Circuit Description
The fuel level sensor changes resistance in response to the fuel level. The powertrain control module (PCM) monitors the signal circuit of the fuel level sensor in order to determine the fuel level. When the fuel tank is full, the sensor resistance is low and the PCM senses a low signal voltage. When the fuel tank is empty, the sensor resistance is high and the PCM senses a high signal voltage. The PCM uses the signal circuit of the fuel level sensor in order to calculate the percentage of remaining fuel in the tank. The PCM sends the fuel level message via the GMLAN serial data circuit to the body control module (BCM). The BCM sends a GMLAN message to the instrument panel cluster (IPC) in order to display the fuel level percent on the fuel gage. The fuel level information is also used for misfire and evaporative emission (EVAP) diagnostics.
This diagnostic tests for a stuck fuel level sensor signal. The PCM sets this DTC if the fuel level sensor signal appears to be stuck based on a lack of signal variation expected during normal operation.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P0461 Fuel Level Sensor Circuit Performance
Conditions for Running the DTC
The engine is running.
Conditions for Setting the DTC
The PCM does not detect a change in fuel level of at least 1.6 percent over a distance of 193 km (120 miles).
Action Taken When the DTC Sets
| • | The fuel gage defaults to empty. |
| • | The low fuel indicator illuminates. |
| • | The PCM records the operating conditions at the time that the diagnostic test fails. The PCM displays the failure information in the Failure Records on the scan tool. |
Conditions for Clearing the DTC
| • | The DTC becomes history when the conditions for setting the DTC are no longer present. |
| • | The history DTC clears after 40 malfunction free warm-up cycles. |
| • | The PCM receives the clear code command from the scan tool. |
Diagnostic Aids
| • | Use the Freeze Frame/Failure Records data in order to locate an intermittent condition. If you cannot duplicate the DTC, the information included in the Freeze Frame/Failure Records data may help in determining the number of miles since the DTC set. The Fail Counter and Pass Counter can also help in determining the number of ignition cycles that the diagnostic test reported a pass and/or fail. Operate the vehicle within the same freeze frame conditions, including those for RPM, for engine load, for vehicle speed, for temperature, and for others. This will isolate at what point the DTC failed. |
| • | Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems. |
Step | Action | Yes | No | ||||
|---|---|---|---|---|---|---|---|
Schematic Reference: Instrument Cluster Schematics | |||||||
1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information | ||||
2 |
Did you find and correct the condition? | Go to Step 4 | Go to Step 3 | ||||
3 | Replace the fuel level sensor. Refer to Fuel Level Sensor Replacement in Engine Controls - 3.5L. Did you complete the replacement? | Go to Step 4 | -- | ||||
4 |
Does the DTC reset? | Go to Step 2 | System OK | ||||
