Fig. 1: A manifold vacuum gauge can be used to check
a variety of vacuum-controlled components
Disconnect the electrical connectors from the thermo switch. Connect a jumper
wire between the connectors to simulate a complete circuit.
Turn the ignition switch ON.
Disconnect the vacuum hose from the EGR valve and blow into the hose. Air
should be discharged from the three-way solenoid valve relief port. If it
is not, replace the three-way valve.
Turn the ignition switch off, and remove the jumper wire from the thermo
switch connectors. Disconnect the vacuum amplifier vacuum line from the three-way
solenoid. Turn the ignition switch back to ON.
Blow into the vacuum line disconnected from the EGR valve, and check for
air discharge from the vacuum amplifier port on the three-way solenoid valve.
If there is no discharge, replace the solenoid valve.
After completion of all tests, reconnect the hoses to their original locations.
