C7.1 Engines Caterpillar


DEF Control Module Power - Test

Usage:

C7.1 881
This procedure covers the following diagnostic codes:

Table 1
Diagnostic Trouble Codes for the DEF Control Module Power Supply 
J1939 Code  CDL Code  Code Description
(code descriptions may vary) 
Comments 
3360-3  3820-3  Catalyst Tank Controller : Voltage Above Normal  The ECM detects voltage that is above the acceptable value.  
3360-4  3820-4  Catalyst Tank Controller : Voltage Below Normal  The ECM detects voltage that is below the acceptable value.  
5965-5  3838-5  Aftertreatment #1 Diesel Exhaust Fluid Dosing Control Unit Relay : Current Below Normal  The ECM detects current that is below the acceptable value 
5965-6  3838-6  Aftertreatment #1 Diesel Exhaust Fluid Dosing Control Unit Relay : Current Above Normal  The ECM detects current that is above the acceptable value 
5966-5  3965-5  Aftertreatment #1 Diesel Exhaust Fluid Dosing Control Unit : Current Below Normal  The ECM detects current that is below the acceptable value 
5966-6  3965-6  Aftertreatment #1 Diesel Exhaust Fluid Dosing Control Unit : Current Above Normal  The ECM detects current that is above the acceptable value 
6309-5  3966-5  Aftertreatment #1 Diesel Exhaust Fluid Dosing Control Unit (KSW sinking dout) : Current Below Normal  The ECM detects current that is below the acceptable value 
6309-6  3966-6  Aftertreatment #1 Diesel Exhaust Fluid Dosing Control Unit (KSW sinking dout) : Current Above Normal  The ECM detects current that is above the acceptable value 


Illustration 1g06134990
Schematic for the DCU and DEF quality sensor electrical power supply circuit


Illustration 2g03421149
Pin locations on the P1 connector for the power supply circuit
(2) DCU keyswitch
(3) DCU keyswitch
(5) DCU power relay signal
(15) DCU power relay return


Illustration 3g03155919
Pin locations on the DCU C2 connector for the power supply circuit
(1) Battery -
(2) Battery -
(3) Battery -
(4) Battery -
(5) Battery -
(6) Battery +
(7) Battery +
(8) Battery +
(9) Battery +
(52) Keyswitch

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

Table 2
Troubleshooting Test Steps  Value  Results 

1. Inspect Electrical Connectors and Wiring

A. Ensure that the battery disconnect switch is in the OFF position.

B. Thoroughly inspect all connectors associated with the DEF control module power supply.

C. Check all fuses.

D. Perform a 45 N (10 lb) pull test on each of the wires in the connectors associated with the power supply.

E. Check all the wiring associated with the electrical power supplies for abrasions and pinch points.
 

Damaged wire or connector. Blown fuse.
 

Result: A damaged wire or damaged connector was not found. The fuses are OK.

Proceed to Test Step 2.

Result: A damaged wire or damaged connector was found. A blown fuse was found.

Repair: Repair the damaged wire or the damaged connector. Replace all blown fuses.

Use the electronic service tool to clear all logged diagnostic codes. Verify that the repair eliminates the fault.
 

2. Check for Active Diagnostic Codes

A. Establish communication between the electronic service tool and the ECM. Refer to Troubleshooting, "Electronic Service Tools", if necessary.

B. Check the "Active Diagnostics" screen on the electronic service tool.
 

Diagnostic code
 

Result: A 3360-X or 3820-X diagnostic code is active.

Proceed to Table 3, "Troubleshooting Procedure for the DCU Power Supply".

Result: There is a problem with the power supply to the DEF quality sensor.

Proceed to Table 3, "Troubleshooting Procedure for the DCU Power Supply" - Test Step 7.

Result: A 5965-5 or 3838-5 diagnostic code is active.

Proceed to Table 4, "Troubleshooting for the Main DCU Power Relay" - Test Step 1.

Result: A 5965-6 or 3838-6 diagnostic code is active.

Proceed to Table 4, "Troubleshooting for the Main DCU Power Relay" - Test Step 4.

Result: A 5966-5, 3965-5, 6309-5 or 3966-5 diagnostic code is active.

Proceed to Table 5, "Troubleshooting Procedure for the DCU Keyswitch Signal" - Test Step 1.

Result: A 5966-6, 3965-6, 6309-6 or 3966-6 diagnostic code is active.

Proceed to Table 5, "Troubleshooting Procedure for the DCU Keyswitch Signal" - Test Step 4.
 

Table 3
Troubleshooting Procedure for the DCU Power Supply 
Troubleshooting Test Steps  Value  Results 

1. Check the Voltage at the PETU Power Connector

A. Disconnect the PETU power connector.

B. Use a suitable multimeter to take the following voltage measurements at the PETU power connector (application side).

Terminal 1 to terminal 3
Terminal 2 to terminal 4
 

Battery voltage
 

Result: The measured voltage is equal to battery voltage.

Reconnect the PETU power connector. Proceed to Test Step 2.

Result: The measured voltage is not equal to battery voltage.

Repair: Replace the wiring between the battery and the PETU power connector.

Use the electronic service tool to clear all logged diagnostic codes and verify that the repair eliminates the fault.
 

2. Check the Voltage to the DCU Power Relay

A. Disconnect the main DCU power relay.

B. Measure the voltage between terminal 1 on the harness connector for the relay and a suitable ground.
 

Battery voltage
 

Result: The measured voltage is equal to battery voltage.

Reconnect the DCU power relay. Proceed to Test step 3.

Result: The measured voltage is not equal to battery voltage.

Repair: Replace the wiring between the PETU power connector and the DCU power relay.

Use the electronic service tool to clear all logged diagnostic codes and verify that the repair eliminates the fault.
 

3. Check the Voltage to the VLPM

A. Disconnect the VLPM.

B. Turn the keyswitch to the ON position. Do not attempt to start the engine.

C. Measure the voltage between terminal 1 on the harness connector for the VLPM and suitable ground.

D. Turn the keyswitch to the OFF position.
 

Battery voltage
 

Result: The measured voltage is equal to battery voltage.

Reconnect the VLPM. Proceed to Test Step 5.

Result: The measured voltage is not equal to battery voltage.

Proceed to Test Step 4.
 

4. Check the Wiring Between the DCU Power Relay and the VLPM

A. Disconnect the DCU power relay.

B. Measure the resistance between Terminal 4 on the harness connector for the relay and terminal 1 on the harness connector for the VLPM. 

Less than 2.0 Ohms
 

Result: The resistance is less than 2.0 Ohms.

Repair: Install a replacement DCU power relay.

Use the electronic service tool to clear all logged diagnostic codes and verify that the repair eliminates the fault.

Result: The resistance is greater than 2.0 Ohms.

Repair: Replace the wiring between the DCU power relay and the VLPM.

Use the electronic service tool to clear all logged diagnostic codes and verify that the repair eliminates the fault.
 

5. Check the Voltage at the DCU Connector

A. Disconnect the 53-pin DCU connector.

B. Turn the keyswitch to the ON position.

C. Use a suitable multimeter to measure the voltage between the following terminals on the harness connector for the DCU:

Terminal 1 and terminal 6
Terminal 2 and terminal 7
Terminal 3 and terminal 8
Terminal 4 and terminal 9
Terminal 5 and terminal 9

D. Turn the keyswitch to the OFF position.
 

Battery voltage
 

Result: The measured voltage is equal to battery voltage.

Contact the Dealer Solutions Network (DSN).

Result: The measured voltage is not equal to battery voltage.

Proceed to Test Step 6.
 

6. Check the Wiring Between the VLPM and the DCU

A. Disconnect the VLPM.

B. Use a suitable multimeter to measure the resistance between terminal 2 on the harness connector for the VLPM and the following terminals:

C2:6
C2:7
C2:8
C2:9

C. Use a suitable multimeter to measure the resistance between terminal 3 on the harness connector for the VLPM and the following terminals:

C2:1
C2:2
C2:3
C2:4
C2:5
 

Less than 2.0 Ohms
 

Result: The resistance is less than 2.0 Ohms.

Repair: Install a replacement VLPM.
Use the electronic service tool to clear all logged diagnostic codes and verify that the repair eliminates the fault.

Result: The resistance is greater than 2.0 Ohms.

Repair: Replace the wiring between the VLPM and the DCU.

Use the electronic service tool to clear all logged diagnostic codes and verify that the repair eliminates the fault.
 

7. Check the Wiring Between the VLPM and the DEF Quality Sensor

A. Disconnect the VLPM and the DEF tank header connector.

B. Use a suitable multimeter to measure the resistance between terminal 2 on the VLPM harness connector and terminal 3 on the DEF tank header connector.

C. Use a suitable multimeter to measure the resistance between terminal 3 on the VLPM harness connector and terminal 4 on the DEF tank header connector.
 

Less than 2.0 Ohms
 

Result: The resistance is less than 2.0 Ohms.

Repair: Install a replacement VLPM.
Use the electronic service tool to clear all logged diagnostic codes and verify that the repair eliminates the fault.

Result: The resistance is greater than 2.0 Ohms.

Repair: Replace the wiring between the VLPM and the DEF tank header connector.

Verify that the repair eliminates the fault.
 

Table 4
Troubleshooting Procedure for the Main DCU Power Relay 
Troubleshooting Test Steps  Value  Results 

1. Create a Short Circuit at the DCU Power Relay Connector

A. Turn the keyswitch to the OFF position.

B. Disconnect the DCU power relay.

C. Fabricate a jumper wire. Install the jumper wire between terminal 2 and terminal 5 on the harness connector for the relay.

D. Turn the keyswitch to the ON position.

E. Use the electronic service tool to check for active diagnostic codes. Look for an active 5965-6 or 3838-6 diagnostic code.

F. Turn the keyswitch to the OFF position.
 

Diagnostic codes
 

Result: A 5965-6 or 3838-6 diagnostic code is active with the jumper installed.

Repair: Install a replacement DCU power relay.

Use the electronic service tool to clear all logged diagnostic codes and verify that the repair eliminates the fault.

Result: The 5965-5 or 3838-5 diagnostic code is still active with the jumper installed.

Proceed to Test Step 2.
 

2. Check the Wiring Between the DCU Power Relay and the PETU 12-Pin Connector

A. Disconnect the main DCU power relay. Disconnect the PETU 12-pin connector.

B. Measure the resistance between terminal 2 on the harness connector for the relay and terminal 12 on the 12-pin connector.

C. Measure the resistance between terminal 5 on the harness connector for the relay and terminal 11 on the 12-pin connector. 

Less than 2.0 Ohms.
 

Result: Both the resistance measurements are less than 2.0 Ohms.

Proceed to Test Step 3.

Result: At least one of the resistance measurements is greater than 2.0 Ohms.

Repair: Replace the wiring between the DCU power relay and the PETU 12-pin connector.

Use the electronic service tool to clear all logged diagnostic codes and verify that the repair eliminates the fault.
 

3. Check the Wiring Between the PETU 12-Pin Connector and the ECM

A. Disconnect the main DCU power relay. Disconnect the P1 connector from the ECM.

B. Measure the resistance between terminal 12 on the 12-pin connector and P1:5.

C. Measure the resistance between terminal 11 on the 12-pin connector and P1:15. 

Less than 2.0 Ohms 

Result: Both the resistance measurements are less than 2.0 Ohms.

Contact the Dealer Solutions Network (DSN).

Result: At least one of the resistance measurements is greater than 2.0 Ohms.

Repair: Replace the wiring between the PETU 12-pin connector and the P1 connector.

Use the electronic service tool to clear all logged diagnostic codes and verify that the repair eliminates the fault.
 

4. Create an Open Circuit at the DCU Power Relay

A. Turn the keyswitch to the OFF position.

B. Disconnect the DCU power relay.

C. Turn the keyswitch to the ON position. Do not attempt to start the engine.

D. Use the electronic service tool to check for active diagnostic codes. Look for an active 5965-5 or 3838-5 diagnostic code.

E. Turn the keyswitch to the OFF position.
 

Diagnostic codes 

Result: A 5965-5 or 3838-5 diagnostic code is active with the relay disconnected.

Repair: Install a replacement DCU power relay.

Use the electronic service tool to clear all logged diagnostic codes and verify that the repair eliminates the fault.

Result: The 5965-6 or 3838-6 diagnostic code is still active with the relay disconnected.

Proceed to Test Step 5.
 

5. Check the Wiring between the PETU 12-pin connector and the ECM for a Short Circuit

A. Disconnect the P1 connector from the ECM. Disconnect the PETU 12-pin connector.

B. Measure the resistance between P1:5 and all other terminals on the P1 connector.

C. Measure the resistance between P1:15 and all other terminals on the P1 connector.
 

Greater than 100 Ohms
 

Result: All resistance measurements are greater than 100 Ohms.

Proceed to Test Step 6.

Result: At least one of the resistance measurements is less than 100 Ohms.

Repair: Replace the wiring between the PETU 12-pin connector and the ECM.

Use the electronic service tool to clear all logged diagnostic codes and verify that the repair eliminates the fault.
 
6. Check the Wiring between the PETU 12-pin connector and the Main DCU Power Relay for a Short Circuit

A. Reconnect the PETU 12-pin connector.

B. Measure the resistance between P1:5 and all other terminals on the P1 connector.

C. Measure the resistance between P1:15 and all other terminals on the P1 connector.
 

Greater than 100 Ohms
 

Result: All resistance measurements are greater than 100 Ohms.

Contact the Dealer Solutions Network (DSN).

Result: At least one of the resistance measurements is less than 100 Ohms.

Repair: Replace the wiring between the PETU 12-pin connector and the main DCU power relay.

Use the electronic service tool to clear all logged diagnostic codes and verify that the repair eliminates the fault.
 

Table 5
Troubleshooting Procedure for the DCU Keyswitch Signal 
Troubleshooting Test Steps  Value  Results 

1. Create a Short Circuit at the DCU Connector

A. Turn the keyswitch to the OFF position.

B. Disconnect the 53-pin DCU connector.

C. Fabricate a jumper wire. Install the jumper wire between C2:52 and a suitable ground.

D. Turn the keyswitch to the ON position. Do not attempt to start the engine.

E. Use the electronic service tool to check for active diagnostic codes.

Note: Other diagnostic codes will be active with the DCU connector disconnected. Disregard all other codes and only look for diagnostic codes that relate to the DCU keyswitch.

F. Turn the keyswitch to the OFF position.
 

Diagnostic codes
 

Result: A 5966-6, 3965-6, 6309-6 or 3966-6 diagnostic code is active with the jumper installed.

Contact the Dealer Solutions Network (DSN).

Result: The 5966-5, 3965-5, 6309-5 or 3966-5 diagnostic code is still active with the jumper installed.

Remove the jumper wire. Reconnect the DCU connector. Proceed to Test Step 2.
 

2. Create a Short Circuit at the 12-Pin PETU Connector

A. Disconnect the 12-pin PETU connector.

B. Fabricate a jumper wire. Install the jumper wire between terminal 5 on the 12-pin connector (application side) and a suitable ground.

C. Turn the keyswitch to the ON position.

D. Use the electronic service tool to check for active diagnostic codes.

Note: Other diagnostic codes will be active with the DCU connector disconnected. Disregard all other codes and only look for diagnostic codes that relate to the DCU keyswitch.

E. Turn the keyswitch to the OFF position.
 

Diagnostic codes 

Result: A 5966-6, 3965-6, 6309-6 or 3966-6 diagnostic code is active with the jumper installed.

Repair: Replace the wiring between the 12-pin PETU connector and the DCU.

Use the electronic service tool to clear all logged diagnostic codes and verify that the repair eliminates the fault.

Remove the jumper wire. Proceed to Test Step 3. 

3. Check the Wiring for an Open Circuit

A. Disconnect the P1 connector from the ECM.

B.Measure the resistance between terminal 5 on the 12-pin PETU connector (application side) and P1:2.

C.Measure the resistance between terminal 5 on the 12-pin PETU connector (application side) and P1:3.
 

Less than 2.0 Ohms
 

Result: The resistance measurements are less than 2.0 Ohms.

Contact the Dealer Solutions Network (DSN).

Result: At least one of the resistance measurements is greater than 2.0 Ohms.

Repair: Replace the wiring between the 12-pin PETU connector and the ECM.
 

4. Create an Open Circuit at the DCU Connector

A. Turn the keyswitch to the OFF position.

B. Disconnect the 53-pin DCU connector.

C. Turn the keyswitch to the ON position.

D. Use the electronic service tool to check for active diagnostic codes.

Note: Other diagnostic codes will be active with the DCU connector disconnected. Disregard all other codes and only look for diagnostic codes that relate to the DCU keyswitch.

E. Turn the keyswitch to the OFF position.
 

Diagnostic codes
 

Result: A 5966-5, 3965-5, 6309-5 or 3966-5 diagnostic code is active with the DCU disconnected.
Contact the Dealer Solutions Network (DSN).

Result: The 5966-6, 3965-6, 6309-6 or 3966-6 diagnostic code is still active with the DCU disconnected.

Reconnect the 53-pin DCU connector. Proceed to Test Step 5.
 

5. Create an Open Circuit at the 12-Pin PETU Connector

A. Disconnect the 12-pin PETU connector.

B. Turn the keyswitch to the ON position.

C. Use the electronic service tool to check for active diagnostic codes.

Note: Other diagnostic codes will be active with the DCU connector disconnected. Disregard all other codes and only look for diagnostic codes that relate to the DCU keyswitch.

D. Turn the keyswitch to the OFF position.
 

Diagnostic codes
 

Result: A 5966-5, 3965-5, 6309-5 or 3966-5 diagnostic code is active with the connector disconnected.

Repair: Replace the wiring between the DCU and the 12-pin PETU connector.

Use the electronic service tool to clear all logged diagnostic codes and verify that the repair eliminates the fault.

Result: The 5966-6, 3965-6, 6309-6 or 3966-6 diagnostic code is still active with the connector disconnected.

Proceed to Test Step 6.
 

6. Check the Wiring for a Short Circuit

A. Disconnect the P1 connector from the ECM.

B. Measure the resistance between P1:2 and all other terminals on the P1 connector except P1:3.

C. Measure the resistance between P1:3 and all other terminals on the P1 connector apart from P1:2.
 

Greater than 100 Ohms
 

Result: All resistance measurements are greater than 100 Ohms.

Contact the Dealer Solutions Network (DSN).

Result: At least one of the resistance measurements is less than 100 Ohms.

Repair: Replace the wiring between the 12-pin DCU connector and the ECM.

Use the electronic service tool to clear all logged diagnostic codes and verify that the repair eliminates the fault.
 

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