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Home >> Buick >> 2007 >> Lucerne CX >> Repair and Diagnosis >> External Pages >> Different car >> Section 95 (Instrument Panel System Displays, Gauges And Console) >> Diagnostic Information and Procedures >> Fuel Gage Inaccurate or Inoperative >> Test Description

Test Description

WARNING: This page is about a different car, the 2006 Buick LaCrosse and 2006 Buick Allure. However, it is still accessible from the selected car via links, so may be relevant.

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

  1. 3:  This step tests for a high resistance in the signal circuit and the low reference circuit of the fuel level sensor.
  2. 13:  DTCs will be set in the powertrain control module (PCM) when you perform this diagnostic table.
Fuel Gage Inaccurate or Inoperative

Step Action Value(s) Yes No
Schematic Reference: Instrument Cluster Schematics 
Connector End View Reference: Powertrain Control Module (PCM) Connector End Views in Engine Controls - 3.8L, Engine Control Module (ECM) Connector End Views in Engine Controls - 3.6L or Inline Harness Connector End Views in Wiring Systems
1 Did you perform the Diagnostic System Check - Vehicle? - Go to Step 2  Go to Diagnostic System Check - Vehicle in Vehicle DTC Information
2
  1. Disconnect the fuel level sensor.
  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. See Special Tools .
  3. Turn ON the ignition, with the engine OFF.
    4. IMPORTANT: Verify the J 33431-C  resistance settings with a DMM. See Special Tools .
  4. Vary the resistance on the J 33431-C  from 40-250 ohms. See Special Tools .
  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. See Special Tools .
  3. Vary the resistance on the J 33431-C  from 40-250 ohms. See Special Tools .
  4. Refer to Fuel Level Specifications  in order to convert from resistance to the fuel level remaining.
    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 the Fuel Tank Level Remaining parameter in the PCM/ECM evaporative emission (EVAP) Data List or the PCM/ECM IPC Data List.
Does the Fuel Level Remaining parameter display the correct fuel level percentage?		 - Go to Step 11  Go to Step 5 
4 Inspect for the following items:
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 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 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 sensor.
  2. Inspect for the following items:
    • A stuck fuel level sensor, i.e. the fuel strainer interfering with the sender float arm.
    • Foreign material in the fuel tank, i.e. 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 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 Ω Go to Diagnostic Aids Go to Step 10 
9 Inspect for poor connections at the harness connector of the powertrain control module (PCM)/engine control module (ECM). 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 sensor. Refer to Fuel Level Sensor Replacement in Engine Controls - 3.8L or to Fuel Level Sensor Replacement in Engine Controls - 3.6L.
Did you complete the replacement?		 - Go to Step 13  -
11 Replace the instrument panel cluster (IPC). Refer to Control Module References in Computer/Integrating Systems for replacement, setup and programming.
Did you complete the replacement?		 - Go to Step 13  -
12 Replace the PCM/ECM. Refer to Control Module References in Computer/Integrating Systems 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/ECM DTCs.
  2. Operate the system in order to verify the repair.
Did you correct the condition?		 - System OK Go to Step 2 
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