| Table 1: | Fuel Level Sensor Inspection |
Circuit Description
The DTC P0463 Fuel Level Sensor Circuit High Voltage diagnostic monitors the fuel level sensor signal for a high voltage. The powertrain control module (PCM) uses the fuel level input from the fuel level sensor in order to calculate the expected vapor pressures within the fuel system. The vapor pressures vary as the fuel level changes. The vapor pressure is critical to determining if the evaporative emission (EVAP) control system is operating properly. The fuel level information is used in determining whether to run an EVAP control system diagnostic. A fuel level that is too high or too low may prevent the EVAP control system diagnostics from accurately detecting a fault.
Condition for Running the DTC
The ignition is On or the engine is running.
Conditions for Setting the DTC
| • | The fuel level sensor input circuit voltage is more than a specified value. |
| • | The condition is present continuously for at least 5 seconds. |
Action Taken When the DTC Sets
| • | The PCM illuminates the malfunction indicator lamp (MIL) after 2 consecutive ignition cycles in which the diagnostic runs with the fault active. |
| • | The PCM records the operating conditions at the time the diagnostic fails. This information is stored in the Freeze Frame buffer. |
| • | The PCM enters the Failsafe mode and operates as if the fuel level is 100 percent. |
Conditions for Clearing the MIL/DTC
| • | The MIL turns off after 3 consecutively passing trips without a fault present. |
| • | A history DTC clears after 40 consecutive warm-up cycles without a fault. |
| • | Perform the scan tool Clear DTC Information function. |
Diagnostic Aids
The scan tool will display a default value of 100 percent all the time when a Current fuel level sensor circuit DTC is present. Clear any current or stored fuel level sensor circuit DTCs before diagnosing the fuel level sensor circuit with a scan tool.
An open or a short to ignition voltage in the fuel level sensor circuit will indicate a 0 percent fuel level on the scan tool.
A short to ground in the fuel level sensor circuit will indicate a 100 percent fuel level on the scan tool.
Check the resistance of the fuel level sensor at the following positions:
Fuel Level Position | Resistance Measurement |
|---|---|
Full Tank | 10 ohms or less |
Half Tank | 30 to 35 ohms |
Empty Tank | 100 ohms or more |
Check for a faulty electrical connection at the PCM.
If DTC P0463 is intermittent, driving the vehicle under the following conditions can verify whether the fault is present. Perform the scan tool Clear DTC Information function. Road test the vehicle while monitoring the DTC P0463 diagnostic on the scan tool under the Not Ran Since Code Cleared selection in the DTC Information menu. If a DTC P0463 appears in the Not Ran Since Code Cleared list, the P0463 diagnostic has not yet run. When the DTC P0463 does not appear in the Not Ran Since Code Cleared list, the P0463 diagnostic has run. If the MIL is NOT illuminated, and there is no Pending DTC Status in DTC Information, the P0463 diagnostic has passed. The DTCs MUST be cleared in order to view the Current Status of the Not Ran Since Code Cleared list. DO NOT forget that the Not Ran Since Code Cleared list only indicates that the test has run, not whether the test passed or failed. The DTC Information screen must be checked for Current or Pending status in order to determine the outcome of the diagnostic test involved.
An intermittent malfunction may be caused by a problem in the fuel level sensor electrical circuit. Inspect the wiring harness and components for any of the following conditions:
| • | Any backed-out terminals |
| • | Any improper mating of terminals |
| • | Any broken electrical connector locks |
| • | Any improperly formed or damaged terminals |
| • | Any faulty terminal-to-wire connections |
| • | Any physical damage to the wiring harness |
| • | A broken wire inside the insulation |
| • | Any corrosion of the electrical connections, the splices, or the terminals |
If the DTC P0463 cannot be duplicated, the information included in the Freeze Frame data can be useful in determining the vehicle operating conditions when the DTC was first set.
Test Description
The numbers below refer to the step numbers in the diagnostic table.
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The Powertrain OBD System Check prompts the technician to complete some basic checks and store the Freeze Frame data on the scan tool if applicable. This creates an electronic copy of the data taken when the fault occurred. The information is then stored in the scan tool for later reference.
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This step determines if the fault that set the DTC is still present.
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This step checks for a faulty PCM. If the fuel gage indicates the correct amount of fuel, there is a voltage fault within the PCM.
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In order to locate the C401 connector, follow the fuel tank wire harness to the square pass-through grommet. The grommet is located in the frame rail below the left taillight assembly. Gently pull the grommet and harness out of the frame rail. The C401 connector is located a couple of inches from the pass-through grommet.
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Clearing the DTCs by removing the DOME fuse also clears the PCM long term memory. Using the scan tool to clear DTCs leaves the long term memory active. DTC emitting diagnostics may not run to completion as expected unless the long term memory is cleared. Removal of the DOME fuse also clears the time display of the radio. The DTC P0463 diagnostic can be monitored on the scan tool under the Not Ran Since Code Cleared selection in the DTC Information menu. If a DTC P0463 appears in the Not Ran Since Code Cleared list, the DTC P0463 diagnostic has not yet run. When the DTC P0463 does not appear in the Not Ran Since Code Cleared list, the DTC P0463 diagnostic has run. If the MIL is NOT illuminated, and there is no Pending DTC Status in DTC Information, the DTC P0463 diagnostic has passed. The DTCs MUST be cleared in order to view the Current Status of the Not Ran Since Code Cleared list. DO NOT forget that the Not Ran Since Code Cleared list only indicates that the test has run, not whether the test passed or failed. The DTC Information screen must be checked for Current or Pending status, in order to determine the outcome of the diagnostic test involved.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
Schematic Reference: Instrument Cluster Schematics | ||||
Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | Go to Step 2 | Go to Diagnostic System Check - Engine Controls in Engine Controls | |
Is there a Pending or Current DTC P0463 set? | -- | Go to Step 3 | Go to Diagnostic Aids | |
Does the fuel gage indicate EMPTY? | -- | Go to Step 4 | Go to Step 11 | |
Is the voltage within the specified range? | 7-8 V | Go to Step 5 | Go to Step 7 | |
5 |
Is the voltage within the specified range? | 7-8 V | Go to Step 6 | Go to Step 8 |
6 |
Was a repair necessary? | -- | Go to Step 12 | Go to Step 9 |
7 |
Was a repair necessary? | -- | Go to Step 12 | Go to Step 10 |
8 | Repair the open in the signal wire of the fuel level sensor between the sensor harness connector C401 and the fuel level sensor. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | Go to Step 12 | -- |
9 | Replace the fuel level sensor. Refer to Fuel Sender Assembly Replacement in Engine Controls. Is the action complete? | -- | Go to Step 12 | -- |
10 | Repair the open in the fuel level sensor signal wire between the harness connector C401 and the S258. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | Go to Step 12 | -- |
Does the DTC run and pass? | -- | Go to Step 12 | -- | |
12 |
Are any DTCs displayed on the scan tool? | -- | Go to Diagnostic Trouble Code (DTC) List in Engine Controls | System OK |
