Diagnostic Test

WARNING: This page is about a different variant/trim than selected.

READ AND RECORD DTCS AND ENVIRONMENTAL DATA - ERASE DTCS AND CHECK FOR THE DTC TO RETURN
1. With the scan tool, read DTCs in all Electronic Control Units (ECUs) and record on the repair order.
2. For future reference, with the scan tool, run and save a vehicle Scan Report and all related recorded data.
3. With the scan tool, erase all DTCs.
4. Turn the ignition off for a minimum of 10.0 seconds.
5. Turn the ignition on.
6. Using the When Monitored and Set Conditions above and recorded data, operate the vehicle in the conditions that set the DTC.
7. With the scan tool, read DTCs.
Did the DTC return?

Yes
- Go To 2
No
- Perform the INTERMITTENT CONDITION diagnostic procedure. Refer to INTERMITTENT CONDITION .
MONITOR THE FUEL LEVEL SENSOR VOLTAGE READING FOR AN OPEN SPOT ON THE SENSOR
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. Disconnect the fuel supply line at the fuel rail.
2. Connect a drain hose between the fuel supply line and an approved fuel container.
3. Turn the ignition on.
4. Remove the Fuel Pump Relay from the PDC.
5. Connect a jumper across terminal 30 and terminal 87 of the Fuel Pump Relay connector to actuate the Fuel Pump Assembly until all fuel is removed from the Fuel Tank.
6. Remove the jumper when there is no more fuel coming out of the hose.
  NOTE:
  When 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) on the scan tool. If the Fuel Tank is near full, the scan tool should read approximately 0.5 volts on the scan tool.
  
  NOTE:
  Make sure that you have enough fuel to put back 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 in order to do so.
7. While monitoring the Fuel Level Sensor voltage reading on scan tool, begin putting fuel back into the Fuel Tank.
  NOTE:
  The Fuel Level Sensor voltage should decrease as fuel is added at a steady rate. Watch for the voltage to change suddenly while fuel is being added. If the voltage suddenly changes to or near 5.0 volts, it would indicate a bad spot (open) on that portion of the sensor.
  
  Did the Fuel Level Sensor reading suddenly change to 5.0 volts at any time while adding fuel?
  
  Yes
  - Replace the Fuel Level Sensor in accordance with the Service Information. Refer to SENDING UNIT AND SENSOR, FUEL LEVEL, REMOVAL AND INSTALLATION .
  - Perform the PCM VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
  No
  - Perform the INTERMITTENT CONDITION diagnostic procedure. Refer to INTERMITTENT CONDITION .
CHECK THE FUEL LEVEL SENSOR (N4) POSITION SIGNAL CIRCUIT VOLTAGE
NOTE:
Do not disconnect the Fuel Pump Assembly harness connector during this step. The sensor is powered by a voltage close to the vehicle Battery (minus a diode voltage drop). If disconnected, the voltage reading on the Fuel Level Sensor Signal circuit will be equal to source voltage which is approximately Battery voltage.
1. Back probe and measure the voltage on the Fuel Level Sensor (N4) Position Signal circuit at the Fuel Pump Assembly harness connector.
  What is the voltage reading?
  
  Source voltage (approximately 12.0 volts):
  - Go To 5
  Zero volts:
  - Go To 4
ISOLATE AND CHECK THE FUEL LEVEL SENSOR (N4) POSITION SIGNAL CIRCUIT FOR AN OPEN/HIGH RESISTANCE
1. The ignition must be off when checking the continuity of a circuit.
2. Isolate the circuit by disconnecting the Electronic Control Unit (ECU) and the component harness connector containing the circuit being tested. Note: Use the wiring diagram as a guide to follow the path of the circuit.
3. Before measuring the resistance of any circuit, first measure the resistance between the two leads of the DVOM. Note: The meter leads can add resistance to the measurement value.
4. Connect one lead of the DVOM to the circuit being tested at the component harness connector.
5. Connect the other lead to the circuit being tested at the ECU harness connector and measure the resistance of the circuit.
Is the resistance below 3.0 Ohms?

Yes
- Go To 8
No
- Repair the circuit for an open or high resistance.
- Perform the BODY VERIFICATION TEST. Refer to BODY VERIFICATION TEST .
CHECK THE VOLTAGE AT THE (G109) SENSOR RETURN CIRCUIT
NOTE:
Leave the Fuel Pump Assembly harness connector plugged in during this step also.
1. Back probe and measure the voltage on the (G109) Sensor Return circuit at the Fuel Pump Assembly harness connector.
  What is the voltage reading?
  
  Source voltage (approximately 12.0 volts):
  - Go To 7
  Zero volts:
  - Go To 6
CHECK THE FUEL LEVEL SENSOR (N4) POSITION SIGNAL CIRCUIT FOR A SHORT TO ANOTHER VOLTAGE SUPPLY
1. Turn the ignition off.
2. Disconnect the Fuel Pump Assembly harness connector.
3. Disconnect the BCM C6 harness connector.
4. Check for continuity between the Fuel Level Sensor (N4) Position Signal circuit and all other circuits at the BCM C6 harness connector.
  Is there continuity between the Fuel Level Sensor (N4) Position Signal circuit and any other circuit?
  
  Yes
  - Repair the Fuel Level Sensor (N4) Position Signal circuit for a short to the circuit that showed continuity.
  - Perform the BODY VERIFICATION TEST. Refer to BODY VERIFICATION TEST .
  No
  - Replace the Fuel Level Sensor in accordance with the Service Information. Refer to SENDING UNIT AND SENSOR, FUEL LEVEL, REMOVAL AND INSTALLATION .
  - Perform the BODY VERIFICATION TEST. Refer to BODY VERIFICATION TEST .
ISOLATE AND CHECK THE (G109) SENSOR RETURN CIRCUIT FOR AN OPEN/HIGH RESISTANCE
1. The ignition must be off when checking the continuity of a circuit.
2. Isolate the circuit by disconnecting the Electronic Control Unit (ECU) and the component harness connector containing the circuit being tested. Note: Use the wiring diagram as a guide to follow the path of the circuit.
3. Before measuring the resistance of any circuit, first measure the resistance between the two leads of the DVOM. Note: The meter leads can add resistance to the measurement value.
4. Connect one lead of the DVOM to the circuit being tested at the component harness connector.
5. Connect the other lead to the circuit being tested at the ECU harness connector and measure the resistance of the circuit.
Is the resistance below 3.0 Ohms?

Yes
- Go To 8
No
- Repair the circuit for an open or high resistance.
- Perform the BODY VERIFICATION TEST. Refer to BODY VERIFICATION TEST .
CHECK RELATED BCM AND COMPONENT CONNECTIONS
1. Perform any Service Bulletins that apply.
2. Disconnect all BCM 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 BCM 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 the Body Control Module in accordance with the Service Information. Refer to MODULE, BODY CONTROL (BCM), REMOVAL AND INSTALLATION .
  - Perform the BODY VERIFICATION TEST. Refer to BODY VERIFICATION TEST .
  No
  - Perform the BODY VERIFICATION TEST. Refer to BODY VERIFICATION TEST .
  - Test complete.