When you hear another enthusiasts talking about sequential lighting, they are talking about their tail lights. Sequential tail lights function by illuminating a single bar at a time on your Mustang’s distinctive and iconic tri-bar tails until all three are light up, at which point the pattern goes blank and then repeats from the beginning.

2011 Mustangs have sequential turn signals and from the factory and 1999 Mustang are able to add it. Even though you may already have a Mustang that offers some stock sequential lighting, you modify it to add that functionality to more modes.

Sequential tail light plug-and-play harnesses add sequential functionality to your:

•    Hazard lights
•    Brake lights (cycles through once before staying fully lit)
•    Lock and unlock modes

Sequential tail light harnesses plug right into the stock wiring harness and connect seamlessly to your tail lights, taking up barely any room at all. The harness takes the existing functionality and using safe and durable wiring to extend that same functionality to any time the tail lights are activated.

Sequential Mustang tail light harnesses are relatively simple to install and can be knocked out in about an hour. All you need are screwdriver and wrench to remove the tail lights to be able to plug in the harness.

Harnesses are relatively cheap to pick up and can be had for right around $60. When picking one out, make sure you are going with a reliable manufacturer who you can trust and that they are backed up by a warranty.

The difference is just what it sounds like. Plug- and-play sequential tail light kits include a harness that will be a direct plug- in replacement for the stock harness, making for a very simple and stress free installation. No wiring, no figuring out what goes where; just plug them in and there you have it.

The cut-and-splice sequential tail light kits on the other hand do require some wiring into the factory wiring harness and will take a bit more effort to complete. Both types have the same end result however; it’s just a matter of how you’d rather get there.

If you are also looking to change up the look of your rear end while also upgrading the functionality, than you can get a set of aftermarket Mustang tail lights that have sequential lighting built into them already. In addition to adding sequential lighting to your ‘Stang, you can also go for a set of smoked tail lights or even another design altogether. Swapping out your stock tail lights for an aftermarket set is easy and can be knocked out in about an hour with a few basic tools.

Sequential Mustang tail lights are fully DOT compliant and will not get you in trouble with the police. As long as the tail lights are red and do not strobe and function as intended, then you are all legal in the eyes of the law.

Unfortunately, you cannot. LED bulbs use a lower current than the stock incandescent bulbs. To compensate for this, resistors or load equalizers are used to absorb the extra current not being used up by the LED bulbs. Within the LED replacement tail light housing, the wiring is set up as such.

The combination of said LED Tail Light wiring and the resistor from the sequential harness would will generate an excess of heat and will result in damage to the wiring and connectors. Therefore, you should opt to install standard tail lights and combine those with a sequential harness, since they can be used with LED bulbs as mentioned above.

Absolutely! The LED brake light bulbs have the same connector as the standard incandescent bulbs. Therefore, you can simply remove the stock bulb from your tail light harness and replace them it with the super bright red LED bulbs. These bulbs will improve your braking visibility for both drivers behind you, and as well as offering additional light output while in reverse.

Along with the LED bulbs, you will also need to splice in (2) resistors on both the driver and passenger sides of your tail light wiring in order to absorb the extra current and allow the lights to function properly. Without the resistors being installed, your lights will sequence or blink at a rapid pace and will not be giving you the look you were after.

Have a sweet spot for the new 2013 style tail lights? AmericanMuscle now offers a great set of tail lights that offers everything you could want. The Raxiom Gen5 tail lights are fully equipped with LED bulbs throughout, a sequential harness built right in and, best of all, they are a direct replacement for your current tail lights.

No wiring required, no modification necessary, nothing extra needed; simply bolt on, plug-in and enjoy! These tail lights will transform the rear of your Pony and will have onlookers wondering what year your Mustang is and how you got them.

Depending upon your manufacturer, you may have a warranty for the tail lights or the harness and you can call them to replace it (if you are still in the valid time frame). If you do not have a warranty or they are no longer covered by one, take the tail light and/or harness assembly apart and check for any loose or exposed wiring. If that checks outs, try testing the wires to see if they are faulty. If the lights stop working altogether, check the bulbs first.

Before replacing your LEDs or pieces of your harness, consider these steps.

When to perform this test: if your LEDs light up with the parking lights, or with the brake lights, but will not sequence or only one or two bulbs sequence.

Test #1 (1996-2004 ONLY) -  Install the sequential tail light harness on one or both sides, and in the harness install the factory halogen bulbs. Then move the turn signal or 4-way flashers to see if the brake lights with the harness are sequencing properly. If they do not sequence properly check to make sure you swapped out the modified turn signal flasher.

IF the flasher has been changed and it still does not sequence or does not have the flasher (2005 and Newer) then the harness is defective. 

IF it does sequence properly with the halogen bulbs, but not with the LED bulbs proceed to the second test.

Test #2 - take the tabs on the LEDs and bend them out away from the LED. Also, take the tabs on the sockets and bend them in towards each other. This should be done gently and very slowly, because the tabs are very flexible and easy to break. The best tool for this is a knife or a set of small needle nose pliers, but be careful and make sure the keys are NOT in the ignition to prevent any shocking hazard. Because the LEDs draw much less current, it needs a much tighter and better contact to transfer the lower current to allow the bulbs sequence and flash properly. This should solve the sequencing problem.

IF this does not fix the problem, replace your bulbs.

• Plug and play connectors are a less permanent and simplier version of cut and splice kits
• You can not use replacement LED tail lights when using a sequential tail light harness
• You can however use LED brake light bulbs when equppied with a sequential harness
• Gen5 tail lights keep your S197 in the modern loop

Hopefully this article has helped answer some questions that you may have had about what you can and can’t combine when it comes to LEDs and sequentials. With a ton of options and combo kits available on AmericanMuscle.com, there’s sure to be a kit that will offer you the function and look you desire. The sequentials really are an eye-catching mod that will leave you wishing you could see them while driving. Adding some touches on the front end will also get you noticed even further. If you wish to make your light output even brighter, grab the Raxiom reverse light LED conversion kit for the ultimate upgrade.