V70 XC AWD L5-2.4L Turbo VIN 56 B5254T (1998)
Leak Detection Valve: Description and Operation
EVAP CANISTER SHUT-OFF VALVE
Certain markets require the engine control module (ECM) to detect leakages in the tank system, in these markets a leakage diagnostic has been
In order to check the fuel tank system, cars in these markets have an EVAP Canister Shut-off Valve (5). This is mounted in front of the left
A-pillar, inside the front fender and is connected to the EVAP canister opening. The valve is connected to a 12 V supply from the main relay
and can be grounded by the engine control module (ECM). The engine control module (ECM) can close the valve by grounding the cable. The
EVAP canister shut-off valve valve is normally open, it is only closed when the engine control module (ECM) is checking the system.
Normally the canister purge (CP) valve is closed and only opens when the engine control module (ECM) is emptying the canister. When the
EVAP canister is emptied the valve is first pulsed, this pulsing increases to bring the mixture from the canister up to a value which varies
according to engine load and speed. Because of the negative pressure in the inlet manifold, fresh air is sucked into the engine through the
EVAP canister opening or through the EVAP canister shut-off valve. As the air passes through the EVAP canister, fuel stored in the activated
charcoal is drawn into the engine and burned.