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Tech Sense by John Bell June 2022: Computers and Cars



I have been writing this column for several years now and it is hard for me to believe that I have never written about computers and cars. Especially since I spent several years flying to Detroit every week to support projects at various auto manufacturers. While Electronic Control Units (ECU’s) have been around since 1968, in 1976 GM announced a partnership with Motorola and a plan to eventually include a microcomputer in every car they built. This microcomputer was the 6802, and by 1981 GM had achieved their goal. By the way the 6802 just happened to be the same microcomputer that I used to design and build my first computer as my senior project at University of Maryland. A car built today typically has hundreds of microprocessors.


Before Computers

Before computers were put into cars, everything was done mechanically. A modern car of the 1960’s and 70’s would typically control the air and fuel mix using a carburetor with a valve and throttle. A distributor controlled the timing of the spark from the spark plugs by spinning contacts across the points. Your foot provided pressure to hydraulic brakes and a cable was often used to tighten the emergency brakes.

This mechanical system worked and in general worked well, so why the move to electronics? It seems there were several forces at work; a desire to reduce air pollution caused by cars, a desire to improve fuel efficiency, and a desire to improve car safety.


1. That was Then, This is Now

Today, a computer system controls the spark, the amount of fuel injected into the cylinder, and the air intake to optimize performance, minimizing fuel consumption, and creation of pollutants. Another computer system controls the brakes adding features like anti-lock braking (no more manually pumping brakes on slippery roads) and traction control to reduce the slipping and sliding on wet roads. We also have safety airbags that can respond in milliseconds when a crash is detected to protect the car’s occupants.


2. Vehicle Diagnostics and OBD II

The U.S. Government wanted a way to easily test cars to determine if all of the pollution equipment was working. With the computer-controlled automation being added to the cars the government pointed out to auto manufacturers that NASA was using microcomputers to diagnose and sometimes even repair satellites while in space and pointed out that the diagnostics could be done for cars. This would allow periodic inexpensive testing to make certain the pollution controls were working. They also worked with the industry to create a standard connector, buss, and set of messages that could be used to connect to the vehicle and read information from it. The current version of this is called OBD II (On Board Diagnostics). This has been standard on US cars since 1996.

If a problem is detected on the car it puts up a signal which causes the check engine light to illuminate. An OBD II scanner can be attached to the OBD II connector (normally found under the dash near the steering wheel) and the error code can be read. The error code can then be looked up online to find the likely cause of the problem.

There are many scanners available for purchase. I typically use a scanner that connects to a phone or computer using Bluetooth. These are available through sites like Amazon for under $20. Many parts stores like auto Zone and Advanced Auto Parts (both in Beltsville) will also read the OBD II bus for you for free. A dealership service department will often bill more than $100 to read the diagnostic.

A car has a lot of data it collects to send to the computers. This data comes from sensors. For example, there is a temperature sensor in the oil that measures the oil temperature. It may show this on the dash in degrees or the dash may simply show a red-hot light if the oil gets too hot. Simple lights that don’t show a measurement but just an indicator are called idiot lights. The same for water temperature for the coolant system. An ODB scanner often allows reading of the actual values coming from the sensors even if the dash only has idiot lights.


3. Additional Features through Software

If a system on a car is computer enabled, it is often possible to add features without the need to add additional hardware. For example, if you have electronic door locks, it is often possible to program the door to unlock automatically when the engine is turned off and lock again. Some makes of cars will even enable features to their car for a fee. On some cars, BMW will enable a heated wheel feature for an annual fee. I don’t consider this a good thing, essentially, they want you to pay for using something that is already built into the vehicle.


4. Firmware Updates and Changes

Computers also means software or in this case firmware. It is the firmware that makes the computers so flexible, instead of changing the computer, the firmware can be changed to give the computer new instructions either fixing things that were broken or giving the car new capabilities. If something is broken due to a programming error it can be fixed by installing an update. Some cars will allow you to do this over Wi-Fi, but most require the car to be serviced by a dealer.

Several States are passing laws that mandate that car companies make the tools and code required to repair cars with built-in computers to be made available so that non-dealer repair shops and do-it-yourselfers can update, modify, and repair the code in the cars computers. This is known as “the right to repair” and impacts tractors, bulldozers, and other large machinery. There have also been discussions about creating a federal law protecting consumers but being locked out of choosing who can work on their car.


5. Car Hacking

Of course, in this day and age, anytime there is a computer there is the possibility of hacking it. Today the most common hack is the remote unlocking of the car doors without physical access to the keys. Most of the others seen on TV shows and movies where someone takes control of your car and steers it into something, accelerate, or slam on the brakes, are just story telling. At least for normal unmodified cars that most of us drive.


Wrap Up

I hope you enjoyed out short discussion of about computers and cars. When you reach out to your favorite politician don’t forget to request the right to repair. And while you are visiting the car dealership ask why it may cost up to $400 to get a duplicate key that should only cost about $50. But that’s another story.

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