A mysterious, yellow electronic symbol
Oct. 27, 2014
by Mark Ollig

While starting my car last week, I was surprised by the sudden appearance of a brightly illuminated, yellow icon symbol, just above the speedometer gauge.

Since getting the new car, I’ve learned several of the informational symbols in it, but this one puzzled me.

There I was, sitting alone in my car, staring at this unfamiliar yellow indicator light, pondering what it meant.

A bright yellow exclamation point was in the middle of what looked like two slightly bulging, yellow parentheses connected to a flat, linear baseline. This baseline had four black parallel rectangular squares etched half-way through.

“Could this symbol mean I need more oil?” I wondered.

“It can’t. I just had the oil changed. Maybe there’s a leak,” I said to myself.

I opened the glove compartment, found, and briefly flipped through, the heavily-paged car owner's manual.

Becoming somewhat impatient, I decided it would be quicker to just call the dealership where I purchased the car.

Speaking with their service department, I described this mysterious, yellow icon symbol, and asked if I could stop in to have them look at it.

“No problem, someone will help you when you arrive,” they confidently said over the phone.

I felt reassured, but somewhat embarrassed; however, since it was such a strange-looking symbol, I thought it might be important, and wanted it checked out right away.

I can hear some of you giggling out there – because you know what this yellow icon symbol means, don’t you?

Remember folks, this is my first new car of the 21st century; I had been driving a 20th century Ford Police Interceptor for many years.

The Interceptor used simple-to-understand analog gauges and icons, which, when illuminated, had a name associated with them, not symbolic codes requiring a specialized decrypting degree in order to understand what they meant.

Fortunately, the car dealership was close by.

As I drove towards their service bay door; it suddenly opened, and a smiling service person inside appeared and waved me in.

“So, let’s take a look,” he said, while checking the instrumentation cluster panel with the yellow symbol still brightly shining.

“Ah, you have low air pressure on one of your tires,” he knowingly said to me.

“So, that’s what it is!” I exclaimed.

It seems the yellow icon I saw symbolized the cross-section of an under-inflated tire; the exclamation point gave emphasis to the low tire pressure.

My car model has an air-pressure monitoring sensor in all four tires, but determining which tire has the low pressure requires one to individually gauge each tire’s air pressure.

Some car models have an icon symbol displaying all four tires, with the current air pressure number for each; any tire with low air pressure is highlighted.

The next car I get will definitely have this.

After the service person measured the air pressure in all four tires, it was determined the front-right tire was the one with the low tire pressure.

This tire was taken off and inspected.

It was found to have a nail in it; as a result, the air was slowly leaking out.

The yellow icon symbol which was activated is called the TPMS (Tire Pressure Monitoring System) alert indicator.

A TPMS sensor is mounted inside each tire rim, and includes a battery.

When a tire’s air pressure low threshold setting is crossed, the sensor will activate the yellow dashboard TPMS symbol, using a low-frequency radio signal.

The TPMS battery is encased inside each tire pressure sensor device, and has a life expectancy of approximately five years. When this battery becomes low, the yellow tire pressure indicator symbol will flash, and the dealership (or the mechanic in the family) will need to replace the entire sensor unit, and reset its threshold settings.

Yours truly logically reasoned when one tire battery sensor is low, the other three probably are too, and so, this tire-pressure-aware columnist, would have all four TPMS sensors replaced.

The TPMS alert no doubt saved me from ending up with a flat tire on the highway, or worse, a tire-blow out, which could have resulted in a crash.

So, I am therefore thankful for having the TPMS installed.

Having correct tire pressure improves fuel economy, lengthens a tires road life, and most importantly; increases safety by avoiding accidents caused from under-inflated tires.

The National Highway Traffic Safety Administration’s TPMS mandatory compliance date was enacted for all new light-motor vehicles sold after September 1, 2007.

The “Federal Motor Vehicle Safety Standards; Tire Pressure Monitoring Systems; Controls and Displays” webpage is: http://tinyurl.com/nb5mur4.

The internationally recognized TPMS low-pressure warning symbol can be viewed from my online photobucket collection at: http://tinyurl.com/kjdbd95.

By the way, I found the low tire pressure warning icon symbol, and its description, on page four of my car owner’s quick-start guide brochure.

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