NOTE: You will need a source of vacuum such as a vacuum pump
and a vacuum gauge to make these tests. You may be able to disconnect and plug
off the hoses leading to this valve, then operate the engine and use engine
vacuum to make the tests. In this case, you can tee a vacuum gauge into the
line which will apply vacuum.
- Note the routing of all hoses leading to the modulator valve, especially
the hose which is connected to the exhaust side of the EGR valve. Remove the
EGR Modulator valve. Plug the No. 1 port, then attach a source of vacuum to
the No. 3 port.
- Attach a clean hose to the exhaust gas port. Blow into the end of the hose
and maintain pressure. Apply vacuum to the No. 3 port, then seal off the source
of vacuum. Vacuum should be maintained as long as air pressure is applied.
- Stop applying air pressure. The vacuum should be released. If the valve
fails to respond properly in either Step 2 or 3, replace it.
- Note the routing of all hoses leading to the modulator valve, especially
the hose which is connected to the exhaust side of the EGR valve. Remove the
valve. Plug the ports numbered 2 and 3. Attach
a source of vacuum to the No. 1 port.
- Attach a clean hose to the exhaust gas port. Blow into the end of the hose
and maintain pressure. Apply vacuum to the No. 1 port, then seal off the source
of vacuum. Vacuum should be maintained as long as air pressure is applied.
- Stop applying air pressure. The vacuum should be released. If the valve
fails to respond properly in either Step 2 or 3, replace it.
