HOSE AS 8X6171 - Caterpillar

Battery voltage is routed to terminal 4 of the tank header unit. The return is routed to terminal 3 of the tank header unit. The temperature and level signals are routed through the CAN C data link on terminal 2 (CAN C+) and terminal 1 (CAN C-). The ECM provides short circuit protection for the internal power supply. A short circuit to the battery will not damage the internal power supply.
Illustration 1 g03708685
Schematic for the DEF tank header unit
Illustration 2 g03700612
(1) DEF tank header electrical connector
(2) DEF tank headerIf possible, the machine should be on a level surface before the following procedure is performed.The tank header unit houses the DEF tank temperature and the DEF tank level sensors. From 2017 onwards, the tank header unit also houses a DEF quality sensor. The sensors are not serviceable individually.Complete the procedure in the order in which the steps are listed.
Table 2
Troubleshooting Test Steps Values Results
1. Check for Diagnostic Codes
A. Establish communication between the electronic service tool and the Diesel Exhaust Fluid Controller (DCU) . Refer to Troubleshooting, "Electronic Service Tools", if necessary.
B. Turn the keyswitch to the ON position.
C. Look for active or logged codes.
Diagnostic code
Result: A -12 diagnostic code is active.
Proceed to Test Step 2.
Result: A 1761-2 (3130-2) code is active.
Proceed to Test Step 4.
Result: A 3516-2 (3100-2) code is active.
Proceed to Test Step 5.
2. Check for Battery Voltage at the DEF Tank Header
A. Disconnect the harness at the DEF tank header.
B. Turn the keyswitch to the ON position.
C. Measure the voltage between terminals 3 and 4.
D. Turn the keyswitch to the OFF position.
Battery voltage
Result: The measured voltage is not equal to battery voltage.
Repair: Investigate the cause of the incorrect voltage. Refer to Troubleshooting, "Electrical Power Supply - Test".
Result: The measured voltage is equal to battery voltage.
Proceed to Test Step 3.
3. Connect a Replacement DEF Tank Header Unit
A. Disconnect the connector from the DEF tank header unit.
B. Connect a replacement DEF tank header unit to the harness. Do not install the unit.
C. Connect the electronic service tool.
D. Turn the keyswitch to the ON position. Wait for at least 2 minutes.
E. Check for -12 codes.
DEF tank header replacement
Result: No -12 diagnostic codes are active.
Repair: Install the replacement DEF tank header unit.
Confirm that the fault has been eliminated.
Result: A -12 diagnostic code is active.
Reconnect the harness connector to the original DEF tank header unit.
Contact the Dealer Solutions Network (DSN).
4. Ensure that the Application is on a Level Gradient
A. If necessary, move the application to a level gradient.
B. Wait at least 2 minutes. Turn the keyswitch to the ON position.
C. Connect to the electronic service tool.
D. Use the electronic service tool to check the DEF level measurement.
Note: Use the electronic service tool for this step and not a gauge on the application.
DEF Level
Result: The DEF level indicates a value between 0 percent and 100 percent.
Return the engine to service.
Result: The DEF level indicates "Conditions Not Met" 2 minutes after the application has been moved to a level gradient.
Proceed to Test Step 5.
5. Flush the