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Diagnostic Trouble Code (DTC) Detecting Criteria (H4DOTC) (Except Sti): Overview Subaru Impreza GH

Testing & Diagnostics 6 illustrations ~280 words

COMPONENT DESCRIPTION

Pressure control solenoid valve

PCV controls the fuel tank pressure to be equal to the atmospheric air pressure. Normally, the solenoid is set to OFF. The valve opens and closes mechanically in accordance with the pressure difference between tank and atmospheric air, or tank and canister.

The valve is forcibly opened by setting the solenoid to ON at the time of diagnosis.

Scheme 286

Scheme 286: COMPONENT DESCRIPTION

Valve Operation and Air Flow

In the figure below, divided by the diaphragm, the part above X is charged with atmospheric air pressure, and the part below X is charged with tank pressure. Also, the part above Y is charged with tank pressure, and the part below Y is charged with canister pressure.

If the atmospheric air pressure port is A, tank pressure port is B, and canister pressure port is C, the air flows according to pressure difference from each port as shown in the table below.

Scheme 287

Scheme 287
Condition of pressureFlow
A < B (solenoid OFF)B --> C
B < C (solenoid OFF)C --> B
Solenoid ONB <-- --> C

AIR FLOW REFERENCE CHART

When A < B (solenoid OFF)

Scheme 288

Scheme 288

When B < C (solenoid OFF)

Scheme 289

Scheme 289

When Solenoid is ON

Scheme 290

Scheme 290

Drain valve

Drain valve controls the ambient air to be introduced to the canister.

Scheme 291

Scheme 291

Vehicle speed signals are taken in to the ABS control module and hydraulic control unit, and normal/erroneous data of the ABS wheel speed sensor is received by CAN communication from the ABS control module and hydraulic control unit.

ECM and TCM are connected by high speed CAN.

(Common Specifications)

CAN Protocol 2.0 B (Active)

Frame Format: 11 Bit ID Frame (Standard Frame)

(High speed CAN)

Conforms to IS011898

Communication Speed: 500 kbps