P0461

Diagnostic Chart:

Schematic:

CIRCUIT DESCRIPTION
The Powertrain Control Module (PCM) uses a fuel level input in order to calculate the expected vapor pressures within the fuel system. These vapor pressures vary as the fuel level changes. The vapor pressure is critical in determining if the Evaporative Emission (EVAP) system is operating properly. The PCM also uses the fuel level in order to determine if the fuel level is too high or too low to be able to accurately detect an EVAP system malfunction.

CONDITIONS FOR SETTING THE DTC
The fuel level has not changed more than 1.6 percent in 193 km (120 miles).

ACTION TAKEN WHEN THE DTC SETS
^ The PCM will record the operating conditions during the time in which the diagnostic fails This information will store in the Failure Records buffer.
^ A history DTC is stored.

CONDITIONS FOR CLEARING THE DTC
^ A history DTC clears after 40 consecutive warm up cycles without a fault.
^ Use a scan tool to cleat the DTCs.

DIAGNOSTIC AIDS
^ Inspect for the following conditions that may cause intermittents:
- Faulty electrical connections
- Rubbed-through wire insulation
- A wire that is broken inside the wire insulation
^ Thoroughly inspect any circuitry that is suspected of causing the intermittent complaint. Inspect for the following conditions:
- Backed-out terminals
- Improper mating
- Broken locks
- Improperly formed or damaged terminals
- Faulty terminal-to-wire connections
^ Before replacing the PCM, inspect the PCM electrical connector terminals for the following conditions:
- Improper mating
- Broken locks
- Physical damage to the wiring harness

TEST DESCRIPTION
The numbers below refer to the step numbers on the diagnostic table:
2. The fuel level display on the scan tool is displayed as a percentage of fuel in the fuel tank. It is also important to know approximately how much fuel is in the tank prior to performing this step.
9. The replacement PCM must be programmed and the Crankshaft Position System Variation Learn Procedure must be performed.