C7.1 Engines Caterpillar

DEF Pump Motor - Test

Usage:

C7.1 881

The Dosing Control Unit (DCU) monitors and controls the Diesel Exhaust Fluid (DEF) pump via voltages, current, and PWM signals.

The DCU sets a diagnostic trouble code if an error is detected in one or more of these parameters.

A -5 code indicates that the current flow through the circuit is low and there is an open in the circuit. A -6 code indicates that the current flow through the circuit is high and there is a short in the circuit. These codes can be activated only when the DCU is sending a command to the DEF pump.

Table 1 lists the diagnostic codes for the DEF pump circuit.

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Table 1
Diagnostic Trouble Codes for the DEF Pump
J1939 Code	CDL Code	Code Description (code descriptions may vary)	Comments
4374-5	3118-5	Aftertreatment #1 Diesel Exhaust Fluid Pump Motor Speed : Current Below Normal	This code indicates low current to the DEF pump speed sensor. The code is logged.
4374-6	3118-6	Aftertreatment #1 Diesel Exhaust Fluid Pump Motor Speed : Current Above Normal	This code indicates high current to the DEF pump speed sensor. The code is logged.
Follow the troubleshooting procedure in order to identify the root cause of the problem.

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Table 2
Required Tools
Tool	Part Number	Part Description	Qty
A	372-5260	Test Kit	1

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Illustration 1	g03811009
Schematic diagram for the DEF pump motor

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Illustration 2	g03811013
View of the pin locations for the DEF pump on the 86-pin DCU connector (24) DEF pump signal (26) DEF pump PWM return (46) DEF pump PWM supply

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Illustration 3	g03811015
Pin location on the DEF pump connector (8) PWM return (9) PWM supply (10) PWM signal

Complete the procedure in the order in which the steps are listed.

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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. Look for active or logged codes.	Diagnostic Trouble Codes	Result: There is an active or logged 4374-5, 3118-5, 4374-6 or 3118-6 diagnostic code. Proceed to Test Step 3.
3. Check for an Open Circuit in the Pump Electronic Tank Unit (PETU) Wiring Harness for the DEF Pump Motor Circuit A. Turn the keyswitch to the OFF position for 2 minutes to allow the DEF pump to purge, reset the code, and reset the DCU. B. Disconnect the PETU wiring harness from the DEF pump and the Diesel Exhaust Fluid Controller (DCU). C. Connect the 398-5063 Break-out Connector to the DCU connector. Connect the 398-5056 Break-out Connector to the pump connector. The connectors must be used to prevent damage to the DCU and pump connectors. D. Measure the resistance between terminal 9 (PWM +) on the DEF pump connector and terminal 46 (PWM +) on the 86 pin DCU connector. E. Measure the resistance between terminal 8 (PWM -) on the DEF pump connector and terminal 26 (PWM -) on the 86 pin DCU connector. F. Measure the resistance between terminal 10 (PWM SIGNAL) on the DEF pump connector and terminal 24 (PWM SIGNAL) on the 86 pin DCU connector.	Less than five Ohms	Result: All 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. Repair: There is an open circuit in the harness. Repair the wiring or replace the harness. Proceed to Test Step 6.
4. Check for Short Circuits in the PETU Wiring Harness for the DEF Pump Motor Circuit A. Turn the keyswitch to the OFF position. The keyswitch must be OFF for 2 minutes to allow the DEF pump to purge, reset the code, and reset the DCU. B. Disconnect the PETU wiring harness from the DEF pump and the DCU. C. Connect the 398-5063 Break-out Connector to the DCU connector. Connect the 398-5056 Break-out Connector to the pump connector. Note: The connectors must be used to prevent damage to the DCU and pump connectors. D. Measure the resistance between terminal 9 (PWM +) on the DEF pump connector and a known good chassis ground. E. Measure the resistance between terminal 8 (PWM -) on the DEF pump connector and a known good chassis ground. F. Measure the resistance between terminal 10 (PWM SIGNAL) on the DEF pump connector and a known good chassis ground.	Greater than 100k Ohms	Result: All 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. Repair: There is a short circuit in the harness. Repair the wiring or replace the harness. Proceed to Test Step 6.
5. Check for Short Circuits in the PETU Wiring Harness for the DEF Pump Motor Wiring A. Turn the keyswitch to the OFF position. The keyswitch must be OFF for 2 minutes to allow the DEF pump to purge, reset the code, and reset the DCU. B. Disconnect the PETU wiring harness from the DEF pump and the DCU. C. Connect the 398-5063 Break-out Connector to the DCU connector. Note: The 398-5063 Break-out Connector must be used to prevent damage to the DCU connector. D. Measure the resistance between terminal 46 (PWM +) and all other pins in the 86 pin DCU harness connector. E. Measure the resistance between terminal 26 (PWM -) and all other pins in the 86 pin DCU harness connector. F. Measure the resistance between terminal 24 (PWM SIGNAL) and all other pins in the 86 pin DCU harness connector.	Greater than 100k Ohms	Result: All resistance measurements are greater than 100k Ohms. Proceed to Test Step 6. Result: At least one of the resistance measurements is less than 100k Ohms. Repair: There is a short circuit in the harness. 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 to the "Diesel Exhaust Fluid Controller #1 ECM" using the electronic service tool. C. Perform the "DEF Dosing System Verification Test" .	Diagnostic codes	Result: The code did not return. Return the unit to service. Result: The code returned. Proceed to Test Step 7.
7. Replace the DEF Pump 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 DCU. B. Replace the DEF pump. Refer to Disassembly and Assembly, "Diesel Exhaust Fluid Pump - Remove and Install". C. Establish communication between the electronic service tool and the Diesel Exhaust Fluid Controller #1 ECM. D. Perform the "DEF Dosing System Verification Test".	Diagnostic Trouble Codes	Result: The code returned. Contact the Dealer Solutions Network (DSN). Result: The code did not return. Return the unit to service.