What is the Horseshoe-shaped Dashboard Warning Light?
Its cold weather time again and time again to speak about the Tire Pressure Monitoring System (TPMS), and its associated warning light(s). Every year several million more drivers who have recently upgraded their cars will encounter the light for the first time.
These are two versions of the TPMS light, and either one is easily the most misunderstood warning light you’ll find on your instrument panel. And the fact that its shaped like a horseshoe doesn’t help.
First, unlike other yellow/amber lights, there is nothing wrong with your car — it presents you information about your tires and likely as not there’s nothing actually wrong with them either.
Why the Light Is On
There are two possible reasons why you are seeing this light. First, as the weather cools the most likely possibility is that all four of your tires are low on air (and/or the spare!). The second possibility is that one tire has a leak of some sort, but we’ll return to that in a moment.
Air expands when heated and contracts when cooled. Air that has cooled and contracted in your tires leads to reduced tire pressure. The warning light comes on and air needs to be added to your tires. Its important to note that air has not actually leaked out.
But the warning light does not discriminate between cooling air and actual air leaks. It comes on if one tire is low or all four is low, so more information is needed. Your model may or may not include a display option like the one shown. It is a read out of the tire pressure in the individual tires. If all four tires read roughly the same, within a pound or two, the warning light is the result of seasonal cooling.
And while on the subject, a thought for manufacturers. Every vehicle equipped with the tire pressure warning light simply must be equipped with this display. Leaving your customers in the dark by displaying the warning light only is unacceptable to us.
Now, if one tire is several pounds lower than the others, 5, 6 or 7 pounds or more, that tire is leaking and needs to be serviced as soon as possible.
If your vehicle is one that features only the warning light, the tire pressures need to be checked by hand to determine the cause — a single leak or seasonal reduction in all four.
If you’re not comfortable checking your tire pressures or with filling them, the good news is that pretty much every tire store, repair shop or car dealer will fill them for you at no cost. Its simple for them to do and they make a friend in the process, meaning more business from you down the road. Please drop in on one of them.
If you are comfortable with checking your tire pressures and adding air, by all means do so. But you will first need to know the required tire pressure. Look for a label just below where the driver’s door latches. The required pressures will be shown. They will match left to right but will likely be a little different front to rear. Set the pressure on the pump and trust it. It will stop pumping once the proper pressure is reached. You may also find yourself using a pump with a built in gauge. Trust it as well and be sure to add your spare tire to the routine.
Each tire valve has a cap that needs to be unscrewed and removed. Don’t lose it — it keeps water and dirt out and will keep the valve from developing a leak.
Learn more about this warning symbol here.
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Remember that only proper service and repair procedures will ensure the safe and reliable operation of your car. In addition, proper safety procedures and precautions, such as the use of safety goggles, the right tools and the equipment should be followed at all times to eliminate the possibility of personal injury or improper service which could damage the vehicle or compromise its safety.
These posts are for information sharing purposes only, and should not be used in lieu of an OEM service manual or factory authorized service procedure. We are not in the auto repair business nor do we publish automotive service manuals. Nothing we include on these pages and posts has been reviewed, approved or authorized by any vehicle manufacturer.
Technology is always changing and what is current and accurate today may be literally out-of-date and inaccurate tomorrow. And when it comes to the current state of flux in the auto industry, nothing is more true.
The author has 25 years of automotive experience and has assembled the most extensive collection of symbols and warning lights anywhere (over 1,000!) and can help you open and start any keyless start car with a dead key fob battery. BA, St. Joseph’s College, ME: MS, Rensselaer Polytechnic Institute, NY
This symbol is a Brake Trouble Indicator symbol. They could indicate a serious problem with the brakes. However, the light will also be on when the hand, or emergency, brake is engaged.
This symbol is a Parking Brake Indicator. There are a number of considerations. The symbol to the right simply indicates that the parking, or emergency brake is engaged. Be sure to disengage the parking or emergency brake before driving.
One of the first idiot lights, this warning light features an old-school oil can. It is the Oil Level or Oil Pressure warning lights or symbol. A wavy line below the oil can indicates the oil level is low. Without the wavy line, your engine is telling you that the oil pressure is low.
There are several versions of the dreaded Check Engine Light, and this one is the most common. It is one of the oldest of the symbols that you may see. The word “Check” may appear inside the image, or below, or not at all.
One of the original idiot lights, at least in red, this is the Temperature Warning light or symbol. In red, it indicates quite simply that the engine temperature is too high. If you see this light, your vehicle should be stopped and the engine turned off as quickly as possible. Turning on the heater to the highest setting will remove some of the heat as well. Contact your dealer or authorized service center as soon as possible.
This is the Master Warning Light symbol, in red. If this light is on, there will likely be text displayed as well on the instrument panel, or another warning light. Look for text in particular. It could very well point out something as serious as low oil pressure. However, despite the serious look to the symbol, it is generally associated with simple reminders such as a door ajar or that it is time to change the oil.
This is the Tire Pressure Monitoring System (TPMS) or Tire Pressure Monitor (TPM) warning light symbol. It is also used as Flat Tire Monitor (FTM), which seems redundant. The tell-tale comes on when the inflation on one of the tires is reduced about 25% or more. In most cases, that will be about eight pounds. This is easily the most misunderstood symbol you will ever see on your instrument panel.
The image of a car with squiggly or wavy lines behind it is the Slip Indicator symbol. When a vehicle detects slippery conditions, its stability or traction control system is activated. The light will flash, irregularly in some vehicles, indicating that the system is doing its work, helping to keep the vehicle in control.
This is a Reduced Engine Power Indicator. Only a handful of manufacturers use this light, which comes on automatically with a reduction in the vehicle’s performance. Given what is likely an obvious reduction in power and acceleration, the symbol itself becomes redundant. The image is the same one used for the Check Engine Light above, with the added arrow pointing down.
This combined system warning indicator covers the Electronic Stability Program (ESP) and the Brake Assist System (BAS). These systems work together, and a fault in either, or both, will cause the light to come on. If it remains on, see your dealer or authorized service center.
This is the primary Key Fob Indicator. A number of picture symbols are used to indicate the presence of an electronic key in a push button or, ironically, keyless start, or keyless ignition, vehicle. These systems will allow a vehicle to be started only when an electronic key is present in, and detected by, the vehicle.
This is an Intelligent Brake Assist (IBA) Off Indicator symbol. IBA uses lasers to identify approaching obstacles and applies the brakes accordingly. The light comes on when the IBA switch is turned off. If the light comes on while the system is on, it is either unavailable temporarily or is malfunctioning. Check that the laser sensor is clean, when it is safe to do so.
Cruise Control Indicator light in text form. This light is illuminated when the cruise control is engaged. It is perfectly straightforward, as opposed to the two image symbols below that are now often used in its place.
This is the most common Check Gas Cap Indicator symbol. It is one of the few things the average driver can do anything about. The image, which is really half of a car with an unscrewed gas cap, can look like a water pitcher with a screw or bolt next to it.
These are Park Assist Indicator symbols. The green version will be visible when the system is activated and working. The manufacturer may refer to this as Intuitive Parking Assistance, Park Distance Control (PDC), etc. It looks like a sail with lines radiating from it!
This is a Low Windshield Washer Fluid Indicator symbol. Fill the windshield washer fluid reservoir as soon as possible. The image actually resembles an open hand-held fan, which is supposed to be the windshield. The dashed lines represent two steams of water.
The acronyms AFS and AFLS in these symbols or indicators stand for Adaptive Front-lighting System or Adaptive Front Lighting System. The difference is very subtle and is the result of a manufacturer choice only.
This symbol is a Tail Light Indicator symbols. The replacement of a light bulb or two will restore order. Some manufacturers add a text message in the instrument panel noting exactly which light is out. The symbol is often described as eyelashes coming out of the back of a car!
This symbol is the High Beam On indicator. The light is active only when the high beams are active (turned on) and has been a standard in vehicles for decades. It is one of only a select few presented in a blue color.
This the Fog Lamp Indicator symbol. The indicator in green is active only when the fog lamps are activated. The wavy or squiggly line crossing straight ones is meant to indicate light passing through the fog.
These are Headlamp Out Indicator symbols. One or more of the headlamp bulbs is burned out or malfunctioning. This is another symbol that may utilize an exclamation point, which always indicates a problem, even if its in the green color. Another symbol in yellow/amber only is an alternative Lamp Out indicator.
For instance, the check engine light uses the image of an engine configuration that is rarely if ever seen anymore. A belt driven fan on the front and an air cleaner on the top.
The oil light uses an image of an oil can that hasn’t been seen in 50 years. We went looking for images of this style oil can and found one — literally old and rusted. Drivers interpret warning lights through the filters of their own experience, and this one is more easily associated with a Aladdin’s lamp. Thank the movies and tv.
And then there’s the tire pressure warning or TPMS light. Again, it is meant to be easily recognized and understood, but its a slice of a tire! Who’s ever seen a slice of tire? Using their own experience, drivers calling service departments I’ve worked in have called this an exclamation point in parenthesis or brackets, an exclamation point in a horseshoe, flames – destined to be a classic! Remember, the light is a yellow amber color.
An Actual Slice of a Tire!
Finally, there are a handful of cars that use this symbol instead, so be aware! Its still a cutaway of a tire, and somewhere along the line it was decided that the exclamation point would be more easily understood.
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4)
Adaptive Cruise Control
functions of today’s vehicles and understand what they do. It is a greater wonder that they recognize its associated warning light! Seriously, does the
A word on tire pressure and tire pressure gauges
So its that time again. Time when the weather cools and your tire pressure drops, as directed by nature, and you’ll soon see the Tire Pressure Monitor System (TPMS) light. The one that looks too much like a horseshoe.
Set the pressure, 36 lbs in the case of the EV, inflate the tire and the pump stops and beeps when it reaches the the pressure that’s been set. I then check the accuracy of the pump with my pencil type pressure gauge. It read 34 lbs on each tire.
Now one might think that powered system like the pump I used might be more accurate, but this is clearly not the case. And while I do recognize that 34 lbs is quite literally close enough, getting to 36 lbs will stave off the next need to fill again as the temperature continues to drop by a few degrees.
And of course, 2 days later its 60° and all 4 tires are at 36 lbs…
Keep it simple and stay with the mechanical gauge and its easy to carry. And do back-up the pump and check what’s actually gone in to your tires.
For more tire pressure, check our TPMS page.
——————————————————————-
Remember that only proper service and repair procedures will ensure the safe and reliable operation of your car. In addition, proper safety procedures and precautions, such as the use of safety goggles, the right tools and the equipment should be followed at all times to eliminate the possibility of personal injury or improper service which could damage the vehicle or compromise its safety.
These posts are for information sharing purposes only, and should not be used in lieu of an OEM service manual or factory authorized service procedure. We are not in the auto repair business nor do we publish automotive service manuals. Nothing we include on these pages and posts has been reviewed, approved or authorized by any vehicle manufacturer.
Technology is always changing and what is current and accurate today may be literally out-of-date and inaccurate tomorrow. And when it comes to the current state of flux in the auto industry, nothing is more true.
The author has 25 years of automotive experience and has assembled the most extensive collection of symbols and warning lights anywhere (over 1,000!) and can help you open and start any keyless start car with a dead key fob battery. BA, St. Joseph’s College, ME: MS, Rensselaer Polytechnic Institute, NY