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.
Idle Control System: Notes
Idle speed is controlled by ECU through AAC valve and Fast Idle Control Device (FICD) valve. ECU controls idle speed component(s) based upon signals received from various input devices. If idle speed component(s) test correctly but idle speed is not being regulated properly, check input signals to ECU. See IDLE SPEED SYSTEM INPUT SIGNALS table.
| Application | Model Usage | ||||||
|---|---|---|---|---|---|---|---|
| A/C Clutch Signal (1) | G20 & M30 | ||||||
| Battery Voltage | G20 & M30 | ||||||
| Crank Angle Sensor | G20 & M30 | ||||||
| Engine (Coolant) Temperature | G20 & M30 | ||||||
| Ignition (START) Switch | G20 & M30 | ||||||
| Neutral Switch | (2) G20 | ||||||
| Park/Neutral (Inhibitor) Switch | G20 & (3) M30 | ||||||
| Power Steering Pressure Switch | G20 & M30 | ||||||
| Throttle Position Sensor | G20 & M30 | ||||||
| Throttle (Idle) Switch | M30 | ||||||
| Vehicle Speed Sensor | G20 & M30 | ||||||
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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.