Circuit Description
The fuel level sender changes resistance based on the fuel level. The powertrain control module (PCM) monitors the signal circuit of the fuel level sender in order to determine fuel level. When the fuel tank is full, the sender resistance is high and the
PCM senses a high signal voltage. When the fuel tank is empty, the sender resistance is low and the PCM senses a low signal voltage. The PCM uses the signal circuit of the fuel level sender in order to calculate the total remaining fuel percent in the tank.
The ECM sends the fuel level message via the GMLAN serial data circuit to the body control module (BCM). The BCM sends 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 an intermittent fuel level sensor signal. If a change in fuel level is detected, the engine-off natural vacuum small leak test DTC P0442 is aborted due to a refueling event. Before aborting DTC P0442 a refueling
event test is executed to confirm that a refueling event has occurred. If refueling is confirmed, the test is considered a pass. Otherwise, the DTC P0464 sets indicating an intermittent signal problem.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P0464 Fuel Level Sensor Circuit Intermittent
Conditions for Running the DTC
Conditions for Setting the DTC
| • | The fuel level change is greater than 10 percent during engine off test. |
| • | The above condition is present for greater than 30 seconds. |
Action Taken When the DTC Sets
| • | The PCM records the operating conditions at the time the diagnostic 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 and/or Failure Records data in order to locate an intermittent condition. If you cannot duplicate the DTC, the information included in the Freeze Frame and/or Failure Records data may aid in determining the number of miles since
the DTC set. The Fail Counter and Pass Counter can also aid in determining the number of ignition cycles that the diagnostic reported a pass and/or fail. Operate the vehicle within the same freeze frame conditions, i.e. RPM, engine load, vehicle speed, temperature,
etc. This will isolate when the DTC failed. |
