How the accelerator pedal sensor works
Here you will find useful basic information and important tips relating to the accelerator pedal sensor/pedal value transmitter in vehicles.
Important safety note
The following technical information and practical tips have been compiled by HELLA in order to provide professional support to vehicle workshops in their day-to-day work. The information provided on this website is intended for suitably qualified personnel only.
Modern vehicles are being equipped with an ever-increasing number of electronic components. Among other things, this is due to legal regulations, e.g. those governing a reduction in emissions and fuel consumption. Electronic components are also increasingly being used to increase active and passive safety as well as driving comfort. One of the most important components is the accelerator pedal sensor.
When it comes to automotive applications, a non-contact sensor based on an inductive principle is increasingly being used. This sensor comprises a stator (which includes an excitation coil, receiver coils, and an electronic evaluation unit) and a rotor (formed of one or more closed conductive loops with a certain geometry).
The application of alternating voltage to the transmission coil produces a magnetic field which induces voltages in the receiver coils. A current is also induced in the rotor conductive loops which, in turn, influences the magnetic field of the receiver coils. Voltage amplitudes are produced depending on the position of the rotor relative to the receiver coils in the stator. These are processed in an electronic evaluation unit and then transmitted to the control unit in the form of direct-current voltage. This evaluates the signal and forwards on the relevant pulse, e.g. to the throttle valve actuator. The characteristics of the voltage signal depend on how the accelerator pedal has been pressed.
Accelerator pedal sensor (pedal value transmitter)
If the accelerator pedal sensor fails, the following fault symptoms may occur:
A failure could have a number of different causes:
The following test steps should be considered during troubleshooting:
Using the example of a MB A-Class (150) 1.7, the following test steps, technical data, and figures are listed to explain the troubleshooting work.
Control unit pin | Signal | Test conditions | Reference value |
---|---|---|---|
C5 blue-yellow | → | Acceleration off | 0V |
C5 | → | Acceleration off | 4.5 – 5.5 V |
C8 violet-yellow | ⊥ | Acceleration on | 0V |
C blue-grey | ← | Acceleration on, accelerator pedal released | 0.15V |
C9 | ← | Acceleration on, accelerator pedal pressed | 2.3V |
C10 violet-green | ← | Acceleration on, accelerator pedal released | C10 |
← | Acceleration on, accelerator pedal pressed | 4.66V | |
C23 brown-white | ⊥ | Acceleration on | 0V |
→ output signal ← input signal ⊥ control unit ground
The measurements should be performed by two people. The work involved in capturing the signals on the sensor, carrying out various test cycles, and performing diagnostics work on the oscilloscope is difficult for a single person to handle, and it will take them much longer to complete this work.
In this video, we will show you the technologies of the accelerator pedals, how they work and discuss the faults. In addition, we will show the diagnosis of the element? using mega macs and tell you what to look for.
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