853724 Mercury KNOB, Choke

Table 1
Diagnostic Trouble Codes for DEF Tank Level Is Low
J1939 Code Code Description Comments
1761-1 Aftertreatment #1 DEF Tank Volume #1 : Low - most severe (3) This code is a Level 3 inducement that becomes active when the DEF tank is empty. The engine is derated 100%, limited to low idle or 1000 RPM, and may experience 5 minute rolling shutdowns.
1761-17 Aftertreatment #1 DEF Tank Volume #1 : Low - least severe (1) This code is a Level 1 inducement that becomes active when the DEF level is critically low.
1761-18 Aftertreatment #1 DEF Tank Volume #1 : Low - moderate severity (2) This code is a Level 2 inducement that becomes active when the DEF level is critically low. Power loss may occur.
Follow the troubleshooting procedure to identify the root cause of the problem. Note: If active 1761 diagnostic codes are present, this may be due to an issue with the DEF pump which is causing a loss of prime. Operate the machine for several minutes and check to see if the DEF levels recover.Refer to Systems Operation, Testing and Adjusting, "DEF Dosing Control System" for details on inducement configuration options and inducement actions for specific tank levels.Note: Always turn the keyswitch to the OFF position before adding DEF to the tank.Complete the procedure in the order in which the steps are listed.
Table 2
Troubleshooting Test Steps Values Results
1. Check the DEF Level
A. Clean dirt and debris from around the cap before removing the cap.
B. Visually check the DEF level in the tank. If the DEF level is greater than 75%, proceed to Test Step 2. If the DEF level is less than 75%, continue with this procedure.
C. Turn the keyswitch to the ON position. Do not start the engine.
D. Wait for at least 1 minute. Check the current position of the DEF gauge.
E. Turn the keyswitch to the OFF position.
F. Clean dirt and debris from around the cap before removing the cap.
G. Fill the DEF tank to at least 25% capacity.
Note: Only use DEF that meets ISO 22241 quality standards.
H. Turn the keyswitch to the ON position.
I. Check for a change in the gauge position.
Gauge position
Result: The gauge did not move when DEF was added to the tank.
Proceed to Test Step 2.
Result: The gauge moved when DEF was added to the tank. Turn the keyswitch to the OFF position for 2 minutes to allow the DEF pump to purge, reset the code, and reset the Electronic Control Module (ECM).
Return the unit to service.
2. Check the Electrical Connection for the DEF Tank Header
A. Inspect the electrical connector to the DEF tank header. Refer to Troubleshooting, "Electrical Connectors - Inspect" for further information.
Look for corrosion or loose wires.
Electrical connections
Result: The electrical connectors are free of corrosion and are not loose.
Proceed to Test Step 3.
Result: The electrical connections are not free of corrosion and/or are loose.
Repair: Make the necessary repairs to the connectors. Turn the keyswitch to the OFF position for 2 minutes to allow the DEF pump to purge, reset the code, and reset the ECM.
Repeat the procedure from Test Step 1.
3. Inspect the DEF Tank Header
A. Turn the keyswitch to the OFF position.
B. Remove the DEF tank header (2) from the DEF tank. Refer to Disassembly and Assembly, "Manifold (DEF Heater) - Remove and Install".
C. If necessary, remove the filter sock from the DEF tank header.
D. Inspect the DEF tank header for a stuck float.
Correct operation of the float
Result: The float was not operating correctly.
Repair: If possible, repair the float and then install the filter sock. If the float cannot be repaired, replace the DEF tank header. Refer to Disassembly and Assembly, "Manifold (DEF Heater) - Remove and Install".
Return the unit to service.
Result: The float was operating correctly.
Repair: Install a replacement DEF tank header. Refer to Disassembly and Assembly, "Manifold (DEF Heater) - Remove and Install".
If the fault is still present, contact the Dealer Solutions Network (DSN).