Circuit allowing the transfer of all the status information needed in a car or truck over a single low-cost wire pair, minimizing electrical wire usage. It can be used to interconnect powerful functions and to control and interface car body electronics. Virtually any microprocessor, including those with SPI/SCI interfaces, can be connected with ease.This circuit is fully compliant with ISO standard 11519-3, supporting a wide range of applications such as low-cost remote control switches typically used for lamp control and complex, highly-autonomous, distributed systems like engine controls.It is a microprocessor-interfaced line controller for mid-to-high complexity bus-masters and listeners like injection/ignition control calculators, dashboard controllers, and car stereo or mobile telephone CPUs.