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

PINPOINT TEST Y: 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 cluster 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 instrument cluster does not receive the check fuel cap message and the check fuel cap indicator remains off.

If the instrument cluster does not receive the fuel cap off data from the PCM for 5 seconds or less, the instrument cluster defaults the check fuel cap indicator to the last setting, based upon the last known good data message. If the instrument cluster does not receive the fuel cap off data from the PCM for more than 5 seconds, the instrument cluster sets DTC U0100 in continuous memory and defaults the fuel cap off indicator off.

NOTE: If DTC U0100 is set in the instrument cluster, other observable symptoms may be an inoperative speedometer, temperature gauge (except Hybrid) or odometer.

- 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 454 g (1.0 lb) per minute.

This pinpoint test is intended to diagnose the following:
- PCM
- Instrument cluster

Y1:

Y2-Y5: