Diagnostic Test

CHECK FOR FUEL LEVEL SENSOR CIRCUIT DTCS
NOTE:
Diagnose and repair any CAN BUS, communication or implausible signal DTCs before proceeding with this test.

NOTE:
Excessive pressure build up or vacuum in the Evaporative system could possibly contribute to this DTC being set. Diagnose and repair any Evaporative System DTCs before continuing with this fault.
1. Turn the ignition on.
2. With the scan tool, read and record DTCs on the repair order.
  Are any Fuel Level Sensor Circuit DTCs present?
  
  Yes
  - Diagnose the appropriate Fuel Level Sensor Circuit DTCs before continuing.
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
  No
  - Go To 2
VISUALLY INSPECT FUEL TANK
1. Turn the ignition off.
2. Visually inspect the Fuel Tank for any obvious physical damage that may restrict the Fuel Level Sensor float from moving.
  Is the Fuel Tank damaged?
  
  Yes
  - Replace the Fuel Tank in accordance with the Service Information. Refer to TANK, FUEL, REMOVAL .
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
  No
  - Go To 3
EMPTY FUEL TANK AND CHECK THE FUEL LEVEL SENSOR READINGS
WARNING:
The fuel system is under a constant pressure (even with the engine off). Before testing or servicing any fuel system hose, fitting or line, the fuel system pressure must be released. Failure to follow these instructions can result in possible serious or fatal injury.
1. Turn the ignition off.
2. Drain the fuel tank in accordance with the Service Information. Refer to DRAINING FUEL TANK .
3. Turn the ignition on.
  NOTE:
  If the Fuel Tank is completely empty, the Fuel Level Sensor should read at or near empty (indicated by a voltage reading of approximately 4.3-4.5 volts).
4. With the scan tool, read the voltage for the Fuel Level Sensor.
  Is the Fuel Level Sensor reading at or near empty?
  
  Yes
  - Go To 4
  No
  - Go To 5
REFILL FUEL TANK AND CHECK THE FUEL LEVEL SENSOR READINGS
NOTE:
Make sure that you have enough fuel to put into the vehicle to make a good determination of the Fuel Level Sensor voltage feedback. It may be necessary to add more fuel to what was removed to do so.
1. While monitoring the Fuel Level Sensor voltage reading on scan tool, begin putting fuel back into the Fuel Tank.
2. With the scan tool, read the voltages for the Fuel Level Sensor.
  NOTE:
  The Fuel Level Sensor voltage should decrease as fuel is added at a steady rate. Watch for the voltage to momentarily pause or stop moving while fuel is being added indicating a bad spot on the sensor or a temporary restriction to the movement of the float arm.
  
  Does the voltage for the Fuel Level Sensor change smoothly without any pause while fuel was added?
  
  Yes
  - Go To 6
  No, Fuel Level Sensor voltage does not decrease correctly
  - Go To 5
INTERNAL INSPECTION OF THE FUEL TANK
WARNING:
The fuel system is under a constant pressure (even with the engine off). Before testing or servicing any fuel system hose, fitting or line, the fuel system pressure must be released. Failure to follow these instructions can result in possible serious or fatal injury.
1. Remove the Fuel Tank in accordance with the Service Information. Refer to TANK, FUEL, REMOVAL .
2. Remove the Fuel Pump Module. Refer to MODULE, FUEL PUMP, REMOVAL .
3. Visually inspect the inside of the Fuel Tank for any obstructions or deformities.
4. Inspect the Primary Fuel Level Sensor Float arm for damage.
  Were any problems found?
  
  Yes
  - Repair or replace as necessary.
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
  No
  - Replace the Primary Fuel Level Sensor in accordance with the Service Information.
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
CHECK RELATED BCM AND COMPONENT CONNECTIONS
1. Disconnect all BCM harness connectors.
2. Disconnect all related in-line harness connections (if equipped).
3. Disconnect the related component harness connectors.
4. Inspect harness connectors, component connectors, and all male and female terminals for the following conditions:
  - Proper connector installation.
  - Damaged connector locks.
  - Corrosion.
  - Other signs of water intrusion.
  - Weather seal damage (if equipped).
  - Bent terminals.
  - Overheating due to a poor connection (terminal may be discolored due to excessive current draw).
  - Terminals that have been pushed back into the connector cavity.
  - Check for spread terminals and verify proper terminal tension.
  Repair any conditions that are found.
5. Reconnect all BCM harness connectors. Be certain that all harness connectors are fully seated and the connector locks are fully engaged.
6. Reconnect all in-line harness connectors (if equipped). Be certain that all connectors are fully seated and the connector locks are fully engaged.
7. Reconnect all related component harness connectors. Be certain that all connectors are fully seated and the connector locks are fully engaged.
8. With the scan tool, erase DTCs.
9. Test drive or operate the vehicle in accordance with the when monitored and set conditions.
10. With the scan tool, read DTCs.
  Did the DTC return?
  
  Yes
  - Replace and program the Body Control Module (BCM) in accordance with the Service Information. Refer to MODULE, BODY CONTROL (BCM), REMOVAL .
  - Perform the BODY VERIFICATION TEST. Refer to BODY VERIFICATION TEST .
  No
  - The wiring or poor connection problem has been repaired.
  - Perform the BODY VERIFICATION TEST. Refer to BODY VERIFICATION TEST .