Cars, Computers, and the American Way

Factual Questions
1

So I have a “check engine” light blinking on my dashboard. I know that my coolant is too thick, and the humidity is the culprit. Nothing to worry about in the heat, so I let it pass. How do I know? Some grease monkey told me. Also told me to get it up to 70 mph on the highway, and it’d probably blink out - sure enough. As soon as I hit 71 mph, the light went off.

A couple years ago, the “check engine” light went on, I went to the dealer, they said it was nothing - computer error.

Many years ago, I had my timing belt blow out. That’s a bitch to get fixed. $25 part, $8 gazillion in labor. Turns out, if I had gone in right before the belt blew, I’d have saved several hundred dollars in labor.

Which brings me to my point. With all the gizmos and technology out there, why in the world can I not get sensors and such galore packed onto my Taurus to tell me exactly what is wrong with my car, at any given moment? Why do I have to take it in to the dealer so some kid can hook it up to a computer he barely knows how to use to tell him?

It can’t possibly be cost-preventative, can it? A 64-bit processor costs pennies to make nowadays. Cell phones have more technology and infrastructure dedicated to them, and they’re less than a Benjamin ($100 to you squares out there).

What’s the deal?

2

you can get a simple computer for your car, and some cars have flash codes to tell you whats wrong. Most of the check engine light stuff is to let you know that some of your pollution control equipment is not working, and the government want you to get that stuff fixed.

3

A blinking check engine light (as opposed to the CEL simply staying on) is an indicator of a currently occuring condition that can potentially cause further probems. The wise thing to do is to have the problem evaluated and corrected ASAP.

I know that my coolant is too thick…

Too thick? What the heck does that mean?

…and the humidity is the culprit.

Huh? The culprit causing the coolant to be “too thick?” The culprit causing the CEL to be on? Not bloody likely in either case.

Nothing to worry about in the heat, so I let it pass. How do I know? Some grease monkey told me.

“Grease monkey,” huh? Using insulting terms about the people most able to help with your problems is not terribly bright.

Many years ago, I had my timing belt blow out. That’s a bitch to get fixed. $25 part, $8 gazillion in labor. Turns out, if I had gone in right before the belt blew, I’d have saved several hundred dollars in labor.

This isn’t making sense to me. If you had an interference engine, and it bent some valves, there would have been quite a bit more than 25 in parts. Or if it didn’t bend valves, it should have just been a matter of replacing the timing belt, which is the same labor whether or not the belt is broken.

Which brings me to my point. With all the gizmos and technology out there, why in the world can I not get sensors and such galore packed onto my Taurus to tell me exactly what is wrong with my car, at any given moment? Why do I have to take it in to the dealer…?

We’ll let the second insult pass, but note that a competent and well-equipped independent shop can also deal with this–it doesn’t have to be the dealer (with the exception of a few specific procedures).

The sensors and and a microprocessor (the PCM or “computer”) are already in the car. For 2 or 3 grand, you can get a professional grade scan tool to interface with it. The third thing you need is information about and an understanding of the system to evaluate the data from the scan tool. With that, and in many cases further specific testing, you can find out exactly what’s wrong with it.

These systems are far more complex and sophisticated than you seem to realize. There’s a multitude of different ways they can fail. It’s actually pretty amazing that they can monitor their circuits as thoroughly as they do, often storing pertinent failure data. But the only computer that’s really up to the task of processing all the relevant information and arriving at a meaningful diagnosis is the one between the mechanic’s ears.

**It can’t possibly be cost-preventative, can it? A 64-bit processor costs pennies to make nowadays. Cell phones have more technology and infrastructure dedicated to them, and they’re less than a Benjamin ($100 to you squares out there).

What’s the deal?**

Cell phones don’t have to carry all that technology on board. Cell phones don’t have to oversee and integrate the operation of ignition systems, fuel systems, emission control systems, etc. to produce certain desired results under a wide variety of different conditions. Cell phones don’t have self-diagnostic capability. What cell phones have to do is blood-simple compared to what PCM’s and scan tools have to do.

Here are two paragraphs out of a multi-page document that merely explains some of the strategy programmed into these systems (sorry I cannot provide a link):

To effectively detect misfire, the PCM maintains a record of the previous 3200 crankshaft revolutions. These 3200 revolutions are divided into sixteen 200 revolution counters/samples. If a misfire occurs during any given 200-1000 revolution sample that could damage the TWC, the Diagnostic Executive will flash the MIL and set a misfire DTC (refer to figure 5-2).

Emissions-threatening misfire is also monitored in sets of 200 crankshaft revolutions. As shown in
figure 5-3, if the misfire is not constant, the amount of time to set a DTC might be much longer than the catalyst-damaging misfire diagnostic. This is because the misfire must fail five (1000 crankshaft revolutions [5x200]) of the test samples. The diagnostic will constantly monitor all sixteen test samples for any five that may have failed, indicating a misfire and arming the DTC. In a second trip with a failed emissions-threatening misfire, diagnostic tests will set a history DTC and illuminate the
MIL. At this time, the Freeze Frame and Fail Record will be recorded.*

The above sample is one grain of sand out of a whole beach. Automotive electronic control systems are not all that simple.

4

What Gary T said.
In my office I have a quote from former Secretary of Transportation Elizabeth Dole. I’m quoting from memory here so I may miss a comma or two.
**

**
I don’t know the exact date of this quote, but Ms. Dole took office 10 years ago. On the cars I teach on, that is 6 generations of engine management computers ago. Things are way more complex now then they were then. In 1983 our most complex car had 2 computers and a total of 6 fault codes available as a flashing lights. Today our most complex car has 20 computers working in a controller area network (think of a LAN on wheels) with a total of over 1,000 fault codes, with various sub codes (permanent, intermittent, cylinder 1, cylinder 2 etc). Needless to say a flashing light cannot communicate this level of information to a technician. A computerized scan tool, or PC is required to read these codes.

I too will let the insults pass, but I must comment on a couple of the things you said.

Perhaps you should be come acquainted with the most expensive book you have purchased, but have never read. It is called the owner’s manual for your car. Inside you will find a service schedule written by people who know way more about your car than you do. Since you choose not to avail yourself of this valuable information, tomorrow when you shave, you can talk to the person responsible for the additional labor, he will be standing directly in front of you.

Well as you can see from reading what I wrote above, compared to my car, your cell phone is a soup can a piece of string.
Furthermore, they give away cell phones because the money is made in airtime. The car company doesn’t charge you by the minute to drive your car.
Also the technology is, as you mentioned, in the infrastructure. The infrastructure is maintained by professionals, you car is being maintained by a guy who says

Neither of which will trip a flashing check engine light on any car I am aware of.

5

I think another relevant point here is the issue of detection of problems through sensors.
Your car has a large number of onboard sensors that can and will warn you when something is operating out of spec - temperature, pressure, various levels…etc. More expensive cars typically have more sensors - tire air pressure and so on.
To be able to detect every conceivable problem and inform the driver would require a massive amount of dedicated sensors - worn belts would be pretty tricky to monitor electronically for example. A lot of the time the recommended service intervals cover this well, but they assume only a certain level of abusive driving.

The other thing that would be difficult to reliably forsee would be catastrophic problems which cause breakdowns - a stone bouncing up and making a hole in the radiator, for example, or a bearing (like on an air conditioning unit on a serpentine belt) siezing up. These things do not really have any reliable indicators and even if they did the onset is almost immediate so any sensor would be of negligible value.

6

There is a device that can be used to check the condition of the timing belt. It cost a couple of dollars. It’s called a flashlight. :wink: The timing belt should be replaced periodically. I’ve heard every 50,000 miles. The condition of my timing belt is checked every time I get an oil change.

I used to have a Porsche 924. Its CEL would light every 30,000 miles. The mechanic said it was to remind people to get a tune-up. It was reset by pushing a little button at the base of the steering column near the firewall.

I’ve had the CEL come on a couple of times in my Cherokee. Once it was because of a vacuum hose that had become disconnected. Another time it was because of a faulty on-board computer. A third time was because of a faulty “neutral sensor”. (That one prevented me from shifting into 4th – yet another reason I prefer standard transmissions to automatics!)

7

You know, my fist statement might come off as a little snarky. It was just supposed to be amusing.

8

Just to set the record straight, there is no way water can get thick and since the cooling is not evaporative, there is no way the humidity can have any effect on the cooling of engines (though it certainly does on people). The reason the light went off at 71 (although the actual speed is a coincidence) is that much more air was flowing over the engine increasing the efficiency of the convective cooling device known as the “radiator” (it isn’t, at least not much of one). The worst time for engine overheating is when you are stuck in bumper to bumper traffic on a very hot day.