The Computer in the Car: First Used in 1975 Chevrolet Cosworth Vega
Computers in cars are so common today, many do not recall that before 1975, none of them had them to regulate engine functions etc. Today, they control everything making it hard to repair and troubleshoot for do-it-yourselfers.
The first car to really have an onboard computer was the 1975 Chevy Cosworth Vega, sub compact, which really was an analog computer in a box behind the dash. It was called the ECU, or electronic control unit and made up of hundreds of diodes etc. It would analyze all combination of input to meet the needs of of its twin over-head cam, four cylinder engine. With out the ECU, like today's cars, it really could not run well, if at all, due to its electronic fuel injection system, another first for American cars.
The ECU was pre-programmed to monitor the car's engine and spray fuel into the engine cylinders. All sensor impulses were received and acted to determine the fuel requirements. The analog computer received information from 10 sensors.
The ECU was subject to damage if the battery ground cannot be disconnected. The black connector of the ECU had to be the first to be disconnected and the last one connected. If you did not do this, the analog computer would be shorted out and had to be replaced!