by Walt Sampson
Palms automobile engine image from Fotolia.com
The Vacuum Switching Valve (VSV) is part of the 1998 Toyota Camry Exhaust Gas Recirculation (EGR) system. The VSV is connected to the EGR valve. The function of the EGR system is to recirculate the exhaust gases to the engine intake manifold and thus reduce the nitrous oxide emissions of the vehicle (References 1). Detecting a faulty VSV is difficult, but can be accomplished after completing a few tests.
Locate the vacuum switching valve. It has three vacuum hoses and a two-wire electrical connector attached to it. On four-cylinder engines, the VSV is located at the rear of the engine below the intake manifold. On six cylinder engines, the VSV is located under the V-Bank cover (a finned plate), which must be unscrewed with an Allen wrench and then removed by lifting it off its retaining clips. The VSV is next to the intake manifold.
Check resistance. Remove the electrical connector from the VSV and check the resistance across the terminals with an ohmmeter. Resistance should be 33 to 39 ohms (at 68 degree air temperature). Resistance outside of this range indicates that the VSV is bad (References 1).
Continuity test. Verify, using the ohmmeter, that there is no continuity between any of the VSV terminals and an electrical ground on the motor. Any continuity in either terminal indicates that the VSV is bad.
Hit test. Remove the vacuum hoses from ports E and G. Blow air into port E and check that it comes out of port G. If not, the VSV is damaged.
Apply voltage and blow air. Apply battery voltage across the VSV terminals using wires from the battery terminals. Blow air into port E and see if it comes out of port F. If not, the VSV is bad (References 1).
Articles will need
- Allen wrench
- Cables (with clips to connect to battery terminals and VSV terminals)
- Vacuum hose (to connect to port E and blow through VSV)