A signal generator is provided which produces a signal indicative of a throttle position of an engine on a vehicle. A plurality of split electrodes are formed on a printed electrical circuit substrate, and are connected with respective output leads. A less than 360.degree. rotating shaft which is connected with a rotatable shaft of a throttle valve has secured thereto an electrically conductive slider having a plurality of radially extending legs which fixedly carry contact members disposed for contact with the plurality of split electrodes. Each contact member corresponds to only one split electrode. A lead which is connected to one of the split electrodes assumes a ground potential or a constant positive potential. Consequently, the potential of the slider is maintained at such ground or constant positive potential, while the remaining split electrodes assume the ground or the constant positive potential only when they are engaged by contact members on the slider. In this manner, the output is in the form of a bi-level signal, and the combination of outputs from the plurality of leads constitute together a code. The pattern of the plurality of split electrodes which provides a coded output is configured such that a change in the potential occurs only in one bit of the code for each rotation of the rotating shaft through a given angle. Thus, a Gray code is formed for the angle of rotation of the rotating shaft.