RAM 3500 Chassis Cab Truck 2WD L6-6.7L DSL Turbo (2010)
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After the vehicle is started, the engine coolant temperature must be within 50°F (10°C) of ambient to indicate a cold start.
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The fuel level must be between 12% and 88%.
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The engine must be in closed loop.
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Manifold vacuum must be greater than a minimum specified value.
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Ambient temperature must be between 39°F and 98°F (4°C and 37°C) and the elevation level must be below 8500 feet (2591 meters).
The test is accomplished by the PCM activating the purge solenoid to create a vacuum in the evaporative system. The PCM then measures the amount of
time it takes for the vacuum to dissipate. This is known as the vacuum decay method. If the switch opens quickly a large leak is recorded. If the switch
opens after a predetermined amount of time, then the small leak matures. If the switch does not close, then a general evaporative failure is recorded. The
purge monitor tests the integrity of the hose attached between the purge valve and throttle body/intake. The purge monitor is a two stage test and it runs
only after the evaporative system passes the small leak test.
Even when all of the thresholds are met, a small leak won't be recorded until after the medium/large leak monitor has been run. This is accomplished by
the PCM activating the purge solenoid to create a vacuum in the evaporative system. The PCM then measures the amount of time it takes for the vacuum
to dissipate. This is known as the vacuum decay method. If the switch opens quickly a large leak is recorded. If the switch opens after a predetermined
amount of time, then the small leak matures. If the medium/large leak test runs and the ESIM switch doesn't close, a general evaporative test is run. The
purge solenoid is activated for approximately 10 seconds, increasing the amount of vacuum in the system. If the ESIM switch closes after the extended
purge activation, a large leak fault is generated. If the switch doesn't close, a general evaporative system fault is generated.
The purge monitor tests the integrity of the hose attached between the purge valve and throttle body/intake. The purge monitor is a two stage test and it
runs only after the evaporative system passes the small leak test.
Stage one of the purge monitor is non-intrusive. The PCM monitors the purge vapor ratio. If the ratio is above a calibrated specification, the monitor
passes. Stage two is an intrusive test and it runs only if stage one fails. During the stage two test, the PCM commands the purge solenoid to flow at a
specified rate to force the purge vapor ratio to update. The vapor ratio is compared to a calibrated specification and if it is less than specified, a one-trip
failure is recorded.
The ESIM switch stuck closed monitor checks to see if the switch is stuck closed. This is a power down test that runs at key-off; when the PCM sees 0
rpm's, the purge solenoid is energized for a maximum of 30 seconds, venting any vacuum trapped in the evaporative system. If the switch opens or was
open before the test began, the monitor passes. If the switch doesn't open, the monitor fails. This is a two-trip MIL. The star scan tool can be used to
force the ESIM switch stick closed monitor to run.
The PCM also uses the ESIM to detect a loose or missing gas cap. The PCM controller looks for a change in the fuel level (25% minimum) and then gas
cap is loose or missing. If a medium/large leak is detected, a loose gas cap light illuminates and a pending one-trip fault code is set. On the PCM, this is a
three-trip fault before the code matures
