Written by Randy Gerdin on March 1, 2016
Our cars and trucks have always had dash warning lights. The common ones were the red “Oil” light, the red “Engine Overheat” light, the red “Brake” light, and the red “Battery” light. Notice that all the lights in the past have been red, and red means STOP. Because if you did not stop, it usually would cause engine damage to the vehicle or the engine would not stop but may stall out. We still have these same lights and they are still all red. Late model vehicles now have these lights plus many more. Sometime, try turning on the ignition switch but not starting your vehicle. Take a look at all the different lights that come on. The reason the vehicle turns them on is to do a bulb check. So if you do not see, for example the red oil light, come on, you may want to get it checked out to see why. If you would lose oil pressure while driving and not be notified by the red light, most likely, it would ruin the engine.
The problem these days is there are so many lights of various colors that may come on that it is confusing for the driver to understand. In many cases, people just ignore the lights. There are a few additional lights that come on only while the engine is cranking over as you start it up. Again, these are bulb checks so you can make sure they do indeed come on. Many people do not understand all of the lights and they are ignored. One phenomenon I have noticed lately is that most people do not even pay attention or have a concern when a dash light comes on even while driving. The other day I test drove a customer’s car and the check engine light, low coolant light, brake light, tire pressure light, traction control light, anti-lock brake light, and air bag lights were all illuminated on the dash as I was driving down the road. When I mentioned this to the owner, they were not concerned. I guess it is their vehicle and they can do what they please. However, dash lights do not come on unless there is something wrong.
Some lights are safety related, others are maintenance related, and some may even cause damage to a major component of the vehicles. Some folks go to the internet to find out how to get these annoying lights off. Some folks have the code readers or stop by a parts store to have the code read and then go to numerous websites that say they can tell you what the code is and how to fix the problem. I am always wary of these types of things. We have had folks drop off their vehicle and tell us to install a certain part. We ask if they want us to diagnose the problem and they tell us that they have checked it out and they just want the part replaced. In most cases, we put the part on and the light is still on, and now they have spent good money on the repair and must decide to have the vehicle properly diagnosed. Our approach has always been to inspect and test to the proper conclusion rather that just replacing parts and hope we hit the problem.
We have had vehicles where the owners have spent hundreds of dollars in parts and then finally will bring it in for a proper diagnosis. Usually the trial and error method is the most costly. Some folks do not realize the ramification of a light being on. For example, if an air bag light were on, the air bags would not deploy in the event of a crash. This could be very serious for the occupants. If the anti-lock brake light is on, the anti-lock brake system will not activate in the event of an emergency stop, again this could be very dangerous. If the check engine light is ignored, especially if the light flashes, this could cause anything from increased emissions to excessive fuel usage to damage to a major component. Usually these light are amber in color. This indicates “caution”. You may continue to drive but the vehicle should be inspected as soon as possible.
You may not notice any difference in how the vehicle performs when some of these lights are illuminated, because the computers will try to compensate for certain conditions so you may drive them in for service. In some cases, the vehicle may go into “Limp In Mode” which will severely restrict vehicle operation, but allow you to get to someplace safe so you can properly take care of your vehicles needs. Really, that is a good thing for you; otherwise you may not know there is a problem until it is too late. I Hate When That Happens!