LOCK 4H9648 - Caterpillar

Use this procedure to troubleshoot the electrical system if a problem is suspected with the sensors. Use this procedure if any of the diagnostic codes in Table 1 are active or easily repeated.
Table 1
J1939 Code and Description CDL Code and Description Comments
1761-3
Aftertreatment #1 DEF Tank Volume : Voltage Above Normal 3130-3
Aftertreatment #1 DEF Tank #1 Level Sensor : Voltage Above Normal The ECM detects signal voltage that is not in the acceptable range.
The code is logged.
1761-4
Aftertreatment #1 DEF Tank Volume : Voltage Below Normal 3130-4
Aftertreatment #1 DEF Tank #1 Level Sensor : Voltage Below Normal The ECM detects signal voltage that is not in the acceptable range.
The code is logged. Diagnostics on the Caterpillar Electronic Technician (ET)
Illustration 1 g03702189
Not all connectors are shown, refer to the appropriate schematic
Probable Causes
Codes
Sensor
Sensor connectorRecommended Actions
Table 2
Troubleshooting Test Steps Values Results
1. Check for Codes
A. Establish communication between Cat® Electronic Technician (ET) and the Diesel Exhaust Fluid Controller (DCU) .
B. Turn the keyswitch to the ON position.
C. Look 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 signal and return wire at the sensor connector in order to create a short.
C. Turn the keyswitch to the ON position.
D. Monitor the diagnostic codes on Cat ET. Check for an active -4 diagnostic code for the level 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 level sensor. Refer to the Disassembly and Assembly manual.
Verify that