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.
1987 Chevrolet Chevette L4-98 1.6LFACTORY OEM SERVICE PROCEDURE
Computer Command Control (C-3) System
The ECM is the control center of the C-3 system. Its function is to monitor input information from the various sensors, process this information, then generate output commands to the various systems that affect the performance of the vehicle.
The ability of the ECM to perform these functions is dependent upon a removable calibration unit called the PROM. There are specific ECM/PROM combinations for each vehicle and they should not be interchanged.
The ECM also performs the diagnostic function of the C-3 system, alerting the driver through a ``Check Engine'' light should any problem in the system arise and storing a code or series of codes which the technician uses as an aid in making repairs.
Factory Service Tools
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
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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.