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Test Description

WARNING: This page is about a different car, the 2004 Pontiac Grand Prix. However, it is still accessible from the selected car via links, so may be relevant.

The number(s) below refer to the step number(s) 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 PCM when you perform this diagnostic table.
Fuel Gage Inaccurate or Inoperative

Step Action Value(s) Yes No
Schematic Reference:  Instrument Cluster Schematics  
1 Did you perform the IPC Diagnostic System Check? - Go to Step 2  Go to Diagnostic System Check - Instrument Cluster 
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 and Equipment .
  3. Turn the ignition ON, with the engine OFF.
    4. IMPORTANT: Verify the J 33431-C  resistance settings with a DMM. See Special Tools and Equipment .
  4. Vary the resistance on the J 33431-C  from 40-250 Ω. See Special Tools and Equipment .
  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 the ignition ON, with the engine OFF.
    3. IMPORTANT: Verify the J 33431-C  resistance settings with a DMM. See Special Tools and Equipment .
  3. Vary the resistance on the J 33431-C  from 40-250 Ω. See Special Tools and Equipment .
  4. Refer to Fuel Level Specifications  in order to convert from resistance to fuel level percent.
    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 EVAP 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 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 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 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 Ω 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 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.
Did you complete the replacement?		 - Go to Step 13  -
11 Replace the IPC. Refer to Instrument Panel Cluster (IPC) Replacement .
Did you complete the replacement?		 - Go to Step 13  -
12
IMPORTANT: Program the replacement PCM.
Replace the PCM. Refer to Powertrain Control Module (PCM) Replacement in Engine Controls.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 
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