3508, 3508B, 3508C, 3512, 3512B, 3512C, 3516, 3516B and 3516C Engines Caterpillar Monitoring System Caterpillar

Illustration 1	g00573573
Schematic For Fuel Level Switch

Note: Ensure that the desired diagnostic code (CID FMI) is on hold. Ensure that the "SERV CODE" indicator is ON. Use the electrical system schematic for the engine that is being serviced to find the connector contact on the Main Display Module that corresponds to the CID in the Display Area.

This diagnostic code is recorded when the Main Display Module reads the signal voltage of the switch as being too high. The corresponding Indicator Lamp flashes as a result of this diagnostic condition. The following examples are possible causes.

• The fuel level switch has a problem.

• The fuel level switch unit ground circuit in the engine harness is open.

• The fuel level switch unit signal in the engine harness is shorted to +battery.

• The fuel level switch unit signal circuit in the engine harness is open or the connector is disconnected.

• The Main Display Module has a problem.

• The fuel level switch is not used. The jumper for the fuel level switch is not installed on the customer connector.

1. Check the Display Area and the Harness.

   1. Turn the "ECS" switch to the OFF/RESET position.

   2. Check for loose terminal connections or corroded terminal connections to the fuel level switch.

   3. Clean corroded terminals and tighten loose connections.

   4. Turn the "ECS" switch to the COOLDOWN/STOP position. The "SERV CODE" indicator should be ON for the diagnostic code CID 0096 FMI 03.

   5. Disconnect the engine harness fuel level switch signal wire and observe the "SERV CODE" indicator that is in the Display Area.

      Expected Result: The "Serv Code" indicator should turn OFF.

      Results:

      • OK - The "SERV CODE" indicator turns OFF. The Fuel Level Switch has a problem. Replace the Fuel Level Switch Unit.

      • Not OK - The "SERV CODE" indicator stays ON. The harness wiring or the Main Display Module has a problem. Proceed to Step 2.

2. Check for an Open Ground Wire.

   1. Turn the "ECS" switch to the OFF/RESETposition.

   2. Measure the resistance between the battery ground and the ground wire for the fuel level switch unit.

      Expected Result: The resistance should be less than 5 ohms.

      Results:

      • OK - The resistance is less than 5 ohms. Proceed to Step 3.

      • Not OK - The resistance is greater than 5 ohms or equal to 5 ohms. The ground wire for the harness is open. Repair the ground wire of the harness or replace the ground wire of the harness for the Fuel Level Switch Unit.

3. Measure the Voltage of the Fuel Level Switch Signal Wire.

   1. Turn the "ECS" switch to the OFF/RESET position.

   2. Measure the voltage from the ground to the Fuel Level Switch Unit Signal Wire.

      Expected Result: The voltage should be 6.0 ± 0.5 DCV.

      Results:

      • OK - The voltage is 6.0 ± 0.5 DCV. If the SERV CODE indicator remains ON, repeat Step 1, Step 2 and Step 3. If the cause of the diagnostic fault is not found, replace the Main Display Module.

      • Not OK - The voltage is less than 6.0 ± 0.5 DCV. The harness wiring has a problem. There is an open circuit or a short to ground in the Fuel Level Switch Signal Wire or a poor connection. Repair the harness or replace the harness. If the cause of the diagnostic fault is not found, replace the Main Display Module.

      • Not OK - The voltage is greater than 6.0 ± 0.5 DCV or the voltage is less than 0.5 DCV. The harness is shorted to a power circuit. Repair the harness or replace the harness. If the cause of the diagnostic fault is not found, replace the Main Display Module.