Volvo B6324S Functional Description page 14

3. Small leak test phase
If the conditions for a small leak check (³0.02- inch)
are set the pump motor remains on in monitoring
mode until an elliptic combination of the relation
pump current and area ratio are fulfilled, or a maxi-
mum time limit has been reached. The judgment is
based on a test value which is a combination of the
actual area ratio and gradient of area ratio with respect
to relative pump current. If the estimated leak size is
close to the fault limit (0.020" leaks) the monitor may
decide to extend the run time of the pump to encrease
the build up pressure. This will make the judgement of
a small leak safer.
To carry out the leak diagnostic it is necessary that:
- Engine-on time is at least 20 minutes and last engine-
off time is more than 5 hours.
- ECM (=Engine Control Module) is in after run
mode
- Engine speed is 0 rpm
- Vehicle speed is 0 km/h
- Altitude is less than (or equal to) 2500 meters
- Engine coolant temperature is above (or equal to) +4°C
- Ambient temperature is between +4°C and +35°C
- Fuel level between 15% to 85% when no fuel level fault
- Fuel level is not used if fault on fuel level
- Rate of change of the initial relative pump current is
low enough
- Concentration of fuel vapor in the EVAP canister is
not excessive
- Battery voltage between 11.0 V and 14.5 V
- Purge valve is closed.
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If the test value is very near to set 0.02 inch leakage
the reference leak measurement phase is performed
again in order to compensate test value and make
a final judgment. If the motor current decreases or
increases too much during one of the tests, the test is
aborted and a new leak test will be performed in the
next after run.
Monitoring conditions
With the following errors the leakage detection moni-
toring can not be performed. These errors will there-
fore disable the leakage detection monitoring and the
MIL (and the corresponding fault code) will be set.
The disable conditions are:
- Error on power stages DM-TL pump
- Error on power stage purge valve
- Error on purge valve
- Error on change-over valve