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.
Automatic Trans: Diagnosis: Self-Diagnostics: Notes
PCM includes a self-diagnostic system. When a malfunction occurs, PCM will illuminate SERVICE ENGINE SOON and/or SHIFT TO D2 light located on instrument panel. When a problem is detected and light is turned on, a corresponding trouble code will be stored in PCM memory. Problems are recorded as hard failures or as intermittent failures.
PCM will also store other problems as information flags in malfunction history. Information flags will not turn on SERVICE ENGINE SOON or SHIFT TO D2 light. Information flags are used as a diagnostic tool to help technician when hard failures or intermittent failures occur.
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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.