WASHER-RETAINING 7N1066 - 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 Table 1 is active or easily repeated.
Table 1
Diagnostic Codes Table    
Code and Description    Conditions which Generate this Code    System Response    
96-3 Fuel Level Sensor voltage above normal     The voltage on the signal wire for the fuel level sensor is above normal.     The code is logged.    
96-4 Fuel Level Sensor voltage below normal     The voltage on the signal wire for the fuel level sensor is below normal.    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 sensor's variable resistance affects the pull-up voltage that is created by the ECM. When the sensor's resistance is low, the pull-up voltage is low. When the sensor's resistance is high, the pull-up voltage is high. Refer to Table 2.
Table 2
Relationship Between the Sensor's 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 sensorTest Step 1. Verify that the "Fuel Level Sensor Installation Status" Parameter is Programmed Correctly
Remove electrical power from the ECM.
Connect the Caterpillar Electronic Technician (ET) to the service tool connector.
Restore electrical power to the ECM.
Establish communication with the ECM.
Verify that the "Fuel Level Sensor Installation Status" parameter is programmed to "Installed".
Remove electrical power from the ECM.Expected Result:The "Fuel Level Sensor Installation Status" parameter is programmed to "Installed".Results:
OK - The "Fuel Level Sensor Installation Status" parameter is programmed correctly. Proceed to Test Step 2.
Not OK - The "Fuel Level Sensor Installation Status" parameter is programmed to "Not Installed".Repair: Program the "Fuel Level Sensor Installation Status" parameter to "Installed".Verify that the repair eliminates the problem.STOPTest Step 2. Inspect the Electrical Connectors and the Wiring
Remove the electrical power from the ECM.
Illustration 2 g01379047
Location of the ECM connectors that are for the fuel level sensor (back engine view) (1) J1/P1 ECM connectors (2) Connector for the fuel level sensor
Thoroughly inspect connectors (1) and (2). Refer to Troubleshooting, "Electrical Connectors-Inspect" for details.
Illustration 3 g01379069
Terminal locations at the P1 ECM connectors that are associated with the fuel level