P2066

P2066-FUEL LEVEL SENSOR 2 PERFORMANCE





For a complete wiring diagram, refer to the Wiring Information.

Theory of Operation

The Fuel Level Sensor information is a bussed message to the Powertrain Control Module (PCM) from the Body Control Module (BCM). The fuel level rationality will set a fault for a fuel level reading that does not change over an accumulated mileage threshold to keep stuck high or stuck low fuel levels from disabling OBD monitors. If the vehicle is fitted with a saddle tank fuel system this feature includes diagnostics for both of the sending units and diagnostics for a siphon tube that has become disconnected or plugged. The power up test looks to see a large enough fuel level voltage change from the last key-off to the following engine run. The engine run test looks to see a fuel level voltage change over an accumulated mileage.

Vehicles fitted with saddle fuel tank configurations have two Fuel Level Sensors. The primary side of the tank has the filler tube inlet near the bottom and contains the Fuel Pump Module. During fuel tank fills, fuel must overflow the primary side to reach the secondary side of the tank. As fuel is consumed, a siphon tube is used to draw fuel from the secondary side to the primary side. Because the siphon tube flow rate exceeds the fuel consumption rate, the secondary side of the tank will be empty before fuel is depleted from the primary side. Fuel Level Sensor 1 is located on the primary side of the tank. Fuel Level Sensor 2 is located on the secondary side of the tank.

- When Monitored:
With engine run time greater than three minutes and Fuel Level Sensor 1 reading high.

- Set Condition:
The Powertrain Control Module (PCM) detects no change in Fuel Level Sensor 2 circuit voltage after a significant amount of fuel should have been consumed based on a calculated value and the vehicle operating conditions.





Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Pre-Diagnostic Troubleshooting Procedure.

1. ACTIVE DTC

NOTE: Diagnose and repair any Can bus, communication or implausible signal DTCs before proceeding with this test.

NOTE: Diagnose P2067 or P2068 first, if set along with P2066.

1. Start the engine.
2. Allow the engine to reach normal operating temperature.
3. With the scan tool, select View DTCs.

NOTE: It may be necessary to drive the vehicle to meet the conditions to set this DTC, try to repeat the conditions in which the fault originally set by reviewing the Freeze Frame data.

Is the DTC Active or Pending at this time?

Yes

- Go To 2

No

- Perform the INTERMITTENT CONDITION diagnostic procedure. Intermittent Condition Test

2. FUEL LEVEL SENSOR CIRCUIT DTCs SET IN THE BCM

Are any Fuel Level Sensor Circuit DTCs set in the BCM?

Yes

- Diagnose the appropriate Fuel Level Sensor Circuit DTC in the BCM. Body Verification Test.

No

- Go To 3

3. VISUALLY INSPECT FUEL TANK
1. Visually inspect the Fuel Tank for damage that may restrict the Fuel Sending Unit float from moving.

Is the Fuel Tank OK?

Yes

- Go To 4

No

- Replace the Fuel Tank as necessary.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

4. (N5) FUEL LEVEL SIGNAL 2 CIRCUIT OPEN/HIGH RESISTANCE




1. Disconnect the Fuel Pump Module harness connector.
2. Disconnect the BCM E harness connector.
3. Measure the resistance of the (N5) Fuel Level Signal 2 circuit from the Fuel Pump Module harness connector to the BCM E harness connector.

Is the resistance above 5.0 Ohms?

Yes

- Repair the open in the (N5) Fuel Level Signal 2 circuit.
- Perform the BODY VERIFICATION TEST. Body Verification Test.

No

- Go To 5

5. (G109) FUEL LEVEL SENSE RETURN CIRCUIT OPEN/HIGH RESISTANCE




1. Measure the resistance of the (G109) Fuel Level Signal Sense Return circuit from the Fuel Pump Module harness connector to the BCM E harness connector.

Is the resistance above 5.0 Ohms?

Yes

- Repair the open in the (G109) Fuel Level Signal Sense Return circuit.
- Perform the BODY VERIFICATION TEST. (Refer to DTC-Based Diagnostics/MODULE, Body Control (BCM) - Standard Procedure).

No

- Go To 6

6. INTERNAL INSPECTION OF THE FUEL TANK

WARNING: The fuel system is under a constant pressure (even with the engine off). Before testing or servicing any fuel system hose, fitting or line, the fuel system pressure must be released. Failure to follow these instructions can result in possible serious or fatal injury.

1. Remove the Fuel Tank. Fuel Tank - Removal.
2. Remove the Fuel Pump Module. Fuel Pump Module - Removal.
3. Visually inspect the inside of the Fuel Tank for any obstructions or deformities.
4. Inspect the Fuel Pump Module Float arm for damage.

Were any problems found?

Yes

- Repair or replace as necessary.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test

No

- Go To 7

7. POWERTRAIN CONTROL MODULE (PCM)
1. Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the Body Control Module (BCM) and the Powertrain Control Module (PCM).
2. Look for any chafed, pierced, pinched or partially broken wires.
3. Look for broken, bent, pushed out or corroded terminals. Verify that there is good pin to terminal contact in the Sensor and Powertrain Control Module connectors.
4. Perform any Technical Service Bulletins that may apply.

Were there any problems found?

Yes

- Repair as necessary.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Replace and program the Powertrain Control Module. Powertrain Control Module - Removal.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.