It is a long held belief that any lights that are installed on a commercial motor vehicle, particularly truck manufacturer installed lights, must be capable of operation, day or night.  More often than not, old school drivers know this to be true, the young drivers they are training are taught this to be true and many mechanics believe this to be the law, including those who are inspectors performing the DOT required annual Periodic Inspection.  Indeed, many law enforcement officers will issue a citation for any light on a CMV that is not operable.

*Image courtesy of Freightliner truck driver Nick Neeley

The real truth lies within the federal regulation located at Title 49, Part 393, Subpart B.  All of the required lamps for each class of CMV are located in Table 1 of §393.11.  Any lamp not shown in Table 1 is, therefore, not required.  This would include fog lights, running lights, chicken lights, decorative or other accessory lighting.
Paragraph 393.9(a) states:  “All lamps required by this subpart shall be capable of being operated at all times.  This paragraph shall not be construed to require that any auxiliary or additional lamp be capable of operating at all times.”  This regulation is one of the rare regulations that not only state a requirement, it tells us what lights are not required.

Why is this information important?  Mechanics certified to perform Periodic Inspections have been known to fail the inspection because of an inoperative non-required lamp.  Of course you could receive a pass after the shop charges the driver an obscene amount to replace a burned-out lamp.  Worse yet, an ill-informed law enforcement officer might cite you for an inoperative fog light during a level I roadside inspection.  This would not only result in a fine, the logging driver would receive 2 CSA points on the driver’s score and the carrier would get the 2 CSA points applied to the carrier rating.  The fine may stick but now that you know that the inoperative fog light does not violate a federal regulation, you may challenge the CSA points using the DataQ process at

My comments aren’t to suggest that a driver should not worry about an inoperative lamp.  Any obvious defect, violation or not, is a conspicuous invitation for a diesel cop to inspect the truck for other defects that could lead to an out of service order.
The above comments refer to federal regulations only.  Some states may require any or all accessory lights to be operable; this would be covered under the FMCSA regulation at paragraph 392.2 which requires a CMV operator to comply with regulations of the jurisdiction in which the CMV is operated.

*This article was submitted to us by a Team Run Smart member in the Truck Forum. Do you have an article that you would like to submit for consideration to be published on Team Run Smart? Email with your article or suggestions for future content. And make sure to come back to the  Forums on Team Run Smart to stay ahead of the trends and in on the conversations to help run your business smarter. 


Comments (20)

Terry OConnell

After a 30 year U.S. Coast Guard career, Terry and his wife René, obtained their CDLs and began a 19 year adventure in expediting. In 2008, he entered his third career working for the Safety Department of an interstate carrier.

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Look into tin coated marine wire.

November 13, 2012 7:12:19 AM

Rick, dielectric grease on the connections helps a lot.

November 12, 2012 15:38:28 PM

After hearing Terry's "chicken lights" explanation a few times I feel a lot better prepared to deal with an inspector than I was before.

I have removed any ancillary lights that were not part of the original equipment that came with the truck. I did this for fewer headaches (when discussing them with an uninformed inspector) and cost savings as well. I take pride in the way my truck looks so it would drive me crazy if a light burned out.

Now if I could just figure out a way to combat the constant rotting out of the connections caused by the mag-chloride they out on the roads in winter ............

November 12, 2012 15:34:47 PM

Decorative lights?!....There is no evidence that extra lights make you safer. What a waste of time and money. Money better spent on family and/or home or even food in your stomach.

October 04, 2012 11:35:42 AM

I don't know how many times I've heard, "If it's on there it has to work." So, naturally you start believing it because you hear that all the time. Thanks for a great article and the sources to back it up! Also, great to see a fellow veteran Coastie in the trucking world.

October 04, 2012 6:59:16 AM

Chris. I, for one, applaud your light maintenance ethic and I surely agree that the appearance of a well maintained truck will go a long way at an inspection site. With regards to your comment about the South Dakota law that may prohibit clear lenses on a red tail light, I would invite your attention to Federal Motor Vehicle Standard 108 (FMVSS 108) which says that clear tail lamps are not allowed.

Your comment leads me to another area of concern. At what point is a 12 diode light fixture deemed defective? Contained in the Federal Standards is the requirement that a given light must be visible for a given distance during normal light incidence. We doubt that any LEOs carry light meters to determine the adequacy of a lamp so common sense prevails here. I have asked FMCSA senior officials, States of Missouri, Kentucky and Ohio CMV officials and two manufacturers of LED lamps for CMVs the above question. The answers I received have been less than encouraging. In the worst case, one highway patrolman told me that if one diode is inoperative, the light is defective; another trooper said if he can see the light at a reasonable distance, it’s a good lamp regardless of the number bad diodes. My observations of LED taillights have shown that a twelve diode taillight is very adequate with six failed diodes. I think a good thumb rule is to not let more than half of the diodes fail before you replace the fixture.

September 21, 2012 5:33:14 AM

South Dakota supposedly has an odd law, I've hear they cite CMV's for having the LED lights that are clear when off, amber or red when on. The DOT there says that lights must be amber or red even when off. As far as light maintenance and keeping them going, LED lights hardly ever go bad, and it really depends on the driver I guess. I clean mine before winter, wire them back together with a little dielectric grease. Also, instead of just patching the wire here and there, replace the whole wire every couple of years, its a lot cheaper that way. Also, dispelling the idea that lights draw attention of DOT somehow, I have plenty of lights ,they all work when I roll across the scale. I believe many officers will look at a truck and say anyone who keeps 40-60 lights all running properly is probably taking care of the rest of the rig too. But then again, how many truckers are like me spending their weekends under the rig greasing and checking stuff??

September 20, 2012 20:23:45 PM

Regulated lights and a few "chicken lights" or decorative lights to show lane markings while driving out in the "Boonies" of Northern Ontario on a dark night are more than sufficant. These rigs that glow in the dark are great to look at but are all those lights really needed, and any unwanted attention is also not needed.

September 20, 2012 11:11:48 AM

Yeah, my opinion is leave the extra lights to the show trucks. Seems like an extra cost and extra worry to those trying to maximize profit.

September 20, 2012 10:09:57 AM

Good to know. I agree that even if the csa can't cite you with a faulty lamp it is asking for a roadside inspection.

September 20, 2012 1:10:34 AM

Going a little of track but the Over Size vehicles that continue to display the oversize banner after they are unloaded does not seem right. Makes me think of us and after we unload a hazmat load leaving the hazmat placards displayed on the truck.

September 19, 2012 5:55:56 AM

Henry, So long as the State law doesn't preclude you from complying with the Federal law or regulation, the States can certainly enact their own laws. one place this is discussed is in 390.9.

I can't imagine anyone disapproving of a volunteer fire fighter or other government authorized official from displaying flashing red, blue or amber lights when on duty and required. On the other hand, I don't understand the proliferation of tow trucks with a tow displaying flashing red and/or blue lights while speeding along the hammer lane. After leaving the scene, they are no more engaged in an emergency than any other combination vehicle.

September 19, 2012 5:37:58 AM

Can states have their own rules pertaining to proper and legal lighting which differs from federal rules? One example I can think of is in the state of Pennslyvania, the volunteer fire deparment personnel use flashing blue lights on their personal vehicles to repsond to emergencys. This same flashing blue light would get you in a great deal of trouble in most other states.

September 18, 2012 22:42:05 PM

I have tried to challange many of the violations that are either incorrectly written, such as the wrong code, or do not apply at all to our operation. It seems that as long as the State that writes the violation, and are also the ones who process the Data Q's we are fighting a loosing battle. I have prevailed on very few of the violations, but I always try to challange them if they are incorrect. I have been told at the Mid America Truck Show, that this practice is about to change as the FMCSA will be forming a committee to look at the Data Q's and determine if the violation is correct or not. Especially if you have proven in a court of law that the vioplation was incorrect, and the charge is dismissed. Does anyone have any further information about this?

September 18, 2012 9:26:36 AM

Terry, thanks for the comment. I will implement that with our Safety Team

September 17, 2012 23:11:21 PM

The rules are one thing and time at the roadside explaining the rules is another thing all together. I choose to not have the extra lights to avoid the chance of having a unsheduled meeting with the DOT at the roadside.

September 17, 2012 10:17:53 AM

When our sleeper was built there was a panel of lights running along the bottom of the sleeper and we had them take the panel off and replace with a plain panel with no lights. There is enough on our truck to make it stand out with out having the lights to cause a potential problem.

Interesting article Terry and I hope you share more of you articles in the future.

September 17, 2012 4:42:40 AM

Great article Terry, all those decorative light are impressive out on the highway at night but the first thing that comes to my mind is more maintenance cost to keep them operable and increase draw on the batteries resulting in shorter life for the alternator. They are pretty though. And one or two lights out will grab the attention of law enforcement officers.

September 16, 2012 21:50:39 PM

Thanks for the comment. Drivers and carriers faced with an inappropriate entry on a roadside inspection form might consider calling the officer that conducted the inspection. You just might find one that is willing to discuss the matter before you submit the DataQ. At least the officer will have a heads-up that it's coming and might not be defensive when his superiors send it down to him for a response.

September 16, 2012 20:30:01 PM

What is legal and what the new breed of Motor Carrier Enforcement writeds up is as different as day and night....with the CSA there are a lot of things going on reports that cost carriers points that are not correct. ANd while Data Q is supposed to resolve those the current admistration is not helping carriers with removing poor write ups. Our company Gully Transportation has a blue company ID light on its trailers. Prior to ever putting the light on inquiry was made thru FMSCA all the way up to Washington. Gully is correct that the light is legal but continues to fight the battle. I suggest those with decorative lights (sounds better than chicken lights) carry this with them. Thanks for the info on this as well. It is a good write up and in a approiate time.

September 16, 2012 17:13:37 PM