INSPECT INTAKE MANIFOLD
Inspect the diaphragm.
Using a vacuum pump, apply a vacuum of 60 kPa (450 mmHg, 17.7 in.Hg) or higher to the diaphragm chamber. Wait for 1 minute and check that the needle of the vacuum pump does not lower.
If the result is not as specified, replace the intake manifold.
After applying vacuum in the step above, check that the actuator rod operates.
Check that the vacuum hose is not clogged.
If the result is not as specified, replace the vacuum hose.