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 low
and the PCM senses a low signal voltage. When the fuel tank is empty, the sender resistance
is high and the PCM senses a high 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 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 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. |
