P0461
P0461-FUEL LEVEL SENSOR 1 PERFORMANCEP0461-Fuel Level Sensor 1 Performance:
Theory of Operation
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.
WHEN MONITORED
TEST No.1: With the ignition on, the fuel level is compared to the previous key down after a 20 second delay.
TEST No.2: The PCM monitors the fuel level at ignition on.
SET CONDITION
TEST No.1: If the PCM does not see a difference in fuel level of greater than 0.1 volt the test will fail.
TEST No.2: If the PCM does not see a change in the fuel level of 0.1765 over a set amount of miles the test will fail. Two trip fault. Three good trips to turn off the MIL.
POSSIBLE CAUSES
- (N4) Fuel level signal circuit open
- (N4) Fuel level signal circuit shorted to ground
- Ground circuit open
- (A109) Fused B+ circuit
- Fuel tank
- Fuel level sensor
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding.
Diagnostic Test
1. ACTIVE DTC
NOTE:
- Diagnose any CAN - C or CAN - B Communication DTCs before continuing.
- Diagnose P0462 or P0463 first, if set along with P0461.
Ignition on, engine not running.
With a scan tool, read DTCs.
Q: Is the DTC active at this time?
YES: Go To 2
NO: Refer to the INTERMITTENT CONDITION Diagnostic Procedure. Component Tests and General Diagnostics
Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
2. VISUALLY INSPECT FUEL TANK
Visually inspect the Fuel Tank for damage that may restrict the Fuel Sending Unit float from moving.
Q: Is the Fuel Tank OK?
YES: Go To 3
NO: Replace the Fuel Tank as necessary. Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
3. (A109) FUSED B+ CIRCUIT
Using a 12-volt test light connected to ground, probe the (A109) Fused B+ circuit.
Q: Does the test light illuminate brightly?
YES: Go To 4
NO: Repair the open or short to ground in the (A109) Fused B+ circuit. Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
4. (Z912), (Z210) GROUND CIRCUITS
Using a 12-volt test light connected to B+, probe the (Z912) and (Z210) Ground circuits.
Q: Does the test light illuminate brightly?
YES: Go To 5
NO: Repair the open in the (Z912) and (Z210) Ground circuits. Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
5. (N4) FUEL LEVEL SIGNAL CIRCUIT OPEN
Turn the ignition off.
Disconnect the Fuel Pump Module harness connector.
Disconnect the C1 Cluster harness connector.
Measure the resistance of the (N4) Fuel Level Signal circuit from the Fuel Pump Module harness connector to the C1 Cluster harness connector.
Q: Is the resistance below 5.0 ohms?
YES: Go To 6
NO: Repair the open in the (N4) Fuel Level Signal circuit. Perform BODY VERIFICATION TEST VER - 1. Body Verification Test
6. (N4) FUEL LEVEL SIGNAL CIRCUIT SHORTED TO GROUND
Measure the resistance between ground and the (N4) Fuel Level Signal circuit in the Fuel Pump Module harness connector.
Q: Is the resistance below 100 ohms?
YES: Repair the short to ground in the (N4) Fuel Level Signal circuit. Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
NO: Go To 7
7. 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 PERSONAL INJURY OR DEATH.
Remove the Fuel Tank.
Remove the Fuel Pump Module.
Visually inspect the inside of the Fuel Tank for any obstructions or deformities.
Inspect the Fuel Pump Module Float arm for damage.
Q: Were any problems found?
YES: Repair or replace as necessary. Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
NO: Go To 8
8. FUEL LEVEL SENSOR
If there are no possible causes remaining, view repair.
Repair
Replace the Fuel Level Sensor. Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test