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 THE FUEL TANK FOR DAMAGE
1. Turn the ignition off.
2. Visually inspect the Fuel Tank for any obvious physical damage that may restrict the Fuel Sending Unit float from moving.
  Is the Fuel Tank damaged?
  
  Yes
  - Replace the Fuel Tank in accordance with the Service Information. Refer to 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, both Fuel Level Sensors 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 Fuel Level Sensor 1 and Fuel Level Sensor 2.
  Are both Fuel Level Sensors reading at or near empty?
  
  Yes
  - Go To 4
  No, Fuel Level Sensor 1 is not reading empty
  - Go To 5
  No, Fuel Level Sensor 2 is not reading empty
  - Go To 6
REFILL FUEL TANK AND CHECK THE FUEL LEVEL SENSOR READINGS
NOTE:
Make sure that you have enough fuel to put into the vehicle to overflow into the secondary tank. It may be necessary to add more fuel to what was removed to do so.
1. While monitoring the Fuel Level Sensor voltage readings on scan tool, begin putting fuel back into the Fuel Tank.
2. With the scan tool, read the voltages for Fuel Level Sensor 1 and Fuel Level Sensor 2.
  NOTE:
  The Primary Fuel Level Sensor voltage should decrease as fuel is added until it reaches near full. As fuel starts to overflow to the secondary tank, the Secondary Fuel Level Sensor voltage should also start to decrease.
  
  Does the voltage for both Fuel Level Sensors change as described above?
  
  Yes
  - Go To 7
  No, Fuel Level Sensor 2 voltage does not decrease correctly
  - Go To 6
  No, Fuel Level Sensor 1 voltage does not decrease correctly
  - Go To 5
PERFORM AN INTERNAL INSPECTION OF THE PRIMARY FUEL TANK
1. Remove or lower the Fuel Tank in accordance with the Service Information. Refer to REMOVAL .
2. Remove the Primary Fuel Pump Module.
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. Refer to MODULE, FUEL PUMP, REMOVAL .
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
PERFORM AN INTERNAL INSPECTION OF THE SECONDARY FUEL TANK
1. Remove or lower the Fuel Tank in accordance with the Service Information. Refer to REMOVAL .
2. Remove the Secondary Fuel Pump Module. Refer to MODULE, FUEL PUMP, REMOVAL .
3. Visually inspect the Siphon Tube for any obstructions, cracks or loose connections.
4. Inspect the Secondary Fuel Level Sensor Float arm for damage.
  Were any problems found?
  
  Yes
  - Repair the float arm or siphon tube, or replace the Fuel Tank Assembly in accordance with the service information.
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
  No
  - Replace the Secondary Fuel Level Sensor and Siphon Pump Assembly in accordance with the service information.
    NOTE:
    If the Siphon Pump Assembly or Siphon Tube are at fault, check the fuel and Fuel Tank for dirt or contamination. Even a small amount of dirt in the fuel can damage a Siphon Pump or Tube.
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
CHECK RELATED PCM AND COMPONENT CONNECTIONS
1. Perform any Service Bulletins that apply.
2. Disconnect all PCM harness connectors.
3. Disconnect all related in-line harness connections (if equipped).
4. Disconnect the related component harness connectors.
5. 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.
6. Reconnect all PCM harness connectors. Be certain that all harness connectors are fully seated and the connector locks are fully engaged.
7. Reconnect all in-line harness connectors (if equipped). Be certain that all connectors are fully seated and the connector locks are fully engaged.
8. Reconnect all related component harness connectors. Be certain that all connectors are fully seated and the connector locks are fully engaged.
9. With the scan tool, erase DTCs.
10. Test drive or operate the vehicle in accordance with the when monitored and set conditions.
11. With the scan tool, read DTCs.
  Did the DTC return?
  
  Yes
  - Replace and program the Powertrain Control Module (PCM) in accordance with the Service Information. Refer to MODULE, POWERTRAIN CONTROL (PCM), REMOVAL .
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
  No
  - The wiring or poor connection problem has been repaired.
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .