BUTTON 3524534 - Caterpillar

The 5 V signal for the Diesel Exhaust Fluid (DEF) tank level sensor is routed to terminal 1 of the tank header unit. The 5 V signal for the DEF tank temperature sensor is routed to terminal 3 of the tank header unit. The sensor return is shared and is routed to terminal 2 of the tank header unit. The Electronic Control Module (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 g06100987
Illustration 2 g06101034
The DEF pumps are on the front side of the Pump Electronic Tank Unit (PETU).
(1) Aftertreatment #1 DEF pump 1
(2) Aftertreatment #1 DEF pump 2
(3) Aftertreatment #2 DEF pump 1
(4) Aftertreatment #2 DEF pump 2
(5) DEF header for Aftertreatment #1 pump 1 system
(6) DEF header for Aftertreatment #1 pump 2 system
(7) DEF header for Aftertreatment #2 pump 2 system
(8) DEF header for Aftertreatment #1 pump 1 system
Table 2
Troubleshooting Test Steps Values Results
1. Check for Codes
A. Connect Cat® Electronic Technician (ET) to the service tool connector.
B. Select the Diesel Exhaust Fluid Controller (DCU).
C. Determine if a code is active or logged.
Codes
Result: A -3 code is active or logged.
Proceed to Test Step 2.
Result: A -4 code is active or logged.
Proceed to Test Step 3.
2. Create a Short at the Affected Sensor Connector
A. Verify that the harness connector is free of debris, free of corrosion and securely connected.
B. Install a jumper wire between the appropriate signal and return wire at the affected sensor connector to create a short.
C. Turn the keyswitch to ON.
D. Connect Cat ET.
E. Use Cat ET to monitor the following codes:
- -4 code
F. Turn the keyswitch to OFF.
Create a Short
Result: A -4 code becomes active.
Repair: The wiring is OK. Replace the affected DEF tank header assembly. Refer to the Disassembly and Assembly manual for additional information.
Result: A -4 code does not become active.
Repair: Repair or replace the wiring harness.
If the problem is not resolved, proceed to Test Step 3.
3. Create an Open at the Affected Sensor Connector
A. Disconnect the connector of the affected tank header unit.
B. Turn the keyswitch to ON.
C. Connect Cat ET.
D. Use Cat ET to monitor the following codes:
- -3 code
E. Turn the keyswitch to OFF.
Create an Open
Result: A -3 code becomes active.
Repair: The wiring is OK. Replace the affected DEF tank header assembly. Refer to the Disassembly and Assembly manual for additional information.
Verify that the repair eliminated the problem.
Result: A -3 code does not become active.
Repair: Repair or replace the wiring harness.
Verify that the repair eliminated the problem.
If the procedure did not correct the issue, contact your Cat dealer Technical Communicator (TC). For further assistance, your TC can confer with the Dealer Solutions Network (DSN).