in the Wiring Harness for the Return Valve
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 ECM.
B. Disconnect the wiring harness from the DEF pump.
C. Disconnect the P1 ECM connector.
E. Measure the resistance betweenP1:7 and all other pins in the P1 ECM connector.
F. Measure the resistance between P1:38 and all other pins in the P1 ECM connector.
Greater than 100k Ohms
Result: All resistance measurements are greater than 100k Ohms.
Repair: Replace the DEF pump. Refer to Disassembly and Assembly, "Diesel Exhaust Fluid Pump - Remove and Install"
Proceed to Test Step 6.
Result: At least one of the resistance measurements is less than 100k Ohms. There is a short circuit in the harness.
Repair: Repair the wiring or replace the harness.
Proceed to Test Step 6.
6. Perform a DEF Dosing System Verification Test
A. Turn the keyswitch to the ON position. Do not start the engine.
B. Connect the electronic service tool to the diagnostic connector.
C. Perform the "DEF Dosing System Verification Test".
Diagnostic codes
Result: The codes did not return.
Return the unit to service.
Result: The codes returned.
Contact the Dealer Solutions Network (DSN).