802977 Mercury CAP

Table 1
Diagnostic Codes Table for the DEF Tank Sensor
J1939 Code CDL Code Code Description
(code descriptions may vary) Comments
1761-3 3130-3 Aftertreatment 1 Diesel Exhaust Fluid Tank Level : Voltage Above Normal The ECM detects signal voltage that is not in the acceptable range.
The code is logged.
1761-4 3130-4 Aftertreatment 1 Diesel Exhaust Fluid Tank Level : Voltage Below Normal The ECM detects signal voltage that is not in the acceptable range.
The code is logged.
3031-3 3134-3 Aftertreatment 1 Diesel Exhaust Fluid Tank Temperature : Voltage Above Normal The ECM detects signal voltage that is not in the acceptable range.
The code is logged.
3031-4 3134-4 Aftertreatment 1 Diesel Exhaust Fluid Tank Temperature : Voltage Below Normal The ECM detects signal voltage that is not in the acceptable range.
The code is logged. The 5 VDC signal for the Diesel Exhaust Fluid (DEF) tank level sensor is routed to terminal 1 of the tank header unit. The 5 VDC 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 ECM provides short circuit protection for the internal power supply. A short circuit to the battery will not damage the internal power supply.Note: The tank header unit houses the DEF tank temperature and the DEF tank level sensors. The sensors are not serviceable individually.
Illustration 1 g03811036
Schematic diagram for the DEF tank header
Illustration 2 g03811042
(1) DEF level signal
(2) Sensor return
(3) DEF temperature signal 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 DEF Control Unit (DCU) . Refer to Troubleshooting, "Electronic Service Tools", if necessary.
B. Turn the keyswitch to the ON position.
C. Check for "-3" or " -4" active or logged codes.
Diagnostic code
Result: A -3 diagnostic code is active.
Proceed to Test Step 2.
Result: A -4 diagnostic code is active.
Proceed to Test Step 3.
2. Create a Short at the 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 sensor connector in order to create a short. Refer to Illustration 2.
C. Turn the keyswitch to the ON position.
D. Monitor the diagnostic codes on the electronic service tool. Check for an active -4 diagnostic code for the suspect sensor.
E. Turn the keyswitch to the OFF position.
Short created
Result: A -4 diagnostic code became active after creating the short at the sensor connector. The wiring is OK.
Repair: Replace the DEF tank header assembly. Refer to the Disassembly and Assembly manual.
Verify that the fault is resolved by cycling the keyswitch to the OFF position for 2 minutes. Turn to the keyswitch to the ON position and check for active codes.
Result: A -4 diagnostic code does not become active for the tank header unit.
Repair: Repair or replace the wiring harness.
Verify that the fault is resolved by cycling the keyswitch to the OFF position for 2 minutes. Turn to the keyswitch to the ON position and check for active codes.
If the fault is still present, contact the Dealer Solutions Network (DSN).
3. Create an Open at the Suspect Sensor Connector
A. Disconnect the connector for the tank header unit.
B. Turn the keyswitch to the ON position.
C. Monitor the diagnostic codes on the electronic service tool. Check for an active -3 diagnostic code for the suspect sensor.
D. Turn the keyswitch to the OFF position.
Create an open
Result: A -3 diagnostic code became active after disconnecting the sensor. The wiring is OK.
Repair: Replace the DEF tank header assembly. Refer to the Disassembly and Assembly manual.
Verify that the fault is resolved by cycling the keyswitch to the OFF position for 2 minutes. Turn to the keyswitch to the ON position and check for active codes.
Result: A -3 diagnostic code does not became active after disconnecting the sensor.
Repair: Repair or replace the wiring harness.
Verify that the fault is resolved by cycling the keyswitch to the OFF position for 2 minutes. Turn to the keyswitch to the ON position and check for active codes.
If the fault is still present, contact the Dealer Solutions Network (DSN).