GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2000 🢒 Blazer - 4WD 🢒 Body and Accessories 🢒 Instrument Panel, Gauges, and Console 🢒 Fuel Gage Inaccurate or Inoperative

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 in Wiring Systems.

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 be set in the PCM (2.2L)/VCM (4.3L) when you perform this diagnostic table.

Step

Action

Value(s)

Yes

No

Schematic Reference: Instrument Cluster: Analog Schematics

1

Did you perform the Instrument Cluster Diagnostic System Check?

--

Go to Step 2

Go to Diagnostic System Check - Instrument Cluster

2
  1. Disconnect C104.
  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 male terminal side of the connector.
  3. Turn the ignition ON , 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.

Does the fuel gage move from approximately empty to approximately full?

--

Go to Step 4

Go to Step 3

3

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

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

  3. Vary the resistance on J 33431-C the from 40-250 ohms.

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

  4. With the scan tool, observe the Fuel Level parameter in the PCM EVAP data list.

Does the Fuel Level parameter change from approximately 0 % to approximately 100 %?

--

Go to Step 11

Go to Step 5

4

Inspect for the following items:

    • A high resistance in the signal circuit or the low reference circuit of the fuel level sensor between C104 and the fuel level sensor.
    • A poor connection at the harness connector of the fuel level sensor
        Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems.
    • 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 sensor for a high resistance. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems.

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 sensor for a high resistance. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems.

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. • A stuck fuel level sender (i.e. the fuel strainer interfering with the sender float arm)
    • Foreign material in the fuel tank (ice)

Did you find and correct the condition?

--

Go to Step 13

Go to Step 8

8
  1. With the J 39200 DMM, measure the resistance of the fuel level sensor 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 (2.2L/VCM (4.3L). Refer to Testing for Intermittent Conditions and Poor Connections and to 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 sensor. Refer to the appropriate procedure:

    •  Fuel Level Sensor Replacement in Engine Controls - 2.2L.
    •  Fuel Level Sensor Replacement in Engine Controls - 2.2L (L43).
    •  Fuel Level Sensor Replacement in Engine Controls - 4.3L.

Did you complete the replacement?

--

Go to Step 13

--

11

Replace the IPC. Refer to Instrument Cluster Replacement .

Did you complete the replacement?

--

Go to Step 13

--

12

Important: Program the replacement PCM/VCM.

Replace the PCM/VCM. Refer to the appropriate procedure:

    •  Powertrain Control Module Replacement/Programming in Engine Controls - 2.2L.
    •  Powertrain Control Module Replacement/Programming in Engine Controls - 2.2L (L43).
    •  VCM Replacement/Programming in Engine Controls - 4.3L.

Did you complete the replacement?

--

Go to Step 13

--

13

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

Did you correct the condition?

--

System OK

Go to Step 2