Diagnosis & Repair (Using Toyota Scan Tester)

Inspect vacuum hoses. See appropriate illustration in VACUUM DIAGRAMS article. Repair as necessary. If all hoses are okay, inspect VSV. Using scan tester, select ACTIVE TEST mode. Check operation of VSV when activated by scan tester. VSV is mounted on top right rear of engine.
Start and run engine. With EGR system off, air from port "E" should exhaust from small filter on end of valve. See Fig 1. With EGR system on, air from port "E" should exhaust from port "F". If valve operates as specified, go to step 6). If valve does not operate as specified, go to next step.
Remove EGR VSV. Using ohmmeter, measure resistance between valve terminals. Resistance should be 37-44 ohms at 68°F (20°C). Check for continuity between each terminal and body of valve. If continuity exists, replace VSV. If continuity does not exist, go to next step.
Check VSV operation. Apply battery voltage to VSV terminals. Air should from port "E" should exhaust from port "F". See Fig 1. Remove battery voltage from valve terminals. Air from port "E" should exhaust from small filter on end of valve. Replace VSV as necessary. If VSV operates as specified, go to next step.
Check for and open or short circuit in wiring harness between instrument panel fuse block and ECM. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair as necessary.
Inspect EGR vacuum modulator. See SYSTEM/COMPONENT TESTS article. Replace as necessary. If modulator is okay, inspect EGR valve. See SYSTEM/COMPONENT TESTS article. Replace as necessary. If components are okay, go to next step.
Check Manifold Absolute Pressure (MAP) sensor. See SYSTEM/COMPONENT TESTS article. Replace MAP sensor as necessary. If MAP sensor is okay, replace ECM and retest.

Fig 1: Identifying EGR VSV