Diagnostic System

1984 Toyota Celica GT, 2D Hatchback, AutomaticSECTION Diagnostic System

The ECU of the ECS is equipped with a self-diagnostic system which detects system failures or abnormalities. When a malfunction occurs, the ECU lights the "CHECK ENGINE" lamp located on instrument panel. At the same time, a corresponding trouble code is stored in ECU memory. Interpretation of the trouble codes can be performed by observing number of flashes of "CHECK ENGINE" lamp.

All codes are stored in memory from the time of detection until the codes are cleared from the memory. The "CHECK ENGINE" lamp will go out as soon as the malfunction is cleared; but the code will remain in memory.

As a bulb and system check, the "CHECK ENGINE" lamp will glow when ignition switch is turned on and engine is not running. When engine is started, the lamp should go out after a short period of time. If not, a malfunction has been detected in the ECS.

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When to See a Mechanic

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

  • β€’ You smell fuel, burning insulation, or see smoke.
  • β€’ Brakes feel soft, pull hard to one side, or make grinding noises.
  • β€’ The engine overheats, stalls repeatedly, or misfires under load.
  • β€’ You are missing required tools, torque specs, or safe lifting equipment.
  • β€’ You are not confident in the next step or safety outcome.