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 Speed Control (ISC)
The ISC is an electrically driven actuator which changes throttle valve angle (in idle position), according to commands from ECM. The ISC maintains low idle speeds while preventing stalls due to engine load changes.
The ECM monitors engine load to determine proper idle speed. To prevent stalling, the ECM monitors A/C "ON" switch, Park-Neutral switch and ISC throttle switch. With this information, the ECM will control idle speed by operating the ISC motor.
When engine is cold, ECM holds throttle valve open for longer period of time to provide faster warm-up. This function is by-passed when throttle is opened enough to bring TPS off its idle circuit. The ISC is located on side of carburetor.
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.
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