1972-74 All Models
- Ensure ambient temperature is greater than 65°F (18°C). Run engine at idle speed and alternately move throttle valve from idle to partial load positions. When doing this, an audible sound should be heard from the electromagnetic cut-off valve.
- Disconnect vacuum hose from EGR valve and plug hose. Apply vacuum to EGR valve. Engine should run rough or stall. If EGR valve functions as described, system is functioning properly.