Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Electronic Spark Control System: Operation
The Spark Control Computer functions in 2 modes, "Start" and "Run". During engine cranking, "Start" mode is in operation. A fixed advance (basic timing) is used during this mode. After engine starts, "Run" mode takes over. (The 2 modes never operate at the same time). Now, amount of timing advance is controlled by computer, based upon information received from all engine sensors.
The pick-up coil signal is a reference signal. When received by computer, maximum amount of timing advance is made available. Computer determines how much advance is needed at that instant, based on data from sensors. If for some reason failure of the "Run" mode occurs, the "Start" mode will come back into service and allow vehicle to be driven. If failure of the computer occurs, system will go into "Limp-In" mode. This will allow vehicle to be driven until repairs can be made, however very poor performance and economy will result from either type of failure. If failure of pick-up coil or "Start" mode of computer occurs, engine will not start or run.
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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.
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