P0402

SYSTEM DESCRIPTION
The EGRC-BPT valve monitors exhaust pressure to activate the diaphragm, controlling throttle body vacuum applied to the EGR valve. In other words, recirculated exhaust gas is controlled in response to positioning of the EGR valve or to engine operation.




DIAGNOSTIC TROUBLE CODE CONFIRMATION PROCEDURE

ON-BOARD DIAGNOSIS LOGIC
If too much EGR flow exists due to an EGRC-BPT valve malfunction, off idle engine roughness will increase. If the roughness is excessive, then the vacuum to the EGR valve is interrupted through the EGRC-solenoid valve. If the engine roughness is reduced at that time, the EGRC-BPT valve malfunction is indicated.




OVERALL FUNCTION CHECK
Use this procedure to check the overall function of the EGRC-BPT valve. During the check, a DTC might not be confirmed.
1) Disconnect the rubber tube to the fuel pressure regulator from the intake manifold at the fuel pressure regulator.
2) Disconnect the rubber tube to the EGRC-solenoid valve from the EGRC-BPT valve at the EGRC-solenoid valve.
3) Connect these two rubber tubes using a rubber tube that is approx. 2 meter in length and has 1 mm (0.04 in) dia. orifice made in it. (The intake manifold vacuum will be directly applied to the EGRC-BPT valve.)
4) Start engine.




5) Check for the EGR valve lifting with engine at less than 1,500 rpm under no load.

EGR valve should remain closed or slightly lift up.

6) Keep engine speed at about 2,000 rpm, then check the EGR valve lifting when revving engine up to 4,000 rpm under no load.

EGR valve should lift up to the full position, and go down without sticking when the engine is returned to idle.

7) Check rubber tube between the EGRC-solenoid valve and throttle body for improper connections, cracks or obstruction.

COMPONENT INSPECTION




1. Plug one of two ports of EGRC-BPT valve.
2. Vacuum from the other port and check leakage without applying any pressure from under EGRC-BPT valve.

Leakage should exist.