Pinpoint Tests AI: The Check Fuel Cap Message Is Inoperative/Always On

Instrumentation, Message Center and Warning Chimes

Pinpoint Tests

Pinpoint Test AI: The CHECK FUEL CAP Message Is Inoperative/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 Cluster (IC) a message over the communication network to turn on the CHECK FUEL CAP message. 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 IC does not receive the check fuel cap message and the CHECK FUEL CAP message remains 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
- IC



PINPOINT TEST AI: THE CHECK FUEL CAP MESSAGE IS INOPERATIVE/ALWAYS ON

-------------------------------------------------
AI1 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 message is displayed, REFER to Computers and Control Systems Information.

If the CHECK FUEL CAP message is not displayed, INSTALL a new PCM. TEST the system for normal operation.

No
If the CHECK FUEL CAP message is always displayed, INSTALL a new IC. REFER to Instrument Cluster (IC) Instrument Cluster (IC). TEST the system for normal operation.

If the CHECK FUEL CAP message is not displayed, 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 IC to turn on the check fuel cap warning indicator.

-------------------------------------------------