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 Control Module (ECM)
The ECM maintains proper spark and fuel injection timing for all driving conditions. The ECM monitors input signals from the following components to control Electronic Spark Timing (EST):
- C(3)I Ignition Module
- Coolant Temperature Sensor (CTS)
- Manifold Air Temperature (MAT) Sensor
- Mass Airflow Sensor
- Park/Neutral Switch
- ESC Module
- Throttle Position Sensor (TPS)
- Vehicle Speed Sensor (VSS)
Under 400 RPM, the ECM will start injector timing as soon as the C(3)I ignition module receives a cam signal, synchronizes spark timing, and controls fuel injection timing.
The C(3)I ignition module controls spark timing during this period. Over 400 RPM, the ECM controls EST and on 3.8L engines, it also changes fuel injection timing to a sequential mode (provided a camshaft signal is received).
NO RELATED
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
Affiliate disclosure: We may earn a commission at no extra cost to you.
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.