Test Procedure

QH1 PRELIMINARY DIAGNOSIS

NOTE: Diagnostic trouble code (DTC) P115A may set with a low fuel level input. If an excessively low fuel level input message is received by the PCM from the instrument cluster, the PCM will limit the injection control pressure (ICP). This may cause a lack of power, rough idle, or other driveability concerns. If no additional DTCs are present, the concern may have been caused by the vehicle running too low on fuel.

Possible causes:
- fuel tank empty
- fuel tank overfilled
- fuel control module circuitry
- fuel control module
- instrument cluster
- PCM
Key ON, engine OFF.
Access the instrument cluster.
Carry out self-test diagnostics for the instrument cluster.
Carry out the PCM self-test.

Are any instrument cluster DTCs present or any additional PCM DTCs present?

Yes	No
For instrument cluster DTCs, REFER to INSTRUMENT CLUSTER to continue diagnosis. For additional PCM DTCs, REFER to DIAGNOSTIC TROUBLE CODE (DTC) DESCRIPTIONS .	GO to QH2.

QH2 CHECK THE INSTRUMENT CLUSTER FLI PID

Access and record the instrument cluster FLI PID.
Compare the instrument cluster FLI PID recorded value to the instrument cluster fuel gauge.

Does the instrument cluster FLI PID correspond to the fuel gauge level?

Yes	No
GO to QH3.	REFER to INSTRUMENT CLUSTER to continue diagnosis of the fuel level.

QH3 CHECK THE PCM FLI PID

Access and record the PCM FLI PID.
Compare the PCM FLI PID recorded value to the instrument cluster FLI PID recorded value.

Does the PCM FLI PID correspond to the instrument cluster FLI PID?

Yes	No
UNABLE to duplicate the condition. CHECK for a loose connection, and damaged or corroded terminals. WIGGLE the harness attempting to recreate the fault. REPAIR as necessary. REFER to SYMPTOM CHARTS - 6.0L DIESEL if a driveability concern exists.	CLEAR the DTCs. REPEAT the self-test. If the DTC is present again, INSTALL a new PCM.