Does your dash cluster look like this Christmas Tree?!
Whether in your personal car or in your work vehicle, you’ve probably experienced, at some time or another, a dash light coming on with an unfamiliar symbol in a bright orange or red color. What you may think next is, “What does that symbol mean and what is going on with my vehicle?!” Sometimes these illuminated lights and symbols can be as simple as a reminder to place your seatbelt on and other times they can be an advisory to “Check the Engine” or “Stop the Engine.” In some special cases when a light is illuminated it may not even affect the operation of the vehicle. Those scenarios can certainly cause some confusion.
Dash lights on vehicles were created to inform us of the condition the vehicle is operating in. Some examples could be a low pressure or fluid advisory to check certain service items or a light that indicates if specific systems, such as ABS and traction control, are turned on or off. Some dash lights are simple reminders to check the system when safe to do so and others can indicate serious concerns with the vehicle and its current mechanical condition.
At Managed Mobile we are dedicated to ensuring that your commercial truck is not only within compliance but that it is running safely and reliably. From Anti-Lock Brake and Transmission Warning lights to Check/Stop Engine lights, we are here to provide you with insight on your vehicle’s current condition and with repairs to the affected systems.
Now let’s take a look at some of the dash lights you could come across in your commercial truck. Some of the examples below are manufacturer specific or are a manufacturer’s version of a standard warning light. Most of the examples below tend to follow a standard symbol guide to keep the driver informed of what is going on with the vehicle while either parked or running down the road.
Check Engine/Service Engine Lights
This light is illuminated when there is an issue with the engine, performance of the engine, and/or associated systems such as communication wiring between the main engine computer and the other modules throughout the vehicle. From a bad sensor to an out of range measurement of engine vitals, this light should be diagnosed as soon as possible to ensure the vehicle, or other systems such as the exhaust after treatment system, does not sustain damage.
Priority Level: High
Diesel Exhaust Fluid (DEF) & Diesel Particulate Filter (DPF) / Exhaust
After Treatment Service Lights
Implemented by the California Air Resources Board (CARB) as of January 1, 2012 all CA diesel trucks newer than 1998 that are commercially operated over 26,000 GVWR are required to reduce emissions by utilizing a Particle Management Filter System. Since early 2010-11, manufacturers have been fitting their vehicles with DPF/SCR systems to control the emissions put out by their vehicles to stay complaint with ever changing Federal and State emissions laws. If you see this light illuminated, sometimes with a red “Stop Engine” light; your vehicle may be close to “derating” in which the engine ECU will limit how fast teh vehicle can travel. The first level would limit the vehicle to under 55mph. However, if the concern is not addressed, some vehicles will go into a 2nd level of derating which will limit your speed to under 25-30MPH. It is advised that if you see this light on in conjunction with a stop engine light or flashing, to have your truck’s Exhaust After Treatment System looked at for possible concerns. Some trucks may need a simple forced regen, others may have a bad sensor related to the Diesel Exhaust Fluid system, or it could be possible the vehicle is due for its DPF cleaning service.
Priority Level: High
Tire Pressure Monitoring System (TPMS)
What light is this?! Is that a horse shoe light?! My vehicle doesn’t have any horses or horse shoes last time I checked?!
This unique and newer dash light symbol to the left is a TPMS or Tire Pressure Monitoring System warning light. This light can either be illuminated as a solid light (System Fail/Need to Check) or as a flashing warning (Rapid Air Loss). If this light is on, be sure to check and adjust your tire pressures to specification. Your correct tire pressure can usually be found in the driver side door jamb.
Priority Level: Medium to High (Flashing)
Low Coolant/High Temperature Warning
If you have ever had a truck you are driving overheat or had a low coolant level while driving, you may have seen this symbol appear on your dash. Some vehicles come equipped with a coolant level sensor notifying you when your coolant level is low. On other vehicles this light may only be illuminated if the operating temperature of the engine has crept above a safe operating range. If you see this light while driving, be sure to check your engine temperature gauge and pull over when safe to do so. There may be an active leak or concern with your vehicle that may require diagnosis. Do not open pressurized caps or check the cooling system while the system is hot! The cooling system is under pressure when hot and may overflow causing a risk for burns and injury when vented.
Priority Level: High
Low Brake Lining/Low Brake Fluid Warning
Standard equipment on some imported vehicles, the brake lining warning light was designed to notify the operator when the brake linings have worn below specifications. Similar in symbol design, but notifying a different concern, the brake fluid warning light will illuminate when the brake fluid level or air pressure level is below specifications. In some vehicle designs the light is to notify you that parking brake is applied. If this light comes on, it is advised that you have your brakes and brake system checked as soon as possible.
Priority Level: High
Glow Plug System Light
Normally illuminated within the first minute of cycling the ignition upon cold start up, the Glow Plug light is to notify the vehicle operator that the glow plug system is on. In some instances, it may indicate a malfunction with the system. Glow Plugs are used to ensure that close to optimum combustion occurs when the engine is started for the first time or from a cold state. Without glow plugs, or with a malfunctioning system, a vehicle can experience hard starting, rough idle, or even white smoke exiting the exhaust until the engine is brought to operating temperature.
Priority Level: Low to Medium
Antilock Brake System/Traction Control/Electronic Stability Control Systems
First introduced into cars and vehicles in the early 70’s, Anti-Lock Brakes (ABS) & Traction Control Systems (TCS) were designed to assist braking and controlling vehicles under low traction or hard braking conditions. When your tires lose contact or traction with the road braking and steering can become dangerous and sometimes even unpredictable. With the help of ABS and TCS the vehicle will recognize a wheel traction or stability loss via the sensors monitoring data and will pulsate the brake pressure being applied by the driver to allow the sliding wheel to regain traction with the driving surface. If this light is flashing during brake application the ABS system is being activated and you may feel a small pulse in the pedal. This is the vehicle’s braking system being applied and unapplied to help regain traction. If a vehicle is equipped with traction control, there may be a loss of power from the engine and possible downshifting from the transmission in an attempt to get the vehicle back into the control of the driver. However, if these lights are illuminated at a stop or driving, there may be a concern with the ABS/TCS system or the light is notifying the operator that the ABS/TCS is disengaged. If you have not turned off your ABS system and this light is illuminated, you may want to get your brake system inspected before you have a driving situation where ABS can assist in keeping control of the vehicle.
Priority Level: Medium
Oil Pressure Warning Light
If you see this light, stop your vehicle as soon as it is safe to do so!!! This warning light indicates that there is a low oil pressure concern that could be due to low oil or a problem with the vehicles oil pump, oil passages, or sensor. If your oil level is good, further diagnosis of the engine’s oil system is required.
Priority Level: High
Transmission Warning/Malfunction Light
Why is there a thermometer with a gear symbol around it on my dash?! This light is to notify the driver that the transmission may have detected a fault with its operation. Sometimes the fault or slip in shifting can be so minute that you don’t even feel it occurring. With modern ECU’s and Powertrain Control Modules faults are detected and recorded within milliseconds. Note: On some make and models this light is also used a filter service reminder light and may require specialty scan tool software to diagnose and reset the maintenance interval.
Priority Level: Medium to High (Flashing)
Light Bulb/Lamp Malfunction Caution Light
This handy little light is a simple notification that one or more light bulbs on the vehicle’s exterior (brake, signaling, marker) have a fault or have burnt out and require replacement. Check your exterior lights to see if they are all functioning correctly and have not burnt out.
Priority Level: Medium to High (Brake Lights-Safety Concern)
Fuel Contamination/Water in Fuel Warning Light
How could I need gas?! My gauge is reading above empty?! When contaminates such as water, dirt, or foreign liquids such as coolant enter the fuel system, this light may be triggered by its sensor to inform you that your fuel filter is in need of replacement. Also further diagnosis of the fuel system may be required. In some cases, coolant or other liquids may be entering your fuel system potentially causing damage to the system (injectors, pump, lines) and eventually going into your engine. Contact MMI to schedule a repair technician to inspect your fuel system to ensure further damage is not made to vital components that keep your vehicle running well.
Priority Level: High