EGR Modulator
- Remove vacuum hoses from modulator. Plug modulator ports No. 2 and No. 3. See Fig 1 . Connect hand-held vacuum pump to port No. 4 and apply vacuum. Vacuum should not hold. If vacuum holds, check for plugged modulator filter. If filter is not plugged, replace EGR modulator.
- Connect vacuum hose to modulator port No. 5. Blow into hose. Again apply vacuum to port No. 4. Vacuum should now hold. If vacuum does not hold, replace EGR modulator.