P0462

Diagnostic Chart:

Refer to Engine Controls Schematics L36 Fuel Tank inputs/Outputs and L67 Fuel Tank Inputs/Outputs.

CIRCUIT DESCRIPTION
The Powertrain Control Module (PCM) uses the 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 Emissions 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 EVAP system malfunction.

CONDITIONS FOR SETTING THE DTC
The fuel level sensor should be less than 3.5 percent for more than 25 seconds.

Action Taken When the DTC Sets
^ The PCM records the operating conditions at the time the diagnostic fails. The Failure Records buffers will store this information.
^ A History DTC is stored.
^ The fuel tank level defaults to 40 percent.

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

DIAGNOSTIC AIDS
^ An intermittent problem may be caused by the following conditions:
- Poor electrical connection
- Rubbed through wire insulation
- A wire that is broken inside the wire insulation
^ Any circuitry, that is suspected as causing the intermittent complaint, should be thoroughly checked for the following conditions:
- Backed out terminals
- Improper mating
- Broken locks
- Improperly formed or damaged terminals
- Poor terminal to wire connection

TEST DESCRIPTION
The numbers below refer to the step numbers on the diagnostic table.
1. The powertrain On Board Diagnostic (OBD) System Check prompts the technician to complete some basic checks and store the Freeze Frame and Failure Records data on the scan tool if applicable. This creates an electronic copy of the data taken when the malfunction occurred. The information is then stored in the scan tool for later reference.
3. This step simulates a DTC P0463. If the PCM senses the change, then the PCM and the fuel level sensor wiring are OK.
6. The replacement PCM must be programmed and the crankshaft position variation procedure must be performed. Refer to the latest Techline procedure for PCM reprogramming.