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

Instrumentation, Message Center and Warning Chimes

Pinpoint Test H: The Check Fuel Cap Warning 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 (IC) a message over the communication network to turn on the check fuel cap warning indicator. The PCM only sets DTC P0457 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 fuel cap status and the check fuel cap warning indicator 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 454 g (1.0 lb) per minute.

This pinpoint test is intended to diagnose the following:

- PCM
- IC



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

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H1 CARRY OUT THE IC INDICATOR LAMP CONTROL ACTIVE COMMAND USING THE SCAN TOOL


- Ignition ON.
- Enter the following diagnostic mode on the scan tool: IC DataLogger.
- Select the IC all warning lamps (ALL_LAMP) active command 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 H2.

No
INSTALL a new IC. REFER to Instrument Cluster (IC) Instrument Cluster (IC). TEST the system for normal operation.

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H2 RETRIEVE THE RECORDED DTCs FROM PCM KOEO SELF-TEST


- Check for recorded PCM DTCs from the Key ON Engine OFF (KOEO) self-test.
- 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. TEST the system for normal operation.

No
If the check fuel cap indicator is always on, INSTALL a new PCM. 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 IC to turn on the check fuel cap warning indicator.

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