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SMU - Revised DTC P0461 Fuel Level Sensor Performance Diagnostic Procedure

Subject:Revised DTC P0461 Fuel Level Sensor Performance Diagnostic Procedure

Models:2000 Oldsmobile Alero
2000 Pontiac Grand Am
With 2.4L Engine


This bulletin is being issued to revise the DTC P0461 Fuel Level Sensor Performance diagnostic procedure in the Engine Controls - 2.4L sub-section of the Service Manual. Please replace the current information in the Service Manual with the following information.

The following information has been updated within SI2000. If you are using a paper version of this Service Manual, please make a reference to this bulletin on the affected page.


Object Number: 621238 Size: SF

Conditions for Running the DTC
    • The ignition is ON.
    • The system voltage is between 11 and 16 volts.

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 (VAP) 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

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 which the diagnostic fails. This information will store in the Failure Records buffer.
    • A history DTC stores.
    • The fuel level will default 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
    • Inspect for the following conditions that may cause intermittents:
       - Poor electrical connections
       - Rubbed through wire insulation
       - A wire that is broken inside the wire insulation
    • Thoroughly inspect any circuitry that is suspected as causing the intermittent complaint. Inspect for the following conditions:
       - Backed out terminals
       - Improper mating
       - Broken locks
       - Improperly formed or damaged terminals
       - Poor 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 number below refers to the step number on the diagnostic table.

  1. The replacement PCM must be programmed and the Crankshaft Position System Variation Learn procedure must be performed.

DTC P0461 - Fuel Level Sensor Circuit

Step

Action

Value(s)

Yes

No

1

Did you perform the Powertrain On-Board Diagnostic (OBD) System Check?

--

Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check

2

Are DTC P0462 or P0463 set?

--

Go to

DTC P0462 Fuel Level Sensor Circuit Low Voltage or to DTC P0463 Fuel Level Sensor Circuit High Voltage

Go to Step 3

3
  1. Turn off the ignition.
  2. Disconnect the fuel level sensor connector.
  3. Turn on the ignition, leaving the engine off.
  4. Observe the Fuel Level on the scan tool.

Is the fuel level equal to the specified level?

100%

Go to Step 4

Go to Step 5

4

Connect a jumper wire between the following circuits:

    • The fuel level sensor ground
    • The fuel level sensor signal
    • Observe the Fuel Level on the scan tool.

Does the Fuel Level equal the specified value?

0%

Go to Step 10

Go to Step 6

5
  1. Test the sensor signal circuit for a short to ground.
  2. If a problem is found, repair as necessary. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 12

Go to Step 9

6
  1. Connect a test lamp to B+.
  2. Probe the sensor ground circuit.

Does the test lamp illuminate?

--

Go to Step 7

Go to Step 8

7
  1. Test the sensor signal circuit for the following conditions:
    2. • An open
    • A poor connection
  2. If a problem is found, repair as necessary. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 12

Go to Step 9

8
  1. Test the sensor ground circuit at the PCM for the following conditions:
    2. • An open
    • A poor connection
  2. If a problem is found, repair as necessary. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 12

Go to Step 9

9

Important:: The replacement PCM must be programmed. Refer to PCM Replacement/Programming.

Replace the PCM. Refer to Powertrain Control Module (PCM) Replacement.

Did you complete the repair?

--

Go to Step 12

--

10
  1. Test the sensor connector for the following conditions:
    2. • An open
    • A poor connection
  2. If a problem is found, repair as necessary. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 12

Go to Step 11

11
  1. Turn off the ignition.
  2. Replace the fuel level sensor. Refer to Fuel Level Sensor Replacement.

Did you complete the repair?

--

Go to Step 12

--

12
  1. Use a scan tool to clear the DTCs.
  2. Operate the vehicle within the Conditions for Setting the DTC as specified in the supporting text.

Does the DTC reset?

--

Go to Step 2

System OK