GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Buick 🢒 2007 🢒 Rendezvous - FWD 🢒 Diagnostic Navigation 🢒 Vehicle Diagnostic Information 🢒 Fuel Gage Inaccurate or Inoperative

Diagnostic Instructions
    • Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
    • Review Strategy Based Diagnosis for an overview of the diagnostic approach.
    •  Diagnostic Procedure Instructions provides an overview of each diagnostic category.

Circuit/System Description

The fuel level sensor changes resistance in response to the fuel level. The powertrain control module (PCM) monitors the signal circuit of the fuel level sensor in order to determine the fuel level. When the fuel tank is full, the sensor resistance is low and the PCM senses a low signal voltage. When the fuel tank is empty, the sensor resistance is high and the PCM senses a high signal voltage. The PCM uses the signal circuit of the fuel level sensor in order to calculate the percentage of remaining fuel in the tank. The PCM sends the fuel level percentage via serial data to the instrument panel cluster (IPC) in order to display the fuel gage. The fuel information is also used for misfire and evaporative emission (EVAP) diagnostics.

Reference Information

Schematic Reference

    •  Instrument Cluster Schematics
    •  Engine Controls Schematics

Connector End View Reference

    •  Displays and Gages Connector End Views
    •  Powertrain Control Module Connector End Views

Description and Operation

    •  Instrument Cluster Description and Operation
    •  Powertrain Control Module Description
    •  Fuel System Description

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

Scan Tool Reference

    •  Scan Tool Data List
    •  Scan Tool Data Definitions

Circuit/System Testing
  1. Ignition OFF, disconnect the harness connectors at the fuel level sensor.
  2. Ignition OFF, test for less than 1.0 ohm of resistance between the low reference circuit terminal and ground.
    3. ⇒If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the PCM.
  3. Install a Signal Generator and Instrument Panel Tester between the signal circuit terminal and ground.
  4. Ignition ON, vary the signal generator resistance between 40 and 250 ohms. Verify that the scan tool Fuel Tank Level Remaining parameter displays a range that varies between 5 and 95 percent as the signal generator resistance changes.
    5. ⇒If not displaying the specified range, test the signal circuit for an open/high resistance. If the circuits test normal, replace the PCM.
  5. Vary the signal generator resistance between 40 and 250 ohms. Verify that the fuel gage displays a range that varies between empty and full as the signal generator resistance changes.
    6. ⇒If not displaying the specified range, replace the IPC.
  6. If all circuits test normal, test or replace the fuel level sensor.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Fuel Level Sensor Replacement
    •  Control Module References for PCM and IPC replacement, setup, and programming