Circuit Description
The fuel level sender changes resistance based on fuel level. The engine control
module (ECM) 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 ECM
senses a high signal voltage. When the fuel tank is empty, the sender resistance is
low and the ECM senses a low signal voltage. The ECM 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 percent via the class 2 serial data circuit to
the instrument cluster in order to control the fuel gage. The fuel level information
is also used for misfire and EVAP diagnostics.
This diagnostic tests for a stuck primary fuel level sensor signal. The ECM
sets this DTC if the primary 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 P2066 Fuel Level Sensor 2 Performance
Conditions for Running the DTC
| • | No other fuel level sensor signal failure is present. |
Conditions for Setting the DTC
| • | The ECM does not detect a change in fuel level in the primary fuel tank
of at least 1.0L (0.246 gal). |
| • | The difference between fuel consumed by the engine and a change in fuel
level signal exceeds 46%. |
| • | The above condition is present for at least 300 seconds. |
Action Taken When the DTC Sets
| • | The fuel gage defaults to empty. |
| • | The driver information center (DIC) displays the FUEL LEVEL LOW message. |
| • | The ECM records the operating conditions at the time that the diagnostic
test fails. The ECM 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 ECM 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. |
