The ME range of ECUs features multiple spare digital inputs. 


These inputs allow frequency signals (such as a Vehicle Speed Sensor, a Flex Fuel sensor or a Hall Effect Cam position sensor), or a switch type input. Simply wire the switch such that it connects the digital input to ground when triggered. 


The ME442 Wire In and ME221/ME442 Plug-Ins digital inputs all have an internal 1Kohm pull-up to 5 Volts. (meaning you only need to connect them to ground to "trigger" them)


You can map the physical pin to the chosen function from the "Input Settings" which is under the System node on the entity tree.