… there’s always a bigger idiot.
The idiot-proof system in this instance is the tire pressure monitoring system (TPMS) in my wife’s car. And the bigger idiot was, of course, me.
To cut to the chase: Happy ending. No lasting damage. Just a cheap and timely tire repair.
But only after a couple of days of pondering why the idiot light on the dashboard had malfunctioned. And whether or not I should just fix it 70s-style (by taping over it), or take it to the dealer.
Not for one moment did it occur to me that this car idiot light might actually be flagging a problem that needed to be fixed.
In this post, for benefit of younger readers, I’m going to explain why old people routinely ignore idiot lights. (Hint: It’s how we were brought up.) Because unless you live through the nadir of U.S. auto engineering — the 1970s — you have no idea just how good modern cars are. And just how much of a joke dashboard warning lights were, to my generation.
1970s auto engineering and the advent of idiot lights.
Source: Vega, left: Motor Trend Magazine. Pinto, right: Ford Division Public Relations, Dearborn, Mich.. Ford Pinto Runabout – 1977. [Photographic Prints]. Retrieved from https://libwww.freelibrary.org/digital/item/53235;
Look at any list of the worst cars ever sold in America, and you will find a whole lot of mainstream 1970s vehicles. The Chevrolet Vega, where the only question was whether body rust or astoundingly excess oil consumption would kill the car first. The Ford Pinto, under-powered and famous for exploding if rear-ended. The Chevy Shove-It, a.k.a., Chevette, with back seats that required you to be a contortionist to access. The AMC Gremlin, arguably the ugliest car ever sold in America.
I could go on.
The decade of the 1970s was a perfect storm of problems for the U.S. auto industry. The first was the Arab Oil Embargo, and the resulting energy crises and shortages of gasoline. This left car makers scrambling to produce smaller, higher-MPG vehicles. The second was the introduction of the catalytic converter, which forced manufacturers to more-or-less completely re-engineer their engines to deal with unleaded gas and with the added complexity of the catalytic converter itself. The third was the string of recessions (or economic malaise) that was the direct result of the oil embargoes and energy crises of the 1970s. Which meant that in order to be sold, cars had to be built as cheaply as possible.
The result was a string of small, cheap, poorly-built cars for which every possible expense had been spared.
And one of the expenses that was cut was the cost of dashboard gauges.
Historically, in addition to a speedometer and gas gauge, cars had gauges for oil pressure, engine water temperature, battery charge or ammeter, and so on. You had gauges for items that were critical to the operation of the engine. You could look at the gauges and check the health of the engine. And if (e.g.) the coolant temperature was climbing, you had advance warning before the engine actually overheated.
The 1970s was the generation of cars in which those expensive gauges were replaced wholesale with cheap warning lights. So now, instead of getting information on (say) engine coolant temperature, when the engine overheated, a red light would come up on the dash. And tell you that your engine had overheated.
These were universally termed “idiot lights”, but there is some controversy over the exact derivation of that term.
The story I learned is that the idiot in question was the typical driver. People were incapable of (or unwilling to) pay attention to standard gauges. And so, warning lights were introduced because, unlike gauges, they were harder to ignore. In effect, the data provided by an oil pressure gauge was replaced with a much simpler message, “hey, idiot, you’re out of oil”. In other words, the lights were introduced because people were too stupid to pay attention to gauges.
In theory, idiot lights would illuminate when there was a serious problem.
In practice, idiot lights would come on for no reason at all. And they were impossible for the average driver to turn off. In all the years that I and my friends drove those cars, I never heard of an idiot light actually coming on at the right time and preventing damage to the vehicle.
Instead, it was common knowledge that when your idiot light came up, that signaled that the idiot light was broken. (Or, on rare occasions, it actually functioned correctly and told you that you had just damaged your engine beyond repair.)
And literally the only fix for a broken idiot light, available to the average U.S. driver, was to block the idiot light so that you couldn’t see it. Black electrician’s tape being the product of choice for that purpose. But Magic Marker or Sharpie would do for an ultra-low-effort fix.
You had an entire generation of Americans, driving crappy little cars, with little pieces of tape covering the universally-useless dashboard idiot lights. I couldn’t make stuff like that up.
And for that generation, the absolute and immediate gut reaction to any idiot light on the dash is, oh, the idiot light must be broken. Because that’s literally all we ever saw in our youth. Only after considerable reflection might it occur to one of us that maybe the idiot light is signalling a problem.
Fast-forward to the modern check engine light.
Unless you lived through that era, you just can’t appreciate how much better cars are now. Materials, rustproofing, engine life, gas mileage, safety, convenience, reliability. All of that is vastly better now than in the 1970s.
In particular, the US EPA-mandated On-Board Diagnostics (OBD) system really changed the game for car maintenance, including idiot lights. That was introduced in the late 1980s in California, and the modern (OBD-II) system was mandated for all U.S. vehicles starting in 1996.
That’s had two implications.
First, if you want old-style gauges, instead of simple idiot lights, you can easily add them via devices that plug into your car’s OBD-II port. For years, I drove with a ScanGauge plugged in, so that I could see things like engine temperature, engine load, and instantaneous gas mileage.
Second, in general, idiot lights are mostly reliable now. If your check engine light comes on, that pretty much guarantees that something is actually wrong with your engine. And not with your idiot light. Sure, sensors can fail, and so on. But I’d say that on the typical modern car, when an idiot light comes on, the odds are overwhelming that it’s flagging a true problem with the car.
But the tire pressure monitoring system light is an exception. In some (but not all, see below) cars, those monitoring devices are battery powered, and sit inside the tires. As cars age, the batteries die, turning on the TPMS warning light. Replacing them required dismounting the tire from the rim. So a lot of people end up simply ignoring the TPMS light, and instead check their tire pressure manually from time to time.
As a result, the TPMS indicator is the last of a proud tradition in U.S. auto engineering. It’s an idiot light that typically tells you that the idiot light is broken. That’s going to be true mostly on older cars, where it’s just not worth the expense of replacing the worn-out tire pressure sensors.
But on a new car, you can’t blithely dismiss the TPMS idiot light. Eventually, this dawned on me, I checked the tire pressures, and sure enough, I had picked up a nail in one tire, leading to a slow leak. And then to a quick and cheap repair at my local tire shop.
TPMS: You still have to check your tire pressure.
Just to up the intellectual content here, note that TPMSs work in various ways.
One system is an “indirect” TPMS. It uses the car’s wheel speed sensors to estimate the diameter of each tire. An under-inflated tire will have smaller diameter and so will spin slightly faster. If the wheel speeds differ enough, that will eventually trigger the TPMS warning light. These indirect systems have no hardware that requires periodic replacement. but they may require (e.g.) re-calibration each time you rotate, change, or inflate your tires.
The other approach is a “direct” TPMS. These literally include battery-powered air pressure sensors in each tire. Our car (Toyota Prius) uses direct sensors. As with the indirect system, if the car senses low air pressure in a tire, it turns on the warning light. For direct TPMS, you have to replace the battery-powered sensors when the batteries die.
But in either case, your tires can get pretty low before that TPMS light will turn on.
With a direct TPMS, any tire that is more than 25% under-inflated will trigger the light. For a typical 35 PSI passenger tire, that means you have to be under-inflated by 9 PSI or more to trigger the light. That degree of under-inflation will cut your gas mileage and induce excess tire heating and wear.
Worse, many indirect TPMSs will not notice a problem, at all, if all the tires gradually go flat at the same rate. If you never check your tire pressure, you can end up with four grossly under-inflated tires. As long as they are all under-inflated by about the same amount, your TPMS light can remain dark.
The moral of the story is that the TPMS does not fully relieve you of the burden of checking the air in your tires. Every so often, you still need to pull out a gauge and check them the old-fashioned way.
The icon-challenged generation and the snowflake trapezoid of doom.
Today, the proliferation of idiot lights, coupled with manufacturers’ unwillingness to use text labels, results in what I can only describe as icon overload. Instead of idiot lights for a handful of key functions, with text labels like “oil”, you now have a dashboard populated with dozens of itty-bitty unlabeled icons.
As the driver, a) you have to notice when one of those little lights comes on, and b) you have to be able to interpret what the icon means. Preferably without having to pull out the owner’s manual.
And sometimes, I have a hard time figuring out what the little icon is supposed to represent.
I am not alone in this.
One of my brothers drives a Prius. The first year he owned it, he thought it was periodically malfunctioning. A yellow warning light would appear on the dashboard. The icon was an elongated trapezoid, with some sort of star-shaped symbol at one end.
But the car seemed to run fine. So, as is typical for persons of my generation, he dealt with it by ignoring the idiot light. He dubbed it the snowflake trapezoid of doom, and kept on driving.
Turns out, that was the Prius frost warning indicator. It’s supposed to represent snow on a roadway, and comes on any time the outside temperatures are below 37 F. To hear him tell it, my brother owned that car for several months before he finally figured out what that icon was supposed to represent.
And, really, I can’t blame him. Even now, I look at the array of icons apparently standard on modern Toyotas, and some of them still leave me shaking my head.
Source: Brent Toyota.
I’m sure those are all completely obvious to some of you, but I have a hard time even guessing what the (e.g.) car-on-a-lift one is for, or the P ! icon. What’s the gear with an exclamation point for? And so on. All of these must have made sense to some Toyota engineer somewhere. But I’d still need to consult the user’s manual to know what some of them are supposed to be telling me.
