EGR Modulator (Prizm)
- Remove vacuum hoses from modulator. Place finger over modulator ports No. 2 and No. 3. See Fig 1 . Blow into port No. 4. Ensure air passes through filter part of modulator.
- Connect vacuum pump to modulator port No. 5 and plug ports No. 2 and No. 3. While blowing into port No. 4, vacuum should bleed off at port No. 5. Replace modulator if not to specification.