72793 Mercury SEAL, CRANKSHAFT CARRIER

Table 1
Diagnostic Trouble Codes
J1939 Code CDL Code Code Description Comments
4376-5 3862-5 Aftertreatment 1 Diesel Exhaust Fluid Return 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.
4376-6 3862-6 Aftertreatment 1 Diesel Exhaust Fluid Return Valve : Current Above Normal This code indicates that there is problem with the DEF pump reverting valve or the PETU wiring harness.
Follow the troubleshooting procedure to identify the root cause of the problem. Note: 372-5260 Test Kit is required for completing this procedure.
Illustration 1 g03171637Complete the procedure in the order in which the steps are listed.
Table 2
Troubleshooting Test Steps Values Results
1. Check for Opens in the PETU Wiring Harness for the Reverting 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 Diesel Exhaust Fluid Controller (DCU).
B. Disconnect the PETU wiring harness from the DEF pump and from the DCU.
C. Connect the 398-5063 Break-out Connector to the DCU connector. Connect the 398-5056 Break-out Connector to the DEF pump connector.
The connectors must be used to prevent damage to the DCU and DEF pump connector.
D. Measure the resistance between terminal 11 (reverting valve +) on the DEF pump connector and terminal 86 (reverting valve +) on the 86-pin DCU connector.
E. Measure the resistance between terminal 12 (reverting valve -) on the DEF pump connector and terminal 65 (reverting valve -) on the 86-pin DCU 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 problem is resolved. Proceed to Test Step 4.
2. Check for Short Circuits in the PETU Wiring Harness for the Reverting Valve
A. Turn the keyswitch to the OFF position.
B. Disconnect the PETU wiring harness from the DEF pump.
C. Disconnect the 86-pin connector from the DCU.
D. Connect the 398-5056 Break-out Connector to the DEF pump connector.
The connector must be used to prevent damage to the DEF pump connector.
E. Measure the resistance between terminal 11 (reverting valve +) on the DEF pump connector and a known good chassis ground.
F. Measure the resistance between terminal 12 (reverting valve -) on the DEF pump connector and a known good chassis ground.
100k 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 the wiring or replace the harness.
Verify that the problem is resolved. Proceed to Test Step 4.
3. Check for Short Circuits in the PETU Wiring Harness for the Reverting Valve
A. Turn the keyswitch to the OFF position.
B. Disconnect the PETU wiring harness from the DEF pump.
C. Disconnect the 86-pin connector from the DCU.
D. Connect the 398-5063 Break-out Connector to the DCU connector.
The 398-5063 Break-out Connector must be used to prevent damage to the DCU connector.
E. Measure the resistance between terminal 86 (reverting valve +) and all other pins in the 86-pin DCU harness connector.
F. Measure the resistance between terminal 65 (reverting valve -) and all other pins in the 86-pin DCU harness connector.
100k 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 the wiring or replace the harness.
Verify that the problem is resolved. Proceed to Test Step 4.
4. Perform a DEF Dosing System Verification Test
A. Turn the keyswitch to the ON position. Do not start the engine.
B. Connect to the "Diesel Exhaust Fluid Controller #1 ECM" in Cat ET.
C. Perform the "DEF Dosing System Verification Test" .
DEF Dosing System Verification Test
Result: The codes did not return.
Return the unit to service.