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For 1990-2009 cars only
Makes 🢒 Oldsmobile 🢒 2000 🢒 Intrigue 🢒 Body and Accessories 🢒 Wiring Systems 🢒 Fuel Level Sensor Diagnosis

Refer to Engine Control Schematics

PCM Fuel Tank Inputs


Object Number: 590098 Size: FS
Engine MaxiFuses, Underhood Fuses and Ignition Main Relay
Ground G302 2 of 2
Ground G113
Ground G113
Handling ESD Sensitive Parts Notice
Engine Controls Component Views
Powertrain Control Module Description
PCM Emission Inputs
Crankshaft and Camshaft Position Sensor
OBD II Symbol Description Notice
 .

Circuit Description

The powertrain control module (PCM) requires an accurate indication of the fuel level for the EVAP system diagnosis. The fuel level in the fuel tank changes the rate of vacuum decay for the EVAP system leak DTCs.

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 of about 5 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 the fuel level.

When the fuel tank is full, the sensor resistance is high, and the signal voltage is only pulled down a small amount through the sensor to ground. Therefore, the PCM will sense a high signal voltage. When the fuel tank is empty, the sensor resistance is low, and the signal voltage is pulled down a larger amount. This causes the PCM to sense a low signal voltage. The fuel level data is also sent to the instrument panel cluster (IPC) via the Serial Data line.

The normal resistance values of the sensor are as follows:

    • 40 ohms plus or minus 2.5 ohms = Full
    • 248.5 ohms plus or minus 3.3 ohms = Empty

This diagnostic table requires the following special tools:

J 33431-C Signal Generator/Instrument Panel Tester

Diagnostic Aids

Important: The fuel level is used to in EVAP system diagnosis. Always diagnose the fuel level sensor before any other EVAP system components or DTCs.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. At 40 ohms the scan tool should display a fuel level close to 0 percent. At 248 ohms the display should be close to 100 percent. As the resistance is increased, there should be a corresponding fuel level increase. If any spikes, dips, or erratic readings occur, or if the low and high resistance values do not correspond closely to 0 percent and 100 percent, the related circuitry should be checked before replacing the sensor.

    2.

  2. Before replacing the sensor, check for the possibility of foreign material in the fuel tank that may inhibit the correct float arm movement, including ice. Check for the float arm contacting other components on the fuel pump and sender assembly.

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

Is DTC P0462, P0463, or any IPC DTC set?

--

Go to the applicable DTC tables

Go to Step 3

3

  1. Turn the key to Off.
  2. Disconnect the fuel level sensor.
  3. Connect the J 33431-C signal generator and instrument panel tester to the fuel level signal and sensor ground circuits in order to perform the Instrument Sender Substitution Test. Refer to the tool instructions for details on this procedure.
  4. Using the instrument panel tester, set the resistance to the first specified value.
  5. Turn the key to On.
  6. Clear any DTCs using the scan tool.
  7. Observe the fuel level with the scan tool.
  8. Slowly dial in additional resistance until the second value is reached.

Does the fuel level increase steadily through the specified range, from 0 percent to 100 percent?

40 ohms

248 ohms

Go to Step 4

Go to Step 5

4
  1. Turn the key to Off.
  2. Using the instrument panel tester, reset the resistance to the first specified value.
  3. Turn the key to On.
  4. Clear any DTCs using the scan tool.
  5. Observe the fuel gauge in the IPC.
  6. Slowly dial in additional resistance until the second value is reached.

Does the fuel gauge increase steadily throughout the specified range, from Empty to Full?

40 ohms

248 ohms

Go to Step 6

Go to Diagnostic System Check - Instrument Cluster in Instrument Panel, Gauges, and Console

5
  1. Turn the key to Off.
  2. Disconnect the PCM.
  3. Check for the following conditions:
    4. • Any poor connections or terminal tension of the fuel level signal and sensor ground circuits at the PCM and at the sensor connector. Refer to Diagnostic System Check - Instrument Cluster in Instrument Panel, Gauges, and Console. .
    • Using a digital multimeter (DMM), check the harness between the PCM and the sensor for a high resistance on both circuits.
    • Using the DMM, measure the resistance between the signal circuit and a known good ground. No continuity should be indicated (OL).
    • Using the DMM, measure the resistance between the signal circuit and all other circuits in the PCM connectors and at the fuel tank connector. No continuity should be indicated (OL).

Was a problem found and corrected?

--

System OK

Go to Step 8

6

Check for poor connections or terminal tension at the fuel level sensor. Refer to Intermittents and Poor Connections Diagnosis in Wiring Systems .

Was a problem found and corrected?

--

System OK

Go to Step 7

7

Replace the fuel level sensor. Refer to Fuel Sender Assembly Replacement .

Is the action complete?

--

System OK

--

8

Important: The replacement PCM must be programmed.

Replace the PCM. Refer to Powertrain Control Module Replacement/Programming .

Is the action complete?

--

System OK

--