P0462

Diagnostic Chart:

Schematic:

Fuel level information is accomplished by using two variable resistance fuel level sensors in series, which vary resistance according to changes in the level of fuel in the fuel tank. The ECM supplies a 5 volt reference through a pull-up resistor to the primary fuel level sensor, which is part of an assembly to the primary fuel pump module (right side of fuel tank). The primary fuel level sensor is electrically connected to the secondary fuel level sensor, which is part of an assembly to the secondary fuel pump module (left side of fuel tank). The secondary fuel level sensor is connected to ground. When the level of fuel in the fuel tank is high, each sensor resistance is low (low voltage on signal line). As the fuel level decreases, the sensor resistances increase (higher voltage on signal line). The ECM monitors the fuel level sensor signal voltage to determine fuel tank level. The fuel level sensor signal voltage ranges between 400 mV to 2.5 volts with each sender arm at the highest and lowest positions. The ECM will send this fuel level information over the CAN link to the BCM. The BCM in turn will average this information with respect to vehicle speed, then send it over the Class II link to the I/P cluster who will position the fuel gauge. DTC P0462 will set if the fuel level sensor signal voltage at the ECM is below the calibrated voltage value.

DTC PARAMETERS
DTC P0462 will set if fuel level sensor signal voltage is less than 0.21 volts when:
^ Condition exists for longer than 5 seconds
^ Main relay voltage is between 9.0 and 18.0 volts

DTC P0462 diagnostic runs continuously with ignition On.

P0462 is a type D DTC

DIAGNOSTIC AIDS

NOTE: FUEL LEVEL SENSOR voltage on Scan tool is instantaneous, NOT averaged.

To locate an intermittent problem, use Scan tool to monitor FUEL LEVEL SENSOR with ignition On, engine Off. Wiggling wires while watching for a change in FUEL LEVEL SENSOR voltage may locate the area where a short to ground in the wiring may exist.

If DTC P0462 is active, the Fuel gauge will take around 15 seconds to go to empty as long as no vehicle speed is present with the transmission in Park. If these conditions are not met, the fuel gauge may take a long time to reach empty.

The Low Fuel telltale will NOT be commanded On if DTC P0462 is active.

Each fuel level sensor resistance: 19 ohms with float at top position (full fuel tank); though 125 ohms with float at bottom position (empty fuel tank).

The fuel tank inline harness connector contains a voltage tap wire that is connected between the primary and secondary fuel level sensor. As a result, this wire in conjunction with the 5 volt supply and reference return wire to the sensors may be used to take a resistance measurement of each sensor.