GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 1999 🢒 Sonoma Pickup - 2WD 🢒 DTC 🢒 DTC P0462 Fuel Level Sensor Circuit Low Voltage

Object Number: 387285 Size: MF
Engine Controls Components
Cell 20: Fuel Level and Fuel Tank Pressure Sensors
OBD II Symbol Description Notice
Powertrain Control Module Connector End Views
Handling ESD Sensitive Parts Notice
Handling ESD Sensitive Parts Notice

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 is less than 3.5% for 25 seconds or more.

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 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.

    2.

  2. This step simulates a DTC P0463. If the PCM senses the change, then the PCM and the Fuel Level Sensor wiring are OK.

    3.

  3. The replacement PCM must be programmed and the Crankshaft Position System Variation Learn Procedure must be performed. Refer to the latest Techline procedure for PCM programming.

Step

Action

Value(s)

Yes

No

1

Was the Powertrain On-Board Diagnostic (OBD) System Check performed?

--

Go to Step 2

Go to

Powertrain On Board Diagnostic (OBD) System Check

2
  1. Turn ON the ignition leaving the engine OFF.
  2. Install a scan tool.
  3. Observe the fuel level sensor reading on the scan tool.

Is the fuel level sensor value less than the specified value?

3.5%

Go to Step 4

Go to Step 3

3
  1. Turn ON the ignition leaving the engine OFF.
  2. Review the Freeze Frame and/or Failure Records data for this DTC and observe the parameters.
  3. Turn OFF the ignition for 15 seconds.
  4. Start the engine.
  5. Operate the vehicle within the conditions required for this diagnostic to run, and as close to the conditions recorded in the Freeze Frame/Failure Records as possible. Special operating conditions that you need to meet before the PCM will run this diagnostic, where applicable, are listed in Conditions for Running the DTC.
  6. Select the Diagnostic Trouble Code (DTC) option, the Specific DTC option, then enter the DTC number using the scan tool.

Does the scan tool indicate that this diagnostic failed this ignition?

--

Go to Step 4

Go to Diagnostic Aids

4
  1. Turn OFF the ignition.
  2. Disconnect the Fuel level sensor harness connector.
  3. Inspect the connector for corrosion and improper mating.
  4. Repair the connector as necessary. Refer to Connector Repairs in Wiring Systems.

Was a repair necessary?

--

Go to Step 9

Go to Step 5

5

With the Fuel level sensor harness connector disconnected, observe the Fuel Level Sensor reading on the scan tool.

Is the fuel level sensor value more than the specified value?

98%

Go to Step 6

Go to Step 7

6
  1. Check the fuel level sensor signal circuit for a short to ground.
  2. Repair the circuit as necessary. Refer to Wiring Repairs in Wiring Systems.

Was a repair necessary?

--

Go to Step 9

Go to Step 8

7

Replace the fuel level sensor. Refer to Fuel Level Sensor Replacement .

Is the action complete?

--

Go to Step 9

--

8

Inportant:: The replacement PCM must be programmed. Refer to Powertrain Control Module Replacement/Programming .

Replace the PCM.

Is the action complete?

--

Go to Step 9

--

9
  1. Using the scan tool, clear the DTCs.
  2. Start the engine and idle at normal operating temperature.
  3. Operate the vehicle within the conditions for setting this DTC as specified in the supporting text.

Does the scan tool indicate that the diagnostic ran and passed?

--

Go to Step 10

Go to Step 2

10

Check if any additional DTCs are set.

Are any DTCs displayed that have not been diagnosed?

--

Go to the applicable DTC table

System OK