Dodge 2004 Neon SX2 Diagnostic Manual page 343

elapsed. There is a limit on the total amount of run
time that is applied to the one-week timer. There is
also a limit on the total soak time that will be
allowed to be applied to the one-week timer. There
will be a limit on the amount of accrued run time
during one specific drive that can be applied to the
one-week timer.
The enabling criteria to run this monitor are:
• Fuel level less than 85%
• Ambient temperature greater than 40 °F (4.4 °C)
Rationality Tests
1. The rationality check of the switch, solenoid and
seal will be performed as follows:
• At key-on, the NVLD solenoid will be energized to
vent any vacuum that may be trapped in the
evaporative system from the previous soak. This
should result in an open switch condition.
• The solenoid will be de-energized (to seal the
system) at the point where purge begins. The
system / NVLD component rationality passes for
that drive cycle if the switch closes after purge
begins.
• The solenoid is then re-energized for the remain-
der of the drive cycle.
•
If the switch events are not seen in a certain
period of time, the rationality check will have
failed (2 trip rule).
2. Purge Flow:
The above rationality check is considered suffi-
cient to confirm purge solenoid function and con-
formance with the purge flow test requirement. The
Purge Flow Monitor is passed based on switch
activity when purge is turned on or based on a rich
fuel control shift when purge is turned on.
GENERAL INFORMATION
Medium and Large Leak Test (Intrusive)
NOTE: This intrusive test will only be run if
the Small Leak (passive) test fails, or is
inconclusive (the switch does not close)
Enabling Conditions:
•
40 °F to 90 °F
• Engine temperature at startup within 10 °F of
the ambient temperature
• Fuel level less than 85%
The intrusive Medium and Large leak are con-
ducted as follows:
• De-energize the NVLD solenoid to seal the can-
ister vent.
•
Activate purge shortly after closed loop. Pull the
tank vacuum past the vacuum switch point (1
H2O vacuum) of the NVLD for a specific time
while tracking the standard purge flow rate.
• Turn purge off and determine how long it takes to
decay the tank vacuum and reopen the switch.
Determine the leak size from the time it took to
reopen the switch. Note: Fuel level is an impor-
tant determining factor.
•
If the switch does not close, a more aggressive
purge flow will be applied to determine if it is a
very large leak, missing fuel cap, problem with
the NVLD device, purge flow problem, etc...
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