The speedometer and the odometer operate in the following manner:
The fuel level sender provides a signal to the instrument cluster. The signal is proportional to the fuel level. When the fuel tank is full, the fuel level sender resistance is 248 ohms. When the fuel tank is empty, the resistance is near 40 ohms. This instrument cluster converts the analog signal from the fuel level sender to a digital signal. The instrument cluster displays the fuel tank level.
The instrument cluster receives the engine coolant temperature data from the powertrain control module (PCM). The signal travels over the universal asynchronous receiving/transmitting (UART) serial data line. The instrument cluster converts the serial data. The instrument cluster displays the engine coolant temperature.