System Testing

1984 Toyota Celica GT, 2D Hatchback, AutomaticSECTION System Testing
  1. With engine cold, connect a vacuum gauge to distributor main advance diaphragm hose. Check that coolant temperature is below 86°F (30°C). Start engine. Vacuum gauge should indicate zero regardless of whether throttle valve is open or closed.
  2. Warm up engine to normal operating temperature. Check that vacuum gauge changes quickly when throttle valve is opened and closed. Stop engine. Remove vacuum gauge and reconnect hose to distributor.
  3. Remove distributor cap and rotor. Apply vacuum to diaphragms checking that vacuum advancer moves in accordance with vacuum. Reinstall rotor and cap. If system performed as described, testing is complete. If not, check individual components as necessary.
Fig 1: Spark Control System (Celica & Pickup)
G41578Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
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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.