GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Oldsmobile 🢒 1999 🢒 Intrigue 🢒 Engine 🢒 Engine Controls - 3.8L 🢒 Fuel Level Sensor Diagnosis

Object Number: 154433 Size: LF
Engine Controls Components
Fuel Control
OBD II Symbol Description Notice

Circuit Description

The powertrain control module (PCM) supplies 5 volts to the fuel level sensor circuit. The fuel level sensor varies the voltage relative to the amount of fuel in the tank. The PCM monitors the voltage on the fuel level circuit in order to calculate the amount of fuel in the tank. The PCM sends fuel level information via the Class 2 serial data to the instrument panel fuel gauge.

The PCM uses fuel level information in order to enable the enhanced evaporative emission diagnostic.

Diagnostic Aids

Inspect for the following condition:

Inspect the harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, faulty terminal to wire connections and damaged harness.

Test Description

The number(s) below refer to the step number(s) on the Diagnostic Table.

  1. This checks for proper PCM voltage, ground and circuit wiring. The PCM supplies 5V to the fuel level sensor.

    2.

  2. This checks for a fuel level sensor circuit shorted to battery positive.

    3.

  3. This checks for a faulty fuel level sensor ground or splice connection.

Fuel Level Sensor Diagnosis

Step

Action

Value(s)

Yes

No

1

Did you perform the Powertrain On-Board Diagnosis System Check?

--

Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check

2

Perform the Instrument Panel Cluster Diagnostic System Check. Refer to Diagnostic System Check - Instrument Cluster in Instrument Panel, Gauges, and Console.

Are there any instrument panel cluster (IPC) DTCs set?

--

Diagnose the IPC DTCs first

Go to Step 3

3

Connect a scan tool.

Turn the ignition switch to the ON position.

Use the scan tool output control function in order to perform the Fuel Gauge Sweep Test.

Does the Fuel Gauge sweep through its full range?

--

Go to Step 4

Go to Fuel Gage Inaccurate or Inoperative in Instrument Panel, Gauges, and Console

4
  1. Turn the ignition switch to the OFF position
  2. Raise the vehicle.
  3. Disconnect the fuel tank pigtail harness from the body connector.
  4. Connect digital multimeter (DMM) between the body connector pins 3B and 3D.
  5. Lower the vehicle
  6. Turn the ignition switch to the ON position.

Is the voltage near the specified value?

5 V

Go to Step 5

Go to Step  6

5
  1. Test for the following circuit conditions:
    2. • An open in the fuel tank pigtail feed or ground circuit(s)
    • Any faulty terminal connections between the fuel tank pigtail and the body connector.
    • Any faulty terminal connections between the fuel tank pigtail and the fuel sender assembly.
  2. If a problem is found, repair as necessary. Refer to Connector Repairs or to Wiring Repairs in Wiring Systems.

Was a problem found?

--

Go to Step  13

Go to Step 10

6

Is the voltage more than the specified value?

5 V

Go to Step 11

Go to Step 7

7

Connect the DMM between the body connector pin 3D and chassis ground.

Does the DMM indicate a voltage near the specified value?

5 V

Go to Step 8

Go to Step  9

8

Locate and repair the following circuit condition(s):

    • An open in the fuel tank pigtail ground circuit.
    • An open or faulty splice in the fuel level sensor ground circuit.
    • A faulty terminal connection between the fuel tank pigtail and the body connector.

Did you complete the repair?

--

Go to Step  13

--

9
  1. Test for the following circuit conditions:
    2. • Any open/faulty terminal connections in the PCM feed circuit to the fuel level sensor.
    • The PCM feed circuit shorted to chassis or sensor ground.
  2. If a problem is found, repair as necessary. Refer to Connector Repairs or to Wiring Repairs in Wiring Systems.

Was a problem found?

--

Go to Step  13

Go to Step 11

10

Replace the fuel level sensor.

Did you complete the repair?

--

Go to Step  13

--

11

Locate and repair short to voltage in the PCM feed to the fuel level sensor.

Is action complete?

--

Go to Step  13

--

12

Important: Replacement PCM must be programmed. Refer to Powertrain Control Module Replacement/Programming .

Replace the PCM

Did you complete the repair?

--

Go to Step  13

--

13

Retest the system for proper operation.

Does the system operate properly?

--

System OK

Go to Step  2