Chrysler Town & Country 2008-2009
Dodge Grand Caravan 2008-2009
The fuel level sending unit is attached to the side of the fuel pump module located in the fuel tank. The sending unit consists of a float, an arm, and a variable resistor track (card). The resistor track is used to send electrical signals to the PCM for fuel gauge and for OBD II emission requirements.
As the fuel level increases, the float and arm move upwards. This action decreases the sending unit resistance, causing the fuel gauge to move toward the F indication. As the fuel level decreases, the float and arm move downwards and the gauge moves to the E indication.
When the electrical signal is sent to the PCM, the PCM transmits the data across the CCD bus circuits to the instrument panel. At this point, it is translated to an appropriate fuel gauge level reading.
For OBD II emission monitor requirements, a voltage signal is sent from the resistor track on the sending unit to the PCM to indicate fuel level. The purpose of this feature is to prevent the OBD II from recording/setting false misfire and fuel system monitor trouble codes. The feature is activated if the level in the tank is less than approximately 15 percent of its rated capacity. If equipped with a leak detection pump, this feature will also be activated if the fuel level in the tank is more than about 85 percent of its rated capacity.