Dashboard Warning Lights - Understanding What They Mean & How To Act

There’s a lot going on when you are driving a heavy duty truck. You need to make sure everything in your truck is running smoothly to avoid potential disasters.
Your next loading dock is 45 minutes away. With a quick glance at the Dashboard Warning Light, you notice the fuel level is low, and the tire inflation light is on. Should you pull over to fuel up and check out the problem or is it safe to continue driving?
While some Dashboard Warning Light lights and instruments indicate emergency situations, others notify the driver of issues that could be concerning if they aren’t serviced soon. Heavy duty trucks are complicated and have a lot of moving parts, and for this reason there are many more Dashboard Warning Light symbols and gauges that truck drivers have to keep an eye on.
To keep trucks in normal operating condition, drivers should understand the function of each panel control so they can detect and call in any complications. Here is a guide to help you understand what your truck Dashboard Warning Light symbols, gauges, and warning lights mean.
Note: The following gauges and warning lights are on all heavy-duty dashboards. Please refer to the vehicle’s operation manual to learn about controls specific to your truck.
You will figure out the urgency of the Dashboard Warning Light situation by the colors light up!

RED = danger → stop immediately and call dealer or road service!
YELLOW = caution → check the type of warning light and ask your dealer for advice ASAP
GREEN = safety → this light is a sign of safety, please drive safely!
The icons and colors are determined by the International Standards Organization (ISO) and are the same for all cars in the world. So, once you learn them, you’ll never have to worry about changing cars!

Common Truck Gauges

Truck gauges provide drivers with vital information about the state of their truck and how it is functioning. All heavy duty truck Dashboard Warning Light have the following truck gauges.

Odometer:

All vehicles have odometers, including heavy duty trucks, so most drivers are familiar with this Dashboard Warning Light gauge. The odometer shows the total mileage on your truck, and most odometers can also show the mileage of a specific route you have taken. This information is useful for knowing when your truck needs an oil change and other routine truck maintenance.

Voltmeter:

This truck gauge shows the charge of your battering, either with numbers or with three colored sections. If your truck has a numerical voltmeter, it will read 14 to 14.5 volts when your battery is fully charged while your engine is running. This is the range your battery should typically stay in. If your voltmeter consistently reads below 14 volts or over 15 volts, then your batter is under charged or over charged, respectively, and you should have a diesel mechanic check your system.
If your heavy duty truck has a colored voltmeter, you want the needle to hover in the middle green area. If it is in the red area to the left, then your battery is under charged, and if it is in the red to the right, then your battery is over charged. Keeping an eye on your voltmeter will alert you to charging issues before they turn into serious problems.

Tachometer:

The tachometer measures the engine’s speed in revolutions per minute (RPM). Today’s diesel engines are designed for maximum peak torque at lower RPMs.

Fuel Gauge:

The fuel gauge is a vital auto and truck gauge in all vehicles. It lets you know how full your fuel tank is. Heavy duty truck drivers should check their fuel gauges regularly so that they can be sure they have enough diesel to make it to their destination. Running out of fuel while on the highway is a less than ideal situation that you want to avoid at all costs.

Engine Oil Pressure Gauge:

The engine oil pressure gauge allows you to keep an eye on your heavy duty truck’s oil pressure. You want the oil pressure to stay between 30 and 70 pounds per square inch, or PSI. If your oil pressure is too low, your engine can suffer serious damage.

Air Pressure Gauge:

This truck gauge monitors the PSI of each truck reservoir. You should regularly check both your primary and secondary air pressure gauges to make sure they do not fall below 90. If this happens, there could be a leak or some other problem with your air brake system. Pull over as soon as you can before your heavy duty truck experiences a breakdown.

Temperature Gauges:

Heavy duty truck Dashboard Warning Light have a number of different temperature gauges. Some temperature gauges should be high while others should be low. Keep an eye on all your temperature gauges to keep your truck performing as it should be. The following are the different types of temperature gauges you will see on your truck dashboard.

Coolant – Shows the coolant’s temperature. Average engine temps vary but are usually between 165-195 degrees Fahrenheit. If the coolant is too hot, you should pull over at the next safe location, let it cool down, and check the manual to verify normal temperatures (many heavy diesels have 195 thermostats in them).
Engine Oil – This gauge shows the temperature of your heavy duty truck’s motor oil. If your oil is too hot, your engine can be damaged.
Pyrometer – This gauge displays the temperature of your diesel engine’s exhaust. This can warn you that your heavy duty truck may have engine damage.
Transmission – The temperature of your truck’s transmission is shown here. You can find out what a normal transmission temperature is in your manual. Normal temperature ranges vary by manufacturer.
Rear and Forward Axles – The temperature of the oil in your axles is shown here. Forward-rear and rear-rear axle oil temperatures should stay around 160 to 220 degrees Fahrenheit (71 to 104°C) for Meritor axles or between 80 and 200 degrees Fahrenheit (82 to 93°C) for Dana Spicer axles. When your heavy duty truck is under heavy loads or climbing steep grades, it is normal for these axle oil temperatures to go up, as long as the temperature falls back to normal afterwards.Be sure to check the manual to verify normal temperatures for your specific vehicle.

Dashboard Symbols and Dashboard Warning Light

Heavy duty truck dashboards have a variety of warning lights and dashboard symbols that can indicate both emergency and non-emergency issues. You should familiarize yourself with what the different Dashboard Warning Light symbols and lights mean so that you know if it requires immediate attention. The location, design, and color of each warning light and dashboard symbol can differ among truck manufacturers, but here are explanations of what the most common symbols mean(Dashboard Warning Light).
Check Engine Light: The check engine light can be indicative of both major and minor engine issues. If your truck’s check engine light comes on, check to see if any other warning lights have come on as well, such as those showing that your diesel engine is overheating or that the oil pressure is low. Pull over when it is safe so that you can turn your engine off as soon as possible.
Alternator Check Light: If your alternator check light comes on, this could be informing you that your truck’s alternator is not correctly charging your battery. When this happens, you should pull your heavy duty truck over when it is safe and only use the necessary battery-operated accessories, such as your windshield wipers, headlights, etc., until you can get the alternator checked by a diesel mechanic.
Low Coolant Level Light: The low coolant level light tells you that your coolant levels are low. This does not need to be attended to immediately, but you should schedule truck maintenance in the near future so that a diesel mechanic can find and fix the cause of this issue.
Tire Inflation Light: If your alternator check light comes on, this could be informing you that your truck’s alternator is not correctly charging your battery. When this happens, you should pull your heavy duty truck over when it is safe and only use the necessary battery-operated accessories, such as your windshield wipers, headlights, etc., until you can get the alternator checked by a diesel mechanic.

Example-Dashboard Warning Light

There are a lot of signal lights on the Dashboard Warning Light of a truck, and it is impossible to list them all for you. The following are the five most common vehicle warning lights, hoping to draw the attention of vehicle owners to the signal lights on the dashboard.

1.Cab tilt warning light

2.Check Engine light

3.Oil Pressure Warning

4.Anti-lock braking (ABS)

5.Coolant Warning Light