DTC P2066 4.8L, 6.0L, and 8.1L Engines

The primary fuel level sender and the secondary fuel level sender changes resistance based on fuel level. The powertrain control module (PCM) monitors the signal circuits of the primary fuel level sender and the secondary fuel level sender in order to determine the fuel level. When the fuel tank is full, the resistance of both fuel level senders are low and the PCM senses a low signal voltage on both the signal circuits of the primary fuel level sender and the secondary fuel level sender. When the fuel tanks are empty, the resistance of the fuel level senders are high and the PCM senses a high signal voltage. The PCM uses the signal circuits of the primary fuel level sender and the secondary fuel level sender in order to calculate the percentage of remaining fuel in the tank. The PCM sends the fuel level percentage 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 evaporative emission (EVAP) diagnostics.

This diagnostic tests for a stuck secondary fuel level sender signal. The PCM sets this DTC if the secondary fuel level sender signal appears to be stuck based on a lack of signal variation expected during normal operation.

The engine is running.

The PCM does not detect a change in the secondary fuel level of at least 3.0 L (0.79 gal) over a distance of 320 km (200 mi).

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 (RPM, engine load, vehicle speed, temperature, etc.). This will isolate when the DTC failed.

Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

DTC P2066 5.3L Engine

The primary fuel level sender and the secondary fuel level sender changes resistance based on fuel level. The PCM monitors the signal circuits of the primary fuel level sender and the secondary fuel level sender in order to determine the fuel level. When the fuel tank is full, the resistance of both fuel level senders are high and the PCM senses a high signal voltage on both the signal circuits of the primary fuel level sender and the secondary fuel level sender. When the fuel tanks are empty, the resistance of the fuel level senders are low and the PCM senses a low signal voltage. The PCM uses the signal circuits of the primary fuel level sender and the secondary fuel level sender in order to calculate the percentage of remaining fuel in the tank. The PCM sends the fuel level percentage 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 secondary fuel level sender signal. The PCM sets this DTC if the secondary fuel level sender signal appears to be stuck based on a lack of signal variation expected during normal operation.

The engine is running.

The PCM does not detect a change in the secondary fuel level of at least 3.0 L (0.79 gal) over a distance of 320 km (200 mi).

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 (RPM, engine load, vehicle speed, temperature, etc.). This will isolate when the DTC failed.

Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.