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Test Description

WARNING: This page is about a different car, the 2004 Pontiac Aztek and 2004 Buick Rendezvous. 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 sender.
  2. 13:  DTCs will be set in the engine control module (ECM)/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  
1 Did you perform the Diagnostic System Check - Instrument Cluster? - Go to Step 2  Go to Diagnostic System Check - Instrument Cluster 
2
  1. Disconnect C305/C305C.
  2. Connect the J 33431-C  Signal Generator and Instrument Panel Tester between the signal circuit of the fuel level sender and the low reference circuit of the fuel level sender (male terminal side). See Special Tools and Equipment .
  3. Turn ON the ignition, 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 ohms. 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 ON the ignition, 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 ohms. See Special Tools and Equipment .
  4. Refer to Fuel Level Specifications  in order to convert from resistance to fuel level percent or voltage.
    5. IMPORTANT: Turn OFF the ignition momentarily between the resistance settings in order to quickly update the scan tool display.
  5. With the scan tool, observe the Fuel Level Sensor parameter in the ECM/PCM EVAP Data, data list.
Does the scan tool display the correct fuel level percent or voltage?		 - 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 sender 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 sender 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 sender.
  2. Inspect for the following items:
    • 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 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 Ω Go to Diagnostic Aids Go to Step 10 
9 Inspect for poor connections at the harness connector of the engine control module (ECM)/powertrain control module (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 Fuel Level Sensor Replacement (Prior to VIN 4S558922 (100mm Sender)) or Fuel Level Sensor Replacement (VIN 4S558922 and Later (130mm Sender)) in Engine Controls - 3.4L or Fuel Level Sensor Replacement in Engine Controls - 3.6L (LY7).
Did you complete the replacement?		 - Go to Step 13  -
11
IMPORTANT: Perform the compass calibration and variance procedure on the replacement instrument panel cluster (IPC).
Replace the IPC. Refer to Instrument Panel Cluster (IPC) Replacement .Did you complete the replacement?		 - Go to Step 13  -
12
IMPORTANT: Program the replacement ECM/PCM.
Replace the ECM/PCM. Refer to Powertrain Control Module (PCM) Replacement in Engine Controls - 3.4L or Engine Control Module (ECM) Replacement in Engine Controls - 3.6L (LY7).Did you complete the replacement?		 - Go to Step 13  -
13 
  1. Use the scan tool in order to clear the ECM/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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