Lesson 3: Dashboard Gauges & Lights

The instrument panel on your dashboard has multiple gauges and indicators. These may include the fuel gauge, speedometer, tachometer, oil pressure, and engine temperature. Most are self-explanatory– the speedometer measures your speed, etc. The one that may not be self-explanatory is the tachometer, which indicates engine speed in revolutions per minute (RPM). It often has a red zone which you should never exceed.
In the previous lesson we checked all the vehicle lighting which included the dashboard symbols. Now we’ll discuss what these symbols mean. As always, a better resource to learn the meaning of each dashboard symbol for a specific vehicle is the owner’s manual for that vehicle. The ones that are included in each vehicle will vary by make and model.

Dashboard lights can be red, orange, yellow, green or blue. Traditionally the red lights are more severe and when a red light comes on while driving, it means you should immediately pull over safely and call a tow truck. However there are some exceptions – some lights which are generally red can be yellow or orange, and some red lights can be fixed immediately (if the Seat Belt Light is on then put on your seat belt, if the Door Ajar Light is on then close all the doors). Orange or yellow lights generally indicate that there is a problem with your vehicle, but it is safe to drive to a repair facility or your home residence to investigate further. This also has some exceptions. Green and Blue are generally just indicator lights that tell you something is on or that a system is working (like the blinker lights, high beam lights, or cruise control). It is always best to consult the owner’s manual for a particular vehicle, and for illustrations of the lights on your dashboard.

The following are some common dashboard indicator lights:

Airbag Light or Supplemental Restraint Warning Light

Red, Orange or Yellow. Whenever this light illuminates the air bag system senses a problem, which could be a safety issue. It doesn’t necessarily mean that the airbags will not work. The airbags might or might not still deploy during an accident. The light means that there is a part of the airbag system that may not work.

Anti-Lock Brakes Light

Orange or yellow light. This indicates a failure in the anti-lock brake (ABS) system and anti-lock brakes are disabled. The purpose of the ABS is to allow steering control of a vehicle while braking and to avoid skidding during a panic stop. If this light is on, then normal conventional brake function will continue. If it’s on in the event of a panic stop then the vehicle will skid. Have the vehicle serviced.

Brake Light

Red light, if it illuminates while driving then immediately pull over safely and have the vehicle towed. (If it’s on before driving and is shared with the parking then disengage the parking brake). This light indicates that there is something wrong with the brakes. There could be a low brake fluid level, there could be a hydraulic brake failure, or the parking brake is engaged.

Change Oil Soon

Orange or yellow light. This light indicates that routine oil change and maintenance is due. It’s based on revolutions of the crankshaft, which is even more accurate than basing routine oil changes on mileage.

Check Engine Light

Red, orange or yellow light. There is a problem with the vehicle emissions and the vehicle’s computer will have diagnostic trouble codes (DTCs) which will be retrieved when the vehicle is inspected. The light may come on and then off. If there are any performance issues with the way the vehicle is driving, then pull over and have it towed. If the light comes on and stays on, or comes on and then flashes during acceleration, then immediately pull over safely and have it towed to a shop. Don’t confuse the check engine light with the “service vehicle soon” light below.

Door Ajar Indicator Light

Red light. One of the vehicle doors is open. Close the open door before proceeding to drive. There may also be a separate light for the trunk.

High Beam Indicator or Brights

Usually blue, but can be red on older vehicles. This indicates that your brights are on.

Low Coolant Level Light

Red, Orange or yellow light. This light indicates that the engine coolant level is low, which could be due to a leak. It is still safe to drive as long as the engine temperature light is not on. In some vehicles the first symbol above, the thermometer symbol, can also be a temperature light. (Remember from Lesson 2 that the coolant level should not be checked while the engine is hot). Some vehicles can have a blue thermometer symbol. Consult the owner’s manual for its description.

Low Fuel Light

Yellow or Orange. This light indicates that fuel is low. It could also be a simple round light that illuminates when the fuel gauge is nearing empty.

Low Oil Level Light

Yellow or Orange. The oil level is low. Refill the oil as soon as possible and bring the vehicle to a shop to see why it was low.

Low Oil Pressure or Engine Oil Pressure Light

Red light (immediately pull over safely). Once you pull over you could check your oil level and add oil if it’s low. If the light continues illuminated then you should have your vehicle towed to a facility. Catastrophic engine failure will occur if the oil pressure is low. Repairs for these damages can be very expensive.

Parking Brake Light

Red light. The parking brake is engaged or not fully released. Release it completely before driving.

Service Vehicle Soon

Yellow light. This light may be used in conjunction with other lights. Depending on which other lights are illuminated, there may be a problem with the anti-lock brakes (ABS), brake hydraulic system, traction control system (TCS), or the electronic suspension system. Don’t confuse with the “Service Engine Soon” light, which is one of the possible check engine lights shown above.

Temperature Light or Hot Engine Light

Red light (immediately pull over safely, turn off the engine, and have it towed). This light means engine temperature has exceeded maximum parameters. Severe engine failure will result if you continue to drive. For a few extra moments while you’re finding a safe place to pull over, you can turn on the heater to high, which dissipates heat from the engine. If the heater does not work, it is an indication that the coolant level is low, and that the vehicle should not be driven. The dashboard may also have a temperature gauge which has a thermometer symbol.

Throttle Control Warning Light

Yellow or orange. In some vehicles the throttle has an electronic control system. These lights indicate that there is a problem with the system. Have the vehicle serviced as soon as possible. In some makes and models the wrench light can be for other purposes. Be sure to consult the owner’s manual.

Tire Pressure Warning Light

Yellow or orange. This light indicates that one or more of the tires has fallen below 25% of the recommended pressure. Have the tires checked soon.

Turn Signals and Hazard Light Display

Usually green. These will only illuminate when a turn signal (left or right) or the hazard lights (both simultaneously) are turned on. If one stays on instead of blinking in rhythm or blinks slower or quicker than usual then there is a problem. One of the bulbs may need to be replaced or there is something wrong with the circuit.

Charging System Light or Voltage Light

Red Light. If this particular light illuminates while you’re on the freeway then you may be able to proceed to the next exit. This light indicates that voltage is below the minimum specification and your vehicle will stop running once the battery dies. Safely pulling over and having the vehicle towed is even more important at night since you’ll lose the use of your headlights, which tend to drain the battery even quicker. Some of the samples are yellow; in this case you should still treat it as a red light.

Security Light

Red, Orange or Yellow. This indicates that there is a problem in the theft deterrent system. Sometimes the vehicle will not run if this light illuminates or blinks.

Seat Belt Light

Red light. This means that the driver and/or passenger do not have their seat belts fastened. Put on your seatbelts before continuing to drive. There is a reason why they show videos of people in car accidents to Driver’s Ed students. They want you to understand that when you get behind the wheel you’re potentially putting people in danger. Ideally, seat belts would be more like the harnesses used in roller coasters, which include two shoulder straps and a middle fastening device at the chest. The cross-over shoulder strap isn’t very effective in comparison. It is designed that way for commercial purposes and to account for common human behavior. It’s easier and quicker to have one buckle where the belt can be pulled over and fastened in one quick motion while the person is just getting into the car. While the conventional seat belt isn’t 100% efficient, it is potentially the most important safety feature of the vehicle because it keeps the body harnessed and kept in the seat. Wear your seat belt!

Traction Control Light or Low Track Light

Yellow, orange or blue light. This indicates drive wheel speed is higher than the coasting wheel speed. For example, if you have front wheel drive, then the front wheel speed is higher than the rear wheel speed. This can be useful on ice, dirt or any low-traction condition. Be careful while driving in these conditions, especially when turning.

Once again, this is just a sample list. Your particular make and model could have other lights and/or it won’t include all the lights listed above. Consult the owner’s manual. See also the Warning Light Guide on the Crawford’s Auto Repair website: https://crawfordsautoservice.com/dashboard-indicator-light-guide-free-warning-light-code-scan/.

Lesson 3: Dashboard Gauges & Lights is one of twelve lessons that are also available as a free ebook download which is complete with illustrations. These lessons are based on the outline for the Boy Scout Automotive Maintenance merit badge and adapted by Crawford’s Auto Repair for a general audience. This article is for informational purposes only and the author does not assume responsibility or liability for any accident that may occur when working on motor vehicles. By reading this page you accept the condition that you are ultimately responsible for your own actions.

Copyright © 2014, Jeff Crawford. Permission is granted to republish this article for personal or commercial use as long as the content, citation, and copyright notice all remain intact and unchanged. There must be an active “follow” link to CrawfordsAutoService.com.

Lesson 3: Dashboard Gauges & Lights is licensed under a Creative Commons Attribution-NoDerivatives 4.0 International License.