U1403

U1403-IMPLAUSIBLE FUEL LEVEL SIGNAL





For a complete wiring diagram Consult Diagrams/Electrical.

- When Monitored:
Ignition on.

- Set Condition:
The fuel level message the PCM is receiving is implausible. The circuit is continuously monitored. One trip fault.





Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Initial Inspection and Diagnostic Overview.

Theory of Operation

The Front Control Module isn't receiving a fuel level signal over CAN B from the Cluster Module. The FCM has to send the PCM a fuel level signal over CAN C. The signal the FCM sends over CAN C is implausible.

Diagnostic Test

1. ACTIVE DTC
Ignition on, engine not running.
With a scan tool, select View DTCs.
Is the DTC Active at this time?

Yes

- Go To 2

No

- Refer to the INTERMITTENT CONDITION Diagnostic Procedure. Intermittent Condition.

2. CAN B OR CAN C BUS HARDWARE DTCS ALSO ACTIVE
With a scan tool check for DTCs in the FCM.
Are any CAN B or CAN C Hardware related DTCs active at this time?

Yes

- (Refer to Communications Test for this DTC and/or Manufacturer Code Charts) for the appropriate diagnostic procedures.
- Perform BODY VERIFICATION TEST - VER 1.Body Verification Test.

No

- Go To 3

3. (N4) FUEL LEVEL SIGNAL CIRCUIT OPEN




Turn the ignition off.
Disconnect the Fuel Pump Module harness connector.
Disconnect the C2 Cluster harness connectors.
Measure the resistance of the (N4) Fuel Level Signal circuit from the Fuel Pump Module harness connector to the C2 Cluster harness connector.
Is the resistance below 5.0 ohms?

Yes

- Go To 4

No

- Repair the open in the (N4) Fuel Level Signal circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

4. (N4) FUEL LEVEL SIGNAL CIRCUIT SHORTED TO GROUND




Measure the resistance between ground and the (N4) Fuel Level Signal circuit in the Fuel Pump Module harness connector.
Is the resistance below 100 ohms?

Yes

- Repair the short to ground in the (N4) Fuel Level Signal circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Go To 5

5. (N5) FUEL LEVEL SENSOR RETURN CIRCUIT OPEN




Measure the resistance of the (N5) Fuel Level Sensor Return circuit from the Fuel Pump Module harness connector to the C2 Cluster harness connector.
Is the resistance below 5.0 ohms?

Yes

- Go To 6

No

- Repair the open in the (N5) Fuel Level Sensor Return circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

6. (N4) FUEL LEVEL SIGNAL CIRCUIT SHORTED TO THE (N5) FUEL LEVEL SENSOR RETURN CIRCUIT




Measure the resistance between the (N4) Fuel Level Signal circuit and the (N5) Fuel Level Sensor Return circuit in the Fuel Pump Module harness connector.
Is the resistance below 5.0 ohms?

Yes

- Repair the short between the (N5) Fuel Level Sensor Return circuit and the (N4) Fuel Level Signal circuit.
- Perform BODY VERIFICATION TEST-VER 1. Body Verification Test.

No

- Go To 7

7. PCM
NOTE: Before continuing, check the PCM harness connector terminals for corrosion, damage, or terminal push out. Repair as necessary.

Using the schematics as a guide, inspect the wire harness and connectors. Pay particular attention to all Power and Ground circuits.
Were there any problems found?

Yes

- Repair as necessary.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Replace and program the Powertrain Control Module.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.