Troubleshooting Accelerator pedal sensor (pedal value sensor)

In modern vehicles, the share of electronic components is increasing all the time. Reasons include legal regulations e.g. in the field of emission and fuel consumption reduction. Electronic components are also taking over more and more functions which increase active and passive safety as well as driving comfort. One of the most important components is the accelerator pedal sensor.

Design
Non-contact sensors based on an inductive principle are being used more and more often for automotive applications. These sensors comprise a stator, which surrounds an exciting coil, receiver coils and an electronic unit for evaluation (see illustration), and a rotor which is formed from one or more closed conductor loops with a certain geometry.

Effects of failure

The following fault symptoms can occur if the accelerator pedal sensor fails: 
■ Engine only shows increased idling 
■ Vehicle does not react to accelerator pedal movements 
■ Vehicle switches to "limp-home" mode 
■ Engine warning light comes on 

There can be various reasons for failure: 
■ Damaged cables or connections at the accelerator pedal sensor 
■ Lack of voltage and ground supply 
■ Faulty evaluation electronics in the sensor

Troubleshooting

The following test steps should be taken into account during troubleshooting: 
■ Read out fault code 
■ Visual inspection of the accelerator pedal sensor for mechanical damage 
■ Visual inspection of the relevant electrical connections and cables for correct fit and potential damage 
■ Testing of the sensor with the aid of oscilloscope and multimeter.

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