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Each weekday Marshall Brain answers
questions submitted by the readers of How Stuff Works
in the Question of the Day section of HSW.
You can also view previously answered questions in
the HSW Question Archive.
Here is today's question!
Question
I have heard that all cars contain computers.
What does the computer in a car do? Will cars start on January 1, 2000?
Answer
All cars manufactured today contain at least one computer. It is in charge of monitoring engine emissions
and adjusting the engine to keep emissions as low as possible. The computer receives information from
a many different sensors, including:
- The oxygen sensor
- The air pressure sensor
- The air temperature sensor
- The engine temperature sensor
- The throttle position sensor
- The knock sensor
- The oxygen sensor
Using the information from these sensors, the computer can control things like the fuel injectors, spark
plugs and the idle speed to get the best performance possible from the engine while keeping emissions low.
The computer can also sense when something has gone wrong and can inform the driver with the "Check Engine"
light. A mechanic can read a diagnostic code from the computer and fix the problem.
Depending on how expensive the car is, there can be all sorts of other computers. For example:
- There is probably a computer controlling the automatic transmission
- If the car has anti-lock brakes, there is a computer reading the wheel speed and controlling the brakes
- Many air bag systems have their own computers
- A car with keyless entry or a security system has a computer for these systems
- Advanced climate control systems often have computers
- Some cars now have motorized seats and mirrors that can remember the settings for multiple drivers, and these contain computers
- Any radio or CD player with a digital display contains a computer of its own
- Cruise control systems use computers
In other words, a modern luxury car is a rolling computer network!
It is amazing how many embedded controllers a car can have!
So what will happen to our cars on January 1, 2000? Nothing. The computers in our cars have
no idea what today's date is because it is irrelevant to their calculations. If
you take the battery out of your car to replace it, all of the computers lose power. Your radio, for
example, may forget its preset stations. However,
you don't have to reset the date on any of these embedded computers because none of them care.
Therefore there is nothing to worry about on January 1 - cars will run fine.
Interesting links:
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