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For 1990-2009 cars only
Makes 🢒 Pontiac 🢒 1998 🢒 Grand Prix 🢒 Engine 🢒 Engine Controls - 3.8L 🢒 Fuel Level Sensor Diagnosis

Object Number: 240277 Size: SF
Fuel Pump Controls - RPO L36
OBD II Symbol Description Notice
Handling ESD Sensitive Parts Notice
Handling ESD Sensitive Parts Notice
Engine Controls Component Views

Circuit Description

The 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 to calculate the amount of fuel in the tank. The PCM uses the fuel level sensor information to control the fuel gauge via the fuel level output control circuit.

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

Diagnostic Aids

Refer to Instrument Cluster System Check in Instrument Panel Gauges and Console for additional diagnostic information.

Check for the following condition(s):

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

Test Description

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

Was the Powertrain On-Board Diagnosis System Check performed?

--

Go to Step 2

Go to the Powertrain OBD System Check

2

Are there any other DTCs set?

--

Diagnose the other DTCs first.

Go to Step 3

3
  1. Turn the ignition switch OFF.
  2. Remove the fuel sender access panel. Refer to Fuel Level Sensor Replacement .
  3. Disconnect the fuel level sensor connector.
  4. Turn the ignition switch ON.
  5. Observe the fuel gauge for up to 30 seconds.

Does the fuel gauge indicate FULL?

--

Go to Step 4

Go to Step 6

4
  1. Leave the ignition switch turned ON.
  2. Connect J 39200 Digital Multimeter (DMM) between the fuel level sensor feed circuit and ground.

Does the DMM display a voltage greater than the specified value?

5V

Go to Step 5

Go to Step 7

5
  1. Turn the ignition switch OFF.
  2. Disconnect the PCM connector.
  3. Turn the ignition switch ON.
  4. Probe the fuel level feed circuit with J 34142-B test light connected to ground.

Is the test light ON?

--

Go to Step 10

Go to Step 13

6
  1. Turn the ignition switch OFF.
  2. Disconnect the PCM.
  3. Turn the ignition switch ON.
  4. Connect the test light to battery positive.
  5. Probe the fuel level sensor feed circuit.

Is the test light ON?

--

Go to Step 11

Go to Step 13

7
  1. Leave the ignition switch turned ON.
  2. Connect a jumper between the fuel level sensor feed and sensor ground circuits.
  3. Observe the fuel gauge for up to 30 seconds.

Does the fuel gauge indicate EMPTY?

--

Go to Step 8

Go to Step 9

8
  1. Check for poor terminal connections at the fuel level sensor.
  2. If a problem is found, repair as necessary. Refer to Wiring Repairs in Wiring Repairs.

Was a problem found?

--

Go to Step 14

Go to Step 12

9
  1. Check for the following circuit condition(s):
    2. • An open in the fuel level sensor ground.
    • Poor terminal connections at the PCM.
  2. If a problem is found, repair as necessary. Refer to Wiring Repairs in Wiring Systems.

Was a problem found?

--

Go to Step 14

Go to Step 13

10

Locate and repair the short to voltage in the fuel level sensor feed circuit. Refer to Wiring Repairs in Wiring Systems..

Is action complete?

--

Go to Step 14

--

11

Locate and repair the short to chassis or sensor ground. Refer to Wiring Repairs in Wiring Sytems.

Is action complete?

--

Go to Step 14

--

12

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

Is action complete?

--

Go to Step 14

--

13

Replace the PCM

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

Is action complete?

--

Go to Step 14

--

14

Recheck the system for proper operation.

Does the system operate properly?

--

System OK

Go to Step 2