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 System: Description
Mercedes-Benz 380 and 500 series vehicles are equipped with an electronic idle speed control which maintains a constant idle speed under all engine operating conditions. A pre-set fast idle is controlled when the engine oil temperature is cold. When the engine oil temperature reaches 60°F (16°C), idle speed is lowered and held steady even when engine loads vary.
The system includes the idle speed adjuster, idle air distributor, idle speed control unit, temperature control switch and connecting hoses.
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.