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For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2006 🢒 Savana - AWD 🢒 Body 🢒 Wiring Systems 🢒 Fuel Gage Inaccurate or Inoperative

Fuel Gage Inaccurate or Inoperative Single Tank

Diagnostic Aids
    • Verify that the fuel level is in the same range as the customer concern.
    • For intermittent diagnosis, refer to Testing for Intermittent Conditions and Poor Connections.
    • Refer to Fuel Level Specifications in order to verify the correct readings for the fuel level sensor. The Fuel Tank Level Remaining % parameter is available on the scan tool in the powertrain control module (PCM) Enhanced EVAP data list or the Fuel Level Sensor % parameter is available on the scan tool in the PCM Fuel data list - 6.6L diesel only.

Test Description

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

  1. This step tests for a high resistance in the signal circuit and the low reference circuit of the fuel level sensor.

    2.

  2. DTCs will set in the PCM when you perform this diagnostic table.

Step

Action

Values

Yes

No

Schematic Reference: Instrument Cluster Schematics

Connector End View References: Instrument Panel, Gages, and Console Connector End Views, Powertrain Control Module Connector End Views for the 4.3L engine, Powertrain Control Module Connector End Views for the 4.8L, 5.3L, and 6.0L engine or Engine Control Module Connector End Views for the 6.6L (LLY) engine

1

Did you perform the Diagnostic System Check - Vehicle?

--

Go to Step 2

Go to Diagnostic System Check - Vehicle

2
  1. Disconnect C101.
  2. Connect the J 33431-C Signal Generator and Instrument Panel Tester between the signal circuit of the fuel level sensor and the low reference circuit of the fuel level sensor on the female terminal side of the connector.
  3. Turn ON the ignition, with the engine OFF.

    4. Important: Verify the J 33431-C resistance settings with a DMM.

  4. Vary the resistance on the J 33431-C from 40-250 ohms.
  5. Refer to Fuel Level Specifications in order to convert from resistance to fuel gage display.

Does the fuel gage display the correct fuel level?

--

Go to Step 4

Go to Step 3

3

  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.

    3. Important: Verify the J 33431-C resistance settings with a DMM.

  3. Vary the resistance on the J 33431-C from 40-250 ohms.
  4. Refer to Fuel Level Specifications in order to convert from resistance to fuel level percentage.

    5. Important: Turn the ignition OFF momentarily between the resistance settings in order to quickly update the scan tool display.

  5. With the scan tool, observe one of the following fuel level parameters:
    6. • Fuel Tank Level Remaining % parameter in the powertrain control module (PCM) Enhanced EVAP data list - gas only.
    • Fuel Level Sensor % parameter in the Fuel data list - 6.6L diesel only.

Do the Fuel Level % parameters display the correct fuel level percentage?

--

Go to Step 11

Go to Step 5

4

Inspect for the following items:

    • A poor connection at the harness connector of the fuel level sensor--Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs.
    • A high resistance in the signal circuit or the low reference circuit between the fuel level sender and C101
    • A misaligned fuel level sender
    • A deformed fuel tank

Did you find and correct the condition?

--

Go to Step 13

Go to Step 7

5

Test the signal circuit of the fuel level sender for a high resistance between C101 and the PCM. Refer to Circuit Testing and Wiring Repairs.

Did you find and correct the condition?

--

Go to Step 13

Go to Step 6

6

Test the low reference circuit of the fuel level sender for a high resistance between C101 and the PCM. Refer to Circuit Testing and Wiring Repairs.

Did you find and correct the condition?

--

Go to Step 13

Go to Step 9

7
  1. Remove the fuel level sender.
  2. Inspect for the following items:
    3. • The fuel level sensor is stuck, perhaps due to an interference with the fuel strainer.
    • The fuel tank contains foreign material, for instance, ice.

Did you find and correct the condition?

--

Go to Step 13

Go to Step 8

8
  1. With the DMM, measure the resistance of the fuel level sender while moving the float arm.
  2. Observe both the analog and digital displays on the DMM.

Does the resistance change smoothly across the specified range?

40-250 ohms

Go to Diagnostic Aids

Go to Step 10

9

Inspect for poor connections at the harness connector of the PCM. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs.

Did you find and correct the condition?

--

Go to Step 13

Go to Step 12

10

Replace the fuel level sender. Refer to appropriate procedure:

    •  Fuel Level Sensor Replacement for the 4.3L engine
    •  Fuel Level Sensor Replacement for the 4.8L, 5.3L, and 6.0L engine
    •  Fuel Level Sensor Replacement for the 6.6L (LLY) engine

Did you complete the replacement?

--

Go to Step 13

--

11

Replace the instrument panel cluster (IPC). Refer to Control Module References for replacement, setup, and programming.

Did you complete the replacement?

--

Go to Step 13

--

12

Replace the PCM. Refer to Control Module References for replacement, setup, and programming.

Did you complete the replacement?

--

Go to Step 13

--

13

  1. Use the scan tool in order to clear the PCM DTCs.
  2. Operate the system in order to verify the repair.

Did you correct the condition?

--

System OK

Go to Step 2

Fuel Gage Inaccurate or Inoperative Dual Tank

Diagnostic Aids
    • Verify that the fuel level is in the same range as the customer concern.
    • For intermittent diagnosis, refer to Testing for Intermittent Conditions and Poor Connections.
    • Refer to Fuel Level Specifications in order to verify the correct readings for the fuel level sensor. The Fuel Tank Level Remaining % parameter is available on the scan tool in the powertrain control module (PCM) Enhanced EVAP data list or the Fuel Level Sensor % parameter is available on the scan tool in the PCM Fuel data list - 6.6L diesel only.

Test Description

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

  1. This step tests for a high resistance in the signal circuit and the low reference circuit of the fuel level sensor.

    2.

  2. DTCs will set in the PCM when you perform this diagnostic table.

Step

Action

Values

Yes

No

Schematic Reference: Instrument Cluster Schematics

Connector End View References: Instrument Panel, Gages, and Console Connector End Views, Powertrain Control Module Connector End Views for the 4.3L engine, Powertrain Control Module Connector End Views for the 4.8L, 5.3L, and 6.0L engine or Engine Control Module Connector End Views for the 6.6L (LLY) engine

1

Did you perform the Diagnostic System Check - Vehicle?

--

Go to Step 2

Go to Diagnostic System Check - Vehicle

2
  1. Disconnect C101.
  2. Connect a jumper wire between the signal circuit of the primary fuel level sender and the signal circuit of the secondary fuel level sender, female terminal side.
  3. Connect the J 33431-C Signal Generator and Instrument Panel Tester between the signal circuit of the fuel level sensor and the low reference circuit of the fuel level sensor on the female terminal side of the connector.
  4. Turn ON the ignition, with the engine OFF.

    5. Important: Verify the J 33431-C resistance settings with a DMM.

  5. Vary the resistance on the J 33431-C from 40-250 ohms.
  6. Refer to Fuel Level Specifications in order to convert from resistance to fuel gage display.

Does the fuel gage display the correct fuel level?

--

Go to Step 4

Go to Step 3

3

  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.

    3. Important: Verify the J 33431-C resistance settings with a DMM.

  3. Vary the resistance on the J 33431-C from 40-250 ohms.
  4. Refer to Fuel Level Specifications in order to convert from resistance to fuel level percentage.

    5. Important: Turn the ignition OFF momentarily between the resistance settings in order to quickly update the scan tool display.

  5. With the scan tool, observe one of the following fuel level parameters:
    6. • Fuel Tank Level Remaining % parameter in the powertrain control module (PCM) Enhanced EVAP data list - gas only.
    • Fuel Level Sensor % parameter in the Fuel data list - 6.6L diesel only.

Do the Fuel Level % parameters display the correct fuel level percentage?

--

Go to Step 11

Go to Step 5

4

Inspect for the following items:

    • A poor connection at the harness connector of the fuel level senders--Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs.
    • A high resistance in the primary and secondary signal circuits or the primary and secondary low reference circuits between the fuel level sender and C101
    • A misaligned fuel level sender
    • A deformed primary or secondary fuel tank

Did you find and correct the condition?

--

Go to Step 13

Go to Step 7

5

Test the signal circuits of the primary and secondary fuel level senders for a high resistance between C101 and the PCM. Refer to Circuit Testing and Wiring Repairs.

Did you find and correct the condition?

--

Go to Step 13

Go to Step 6

6

Test the low reference circuit of the primary and secondary fuel level senders for a high resistance between C101 and the PCM. Refer to Circuit Testing and Wiring Repairs.

Did you find and correct the condition?

--

Go to Step 13

Go to Step 9

7
  1. Remove the fuel level senders.
  2. Inspect for the following items:
    3. • The fuel level sender is stuck, perhaps due to an interference with the fuel strainer.
    • The fuel tank contains foreign material, for instance, ice.

Did you find and correct the condition?

--

Go to Step 13

Go to Step 8

8
  1. With the DMM, measure the resistance of the fuel level senders while moving the float arm.
  2. Observe both the analog and digital displays on the DMM.

Does the resistance change smoothly across the specified range?

40-250 ohms

Go to Diagnostic Aids

Go to Step 10

9

Inspect for poor connections at the harness connector of the PCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 13

Go to Step 12

10

Replace the fuel level sender. Refer to appropriate procedure:

    •  Fuel Level Sensor Replacement for the 4.3L engine
    •  Fuel Level Sensor Replacement for the 4.8L, 5.3L, and 6.0L engine
    •  Fuel Level Sensor Replacement for the 6.6L (LLY) engine

Did you complete the replacement?

--

Go to Step 13

--

11

Replace the instrument panel cluster (IPC). Refer to Control Module References for replacement, setup, and programming.

Did you complete the replacement?

--

Go to Step 13

--

12

Replace the PCM. Refer to Control Module References for replacement, setup, and programming.

Did you complete the replacement?

--

Go to Step 13

--

13

  1. Use the scan tool in order to clear the PCM DTCs.
  2. Operate the system in order to verify the repair.

Did you correct the condition?

--

System OK

Go to Step 2