Start by checking the "Possible Causes" listed above. Visually inspect the related wiring harness and connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector's pins.
The cost to diagnose the B1204 MERCURY code is 1.0 hour of labor. The auto repair's diagnosis time and labor rates vary by location, vehicle's make and model, and even your engine type. Most auto repair shops charge between $75 and $150 per hour.
The fuel pump module is hardwired to the Instrument Cluster (IC). The fuel level sensor (part of the pump module) is a variable resistor actuated by a float with resistance ranging between 180 ohms ± 4 ohms at empty (E) to 10 ohms ± 2 ohms at full (F). The instrument cluster (IC) provides a reference voltage to the fuel pump module on the input circuit. As the fuel level changes, the fuel level sensor float moves up or down according to the fuel level altering the fuel level signal voltage through the resistor. The instrument cluster (IC) interprets this signal and commands the fuel gauge pointer to sweep to the correct level.
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