Serial Data Communications

Government regulations require that all vehicle manufacturers establish a common communication system. This vehicle utilizes a "CLASS 2" communication system. Each bit of information can have one of two lengths: long or short. This allows vehicle wiring to be reduced by transmitting and receiving multiple signals over a single wire. Messages carried on Class 2 data streams are also prioritized. If two messages attempt to establish communications on the data line at the same time, only the message with higher priority will continue. The device with the lower priority message must wait. The most significant result of this regulation is that it provides scan tool manufacturers with the capability to access data from any make or model vehicle that is sold. Data displayed on other scan tools will appear with some exceptions, the same. Some scan tools will only be able to display certain vehicle parameters as values that are a coded representation of the true or actual value. On this vehicle the scan tool displays actual values for vehicle parameters. It will not be necessary to perform any conversions from coded values to actual values.