Connect vacuum gauge to distributor sub-diaphragm hose. Check that coolant temperature is below 122°F (50°C). Start engine. Vacuum gauge should indicate high vacuum when engine is accelerated or running at idle. If not, check BVSV or check valve.
Warm up engine to normal operating temperature. Check that vacuum gauge indicates low vacuum at idle and high vacuum when engine is accelerated. If not, check BVSV. Remove vacuum gauge and reconnect hose.
Connect vacuum gauge to distributor main advance diaphragm hose. Set parking brake. Vacuum gauge should indicate high vacuum when power steering is operated, shift lever is shifted to "D" or engine is accelerated. If not, check VCV. Remove gauge and reconnect hose.
Remove distributor cap and rotor. Apply vacuum to diaphragms checking that vacuum advancer moves in accordance with vacuum application. If not, repair or replace vacuum advancer. Reinstall rotor and cap. Testing is complete.

Fig 1: Cressida Spark Control System

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

• You smell fuel, burning insulation, or see smoke.

• Brakes feel soft, pull hard to one side, or make grinding noises.

• The engine overheats, stalls repeatedly, or misfires under load.

• You are missing required tools, torque specs, or safe lifting equipment.

• You are not confident in the next step or safety outcome.

Safety Warning

System Testing: Cressida