The term “car brain box” might sound like something out of science fiction, but it’s essentially the nickname for the computer that controls various functions in your vehicle. In modern cars, this is known as the ECU (Engine Control Unit) or ECM (Engine Control Module), a sophisticated piece of technology that requires complex programming. But what did a “car brain box” look like in the early days of automotive technology? Let’s take a fascinating look inside a 1968 Automatic Temperature Control (ATC) “brain” to understand the roots of car computer systems.
Delving Inside the 1968 ATC “Brain”: An Early Automotive Control System
While not a programmable engine management system in the way we understand it today, the 1968 ATC unit served as a crucial “brain” for managing the climate control in luxury vehicles like Lincolns. This electromechanical marvel offers a glimpse into the ingenuity of early automotive electronics.
Vacuum Control System
One of the first things you notice when examining the 1968 ATC brain box is the heavy reliance on vacuum. Unlike today’s electronic sensors and actuators, this system utilized vacuum lines and solenoids to control various functions.
The image above shows the components related to fan speed and direction, which were controlled by vacuum. These vacuum lines were integral to directing airflow and managing different climate control modes within the vehicle.
Solenoids and Diverter Doors
The system employed vacuum solenoids to manage the diverter doors inside the car’s dashboard. These solenoids acted as electrically controlled valves, directing vacuum to actuators that moved the doors.
As seen above, these solenoids were responsible for crucial functions like switching between heat and defrost, or heat and air conditioning. They also managed the heater valve, controlling the flow of coolant to regulate heat output. The temperature itself was managed by blending hot air with fresh air, a relatively sophisticated approach for its time. A vacuum transducer, a brass component, played a role in converting vacuum signals to electrical signals or vice versa, bridging the vacuum and electrical systems.
Relays and Fan Speed
Relays were another key component within this early “brain box.” These electromechanical switches were crucial for controlling higher current devices like the fan motor and managing fan speed.
The relays, with their hand-wired connections, allowed the system to switch between different fan speeds using resistors. These Bendix relays, as shown in another image, are a testament to the technology of the era, and finding replacements today can be challenging.
Temperature Comparator Circuit Board
At the heart of the automatic temperature control was a circuit board designed to compare temperature readings and adjust the system accordingly.
While seemingly basic by today’s standards, this temperature comparator circuit board represented an early form of electronic control in automobiles. It could be reverse-engineered by an electrical engineering student, highlighting the accessible nature of the technology compared to modern, highly integrated systems.
Wiring Complexity
Looking at the underside of the circuit board reveals a complex web of wires. Each wire served a specific purpose, connecting to different components to manage speeds, diverter selections, and various combinations of climate control functions.
The sheer number of wires underscores the complexity involved in achieving “automatic” climate control in 1968. The solenoids, though appearing simple, were intricately connected to create a functional system.
Manual vs. Automatic “Brain Boxes”: A Simpler Approach
For vehicles without automatic climate control, a manual system was employed. Interestingly, even these manual systems had a “brain box,” albeit a much simpler one.
Manual Heater Control Box
The manual heater control box lacked the electronic circuit board of the ATC system. Instead, it relied purely on vacuum solenoids directly controlled by the dashboard controls.
Solenoids in Manual Systems
In the manual system, four solenoids typically managed the heater valve, heat/AC diverter, heat/defrost diverter, and recirculation actuator. These were activated directly by the buttons and levers on the dashboard.
Simplicity and Reliability
The manual system’s simplicity made it inherently more reliable. With no electronics to fail (beyond basic solenoids and wiring), issues were typically limited to vacuum leaks or mechanical problems with the control head. Temperature control was achieved through a simple blend door, adjusted by a vacuum valve on the dashboard.
Conclusion: From Electromechanical Brains to Modern Programming
Exploring the 1968 ATC “brain box” provides a valuable perspective on the evolution of automotive control systems. While we now think of “programming car brain boxes” in terms of software and code for ECUs, these early systems were programmed through clever electromechanical design and vacuum logic. They represent a significant step in automotive technology, paving the way for the sophisticated electronic control units that manage nearly every aspect of modern vehicles, from engine performance to advanced driver-assistance systems. Understanding these historical systems helps appreciate the incredible journey of automotive technology and the increasing complexity hidden beneath the hoods of our cars today.
