DTC P0462 Fuel Level Sensor Circuit Low Voltage. Buick GL7 (Export) 2000

For 1990-2009 cars

Refer to Engine Controls Schematics

#### Fuel Control

.

### Circuit Description

The Fuel Level Sensor changes resistance based on fuel level. The Fuel Level Sensor has a signal circuit and a ground circuit. The PCM applies a voltage (about 5.0 volts) on the signal circuit to the sensor. The PCM monitors changes in this voltage caused by changes in the resistance of the sensor to determine fuel level.

When the fuel tank is full, the sensor resistance is high, therefore, the PCM will sense a high signal voltage (fuel tank full). When the fuel tank is empty, the sensor resistance is low, and the PCM senses a low signal voltage (fuel tank empty).

The PCM uses inputs from the Fuel Level Sensor to calculate the total fuel remaining in the fuel tank. This information is then sent to the fuel gauge.

This DTC sets when the PCM senses a signal voltage lower than the normal operating range of the sensor.

### Conditions for Running the DTC

• | The ignition is ON.

• | System voltage between 10.0-18.0 volts.

### Conditions for Setting the DTC

The fuel level sensor is less than 3.5 percent for more than 25 seconds.

### Action Taken When the DTC Sets

The PCM stores conditions which were present when the DTC set as Failure Records only. This information will not be stored as Freeze Frame Records.

### Conditions for Clearing the MIL/DTC

• | The DTC becomes history when the conditions for setting the DTC are no longer present.

• | The history DTC clears after 40 malfunction free warm-up cycles.

• | The PCM receives a clear code command from the scan tool.

### Diagnostic Aids

Important: Remove any debris from the connector surfaces before servicing a component. Inspect the connector gaskets when diagnosing or replacing a component. Ensure that the gaskets are installed correctly. The gaskets prevent contaminate intrusion.

• | Poor terminal connection-Inspect the harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and faulty terminal to wire connection. Use a corresponding mating terminal to test for proper tension.

• | Damaged harness--Inspect the wiring harness for damage. If the harness inspection does not reveal a problem, observe the display on the scan tool while moving connectors and wiring harnesses related to the sensor. A change in the scan tool display may indicate the location of the fault.

• | PCM and engine grounds for clean and secure connections

If the DTC is determined to be intermittent, reviewing the Failure Records can be useful in determining when the DTC was last set.

### Test Description

The numbers below refer to the step numbers on the Diagnostic Table:

1. This step determines if the fault is present. A short to ground on the Fuel Level Signal circuit will cause all components that use a 5 volt reference to indicate a low voltage. This condition will set many DTCs, Including DTC P1635.

#### DTC P0462 - Fuel Level Circuit Voltage Low

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

1. Turn ON the ignition, with the engine OFF.
2. With a scan tool, monitor the Fuel Level sensor display on the scan tool.

Does the scan tool indicate the Fuel Level sensor parameter below 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. Operate the vehicle within the conditions required for this diagnostic to run, and as close to the conditions recorded in Freeze Frame and/or Failure Records as possible.
5. With a scan tool, observe the DTC information.

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

--

Go to Step 4

Go to Diagnostic Aids

4

1. Disconnect the fuel tank wiring harness at the body pass through connector located near the fuel tank.
2. With a scan tool, observe the Fuel Level sensor parameter.

Does the scan tool indicate the Fuel Level sensor parameter above the specified value?

98%

Go to Step 6

Go to Step 5

5

1. Turn OFF the ignition.
2. Disconnect the PCM.
3. Test the Fuel Level sensor signal circuit for a short to ground. Refer to Testing for Continuity , Wiring Repairs

Did you find and correct the condition?

--

Go to Step 9

Go to Step 8

6

1. Lower the fuel tank to gain access if necessary. Refer to Fuel Tank Replacement .
2. Inspect the fuel tank wiring harness for the following:

• | Short to ground.

• | Damage to the harness.

• | Broken or rubbed through wires.

3. If you find a condition, repair as necessary. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 9

Go to Step 7

7 | Replace the Fuel Level sensor. Refer to Fuel Level Sensor Replacement . Did you complete the replacement? | -- | Go to Step 9 | --
8 | Important:: The replacement PCM must be programmed. Replace the PCM. Refer to Powertrain Control Module Replacement/Programming . Did you complete the replacement? | -- | Go to Step 9 | --

9

1. With a scan tool, select the Diagnostic Trouble Code (DTC) option and the Clear DTC Information.
2. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text, if applicable.

Does the scan tool indicate that this test ran and passed?

--

System OK

Go to Step 2