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 Power Control System
For "EPC", the throttle valve is not operated by a cable from the accelerator pedal. There is no mechanical connection between the accelerator pedal and the throttle valve.
The position of the accelerator pedal is communicated to Motronic Engine Control Module (ECM) J220 by Throttle Position (TP) Sensor G79/Accelerator Pedal Position Sensor 2 G185 (variable resistances; stored in one housing) that are connected with the accelerator pedal.
The accelerator pedal position (drivers intention) is a main input unit for the Motronic Engine Control Module (ECM) J220.
Operation of the throttle valve occurs by an electric motor in the Throttle Valve Control Module J338. This is true across the entire engine speed and engine load spectrum.
Throttle valve is operated by Accelerator Pedal Position Sensor 2 G185 according to specifications of Motronic Engine Control Module (ECM) J220.
With engine off and ignition switched on, Motronic Engine Control Module (ECM) J220 controls the Throttle Valve Control Module J338 exactly according to specifications of Throttle Position (TP) Sensor G79/Accelerator Pedal Position Sensor 2 G185. This means, if the accelerator pedal is depressed half way, the Accelerator Pedal Position Sensor 2 G185 opens the throttle valve to the same degree; i.e. throttle valve is then opened approx. half way.
With engine running (under load), Motronic Engine Control Module (ECM) J220 can open or close the throttle valve independently of Throttle Position (TP) Sensor G79/Accelerator Pedal Position Sensor 2 G185.
This means, for example, that the throttle valve could be fully opened even though the accelerator pedal has only been depressed half way. This has the advantage of preventing torque losses at the throttle valve.
In addition to this, it results in significantly better values relative to emissions and consumption under certain load conditions.
It would be incorrect to think that "EPC" consists of only one or two components. "EPC" is much more of a system containing all components that contribute to recognizing, controlling and monitoring the position of the throttle valve.
- Observe Safety Precautions.
- Observe Clean Working Conditions.
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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.