EGR Modulator

Remove vacuum hoses from modulator. Plug modulator ports No. 2 and No. 3. See Fig 1 . Blow into port No. 4. Air should pass from filter.
Connect hand-held vacuum pump to port No. 5 and plug ports No. 2 and No. 3. Blow air into port No. 4. Vacuum pump should not obtain vacuum. Replace EGR modulator if defective.

Fig 1: Identifying EGR Modulator Ports

Courtesy of GENERAL MOTORS CORP.

EGR VACUUM SWITCHING VALVE LOCATION

Application

Location

Prizm

⁽¹⁾ Center Of Firewall

Prizm GSi

⁽²⁾ Rear Of Engine, Near Mass Airflow Sensor

⁽¹⁾	Connector contains Black/Red and Black/Yellow wires.

⁽²⁾	Connector contains Black/Red and Green/Red wires.

Fig 2: Identifying EGR VSV Ports

Courtesy of GENERAL MOTORS CORP.