Fitting 4C7156 - Caterpillar

System Operation Description:The fuel level sensor is a component that is installed by the customer. The sensor is a passive sensor. The sensor does not require an operating voltage from the Electronic Control Module (ECM).Use this procedure to troubleshoot the electrical system if a problem is suspected with the fuel level sensor or if any one of the diagnostic codes in the table is active or easily repeated.
Table 1
J1939 Code and Description CDL Code and Description System Response
96-3
Fuel Level : Voltage Above Normal 96-3
Fuel Level Sensor : Voltage Above Normal The code is logged.
96-4
Fuel Level : Voltage Below Normal 96-4
Fuel Level Sensor : Voltage Below Normal
96-17
Fuel Level : Low - least severe (1) N/A Add fuel to the fuel tank. Refer to the literature that is provided by the OEM of the vessel for the correct procedure. When the fuel tank is full, the fuel level sensor has a resistance of 33 Ohms. When the fuel tank is empty, the fuel level sensor has a resistance of 240 Ohms. The resistance from the fuel level sensor varies between these values as the fuel level varies.The sensors variable resistance affects the pull-up voltage that is created by the ECM. When the sensors resistance is low, the pull-up voltage is low. When the sensors resistance is high, the pull-up voltage is high. Refer to Table 2.
Table 2
Relationship Between the Sensors Resistance and the Voltage on the Signal Wire
Fuel Level Resistance Approximate Voltage on the Signal Wire
Full 33 Ohms 0.15 VDC
Empty 240 Ohms 1.8 VDC The most likely electrical problem with the circuit for the fuel level sensor is a problem in the wiring harness. The next likely cause is a problem with the fuel level sensor. The least likely cause is a problem with the ECM.
Illustration 1 g01379074
Schematic of the circuit that is for the fuel level sensor
Table 3
Troubleshooting Test Steps Values Results
1. Verify that the "Fuel Level Sensor Installation Status" Parameter is Programmed Correctly
A. Remove electrical power from the ECM.
B. Connect the Cat Electronic Technician (ET) to the service tool connector.
C. Restore electrical power to the ECM.
D. Establish communication with the ECM.
E. Verify that the "Fuel Level Sensor Installation Status" parameter is programmed to "Installed".
F. Remove electrical power from the ECM.
Parameter
Result: The "Fuel Level Sensor Installation Status" parameter is programmed correctly. Proceed to Test Step 2.
Result: The "Fuel Level Sensor Installation Status" parameter is programmed to "Not Installed".
Program the "Fuel Level Sensor Installation Status" parameter to "Installed". Verify that the repair eliminates the problem.
STOP
2. Inspect the Electrical Connectors and the Wiring
A. Remove the electrical power from the ECM.
B. Thoroughly inspect connectors (1) and (2). Refer to Troubleshooting, "Electrical Connectors-Inspect", for details.
C. Perform a 45 N (10 lb) pull test on each of the wires that are associated with the fuel level sensor.
D. Check the allen head screw on each of the ECM connectors for the proper torque. Refer to Troubleshooting, "Electrical Connectors - Inspect", for the correct torque values.
E. Check the harness and the wiring for abrasion and for pinch