Brian Benchoff is working to restore a vintage electric car (a 1980 Comuta-Car). A car that old predates current vehicles which use CAN bus to talk to various parts. And buying any new automotive parts will come with those parts using CAN.
My restoration of a a vintage electric car includes significant upgrades. Because the motor was beyond repair, I upgraded to a more powerful AC induction motor. This required a modern motor controller, and because hybrid and electric vehicles are hitting the scrap heap, I decided to move away from heavy lead acid batteries to modern lithium packs. All of these upgrades mean the stock dashboard electronics are obsolete; the stock speedometer is run off a cable, and the new motor does not have a cable connected to the shaft. Any sort of voltage measurement on the stock dashboard would be wildly inaccurate with the different cell chemistry and higher voltage.
In short, to upgrade this car to modern electronics, the easiest path forward is to replace all of the electronics.
With CAN bus, instead of using control relays, each of the lights on the exterior of the car – turn signals, marker lights, brake lights – are each connected to their own MOSFET. There are optoisolators to read the state of switches, a display for the speedometer and a CAN-enabled Reverse-Neutral-Drive switch.
Read more in the post here.