Pinpoint Tests AI: The Check Fuel Cap Indicator Is Never/Always On

Instrumentation, Message Center and Warning Chimes

Pinpoint Tests


Pinpoint Test AI: The Check Fuel Cap Indicator Is Never/Always On

Normal Operation

The PCM monitors the fuel tank evaporative emission system for significant leaks that occur following refueling of the vehicle. Once the PCM detects a fuel vapor leak, the PCM sends the Instrument Panel Cluster (IPC) a message over the communication network to turn on the check fuel cap indicator. DTC P0457 sets in the PCM following a successful cruise test, which is initiated when the vehicle is driven at a steady speed above 64 km/h (40 mph) for a duration of approximately 4-5 minutes. If the PCM is unable to successfully run the cruise test, the IPC does not receive the check fuel cap message and the check fuel cap indicator remains off.

If the IPC does not receive the fuel cap off data from the PCM for 5 seconds or less, the IPC defaults the check fuel cap indicator to the last setting, based upon the last known good fuel cap off message received.

If the IPC does not receive the fuel cap off data from the PCM for more than 5 seconds, the IPC sets DTC U0100:87 in continuous memory and defaults the check fuel cap indicator off.

- DTC P0457 (Evaporative Emission System Leak Detected (fuel cap loose/off)) - sets in the PCM if a fuel tank pressure change greater than -23.7 kPa (-7 in-Hg) of vacuum within 30 seconds after refueling occurs, or there is an excessive purge (fuel vapor) flow of greater than 454g (1.0lb) per minute.

This pinpoint test is intended to diagnose the following:

- PCM
- IPC



PINPOINT TEST AI: THE CHECK FUEL CAP INDICATOR IS NEVER/ALWAYS ON

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AI1 CARRY OUT THE IPC INDICATOR LAMP CONTROL ACTIVE COMMAND USING THE SCAN TOOL


- Ignition ON.
- Enter the following diagnostic mode on the scan tool: IPC DataLogger.
- Select the IPC check fuel cap indicator (FUEL_CAP) active command. Command the check fuel cap indicator on and off. Observe the check fuel cap indicator.
- Does the check fuel cap indicator illuminate when commanded on, and turn off when commanded off?

Yes
GO to AI2.

No
INSTALL a new IPC. REFER to Instrument Panel Cluster (IPC) Service and Repair. TEST the system for normal operation.

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AI2 RETRIEVE THE RECORDED DTCs FROM BOTH CONTINUOUS AND ON-DEMAND PCM SELF-TESTS


- Check for recorded PCM DTCs from the continuous and on-demand self-tests.
- Is DTC P0457 recorded?

Yes
If the check fuel cap indicator is illuminated, REFER to Computers and Control Systems Information.

If the check fuel cap indicator is not illuminated, INSTALL a new PCM. REFER to Computers and Control Systems. TEST the system for normal operation.

No
If the check fuel cap indicator is always on, INSTALL a new IPC. REFER to Instrument Panel Cluster (IPC) Service and Repair.
TEST the system for normal operation.

If the check fuel cap indicator is not illuminated, the system is operating normally at this time. If the fuel cap was left off and the check fuel cap warning indicator did not turn on, driving conditions may not have allowed for the PCM to run the cruise test and message the IPC to turn on the check fuel cap warning indicator.

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