98AJ-4-0105 Tohatsu AIR HOSE

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 Return Valve : Current Below Normal     This code indicates 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 there is problem with the DEF pump reverting valve or the PETU wiring harness.    
Follow the troubleshooting procedure in order to identify the root cause of the problem.    
Table 2
Required Tools    
Tool     Part Number     Part Description     Qty    
A     372-5260     Test Kit     1    
Illustration 1 g03811027
Schematic diagram for the DEF return valve circuit
Illustration 2 g03417162
View of the pin locations for the DEF return valve on the 86-pin DCU connector (65) DEF pump reversing valve return (86) DEF pump reversing valve supply
Illustration 3 g03417188
Pin locations for the DEF return valve on the DEF pump connector (11) Reversing valve supply (12) Reversing valve returnComplete 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. Inspect the 86-pin DCU 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 DCU connector and the connector for the DEF pump.
D. 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.
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. Download the "Warranty Report" from the engine ECM before performing any troubleshooting or clearing diagnostic trouble codes.
C. Establish communication between the electronic service tool and the Dosing Control Unit (DCU) .
D. Check for active or logged codes.
   
Diagnostic trouble codes
   
Result: There is an active or logged 4376-5, 3862-5, 4376-6 or 3862-6 diagnostic code.
Proceed to Test Step 3.
Result: None of the preceding diagnostic codes are active or recently logged.
Proceed to Test Step 6.
   
3. Check for an Open Circuit in the PETU 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 Diesel Exhaust Fluid Controller (DCU).
B. Disconnect the PETU wiring harness from the DEF pump and from the DCU.
C. Connect the 398-5062 Break-out Connector to the DCU connector. Connect the 398-5056 Break-out Connector to the DEF pump connector.
Note: The connectors must be used to prevent damage to the DCU and DEF pump connector.
D. Measure the resistance between terminal 11 (return valve +) on the DEF pump connector and terminal 86 (return valve +) on the 86 pin DCU connector.
E. Measure the resistance between terminal 12 (return valve -) on the DEF pump connector and terminal 65 (return valve -) on the 86 pin DCU connector.
   
Less than five Ohms
   
Result: Both resistance measurements are less than five Ohms.
Proceed to Test Step 4.
Result: At least one of the resistance measurements is greater than five 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 PETU Wiring Harness for the return 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.
Note: The connector 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 PETU Wiring Harness for the return 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 398-5062 Break-out Connector to the DCU connector.
Note: The 398-5062 Break-out Connector must be used to prevent damage to the DCU connector.
E. Measure the resistance between terminal 86 (return valve +) and all other pins in the 86 pin DCU harness connector.
F. Measure the resistance between terminal 65 (return valve -) and all other pins in the 86 pin DCU harness 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.
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