2 Common Mustang Sequential Tail Lights Problems

Having issues with the tail lights on your Mustang can cause more damage than taking time and fixing it.

Of course, it is irritating, but every car trouble is. 

Several problems can make your sequential tail lights stop working, or at least partially stop working. 

But, you’ve come to the right place. Hopefully, some of this advice will give you back illumination and save you further trouble. 

In this article, you will see a few common problems that can occur with your Mustang Sequential Tail Lights and what you can do to fix them. 

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What Should I Do If My Mustang’s Sequential Lights Stop Working?

2 Common Mustang Sequential Tail Lights Problems

You might contact your manufacturer to request a replacement under guarantee for the tail lights or the harness.

But, of course, you can only do that if you are still in the right time frame and didn’t do anything that breaks the guarantee. 

Take the tail light and harness assembly apart and look for any exposed or loose wire if you don’t have a warranty or if it has expired. 

Test the wires to determine if they are defective or if everything else checks up.

Inspect the bulbs first if the lights suddenly cease functioning.

If none of that worked, keep reading for more ideas on fixing the sequential tail lights. 

What You’re Probably Experiencing 

As we said at the beginning of the article, there can be several problems. 

In the following few lines, we will number any problem we can think of and how it looks or what you might experience if you have that exact problem. 

Tail light Not Properly Illuminated

You can discover this problem when using turn signals when driving. 

Usually, when you press a turn signal, you will see the indicator light pop on, but this time it will flash rapidly; it looks something like fast clicking. 

That might indicate that you have a blown fuse, but, Mustang (at least s550) uses LED lights.

If you check the turn signal on the outside, you will find that the center column of the three columns is not illuminated. 

How to Fix It?

To try and fix this, you can disconnect the tail light for 15 minutes and then reconnect it.

That should probably resolve your issue, but, for some people, it fixed it for only a short period of time. 

If that doesn’t work, try disconnecting the car battery for half an hour, reset the body module, and try the tail lights again. 

Some Mustang cars manufactured on or before April of 2016 may have some problems with lights. 

For example, it could display an outage of the:

  1.  rear tail, 
  2. turn signal, or 
  3. stop lamps.

That is probably why you have this problem, or it simply broke down. 

Faulty or Wrong Plug ‘n Play Kit

Sometimes you try to fix the problem yourself, which ends up messing things even more.

Not that there is something wrong with fixing things yourself, but simple mistakes are always possible because of the lack of information. 

You’re probably experiencing having the outside light stop lighting up when you brake or use the turn signal. Also, it might occur when you try to lock your car with the remote. 

On the other hand, the confusing part is when you hit the unlock button on your remote key, all the lights turn on for a moment. 

How to Fix It?

There are a few things you can try. 

  1. Try and swap the bulbs a bit around. See if anything is different with the tail lights. 
  2. Try and replace the light bulb with a new one. 
  3. Clean the harness connector contacts. 
  4. Clean the bulb contacts.
  5. Take apart the tail lights that have been acting up and check if all the crimps are connected properly. There is a slight chance you didn’t connect them right when installing the kit. Also, replace the middle bulb with the outer one. 

If nothing above works, you maybe have a faulty kit.

There is a reason for plug ‘n play kits. If something is wrong, you still have the warranty. 

What Distinguishes Cut-and-Splice Sequentials From Plug-and-Play Sequentials?

Just as it sounds, there is a difference. 

The harness that comes with plug-and-play sequential light tools may be used as a straight replacement for the factory harness.

That will make the installation quick and easy. 

Simply put them in, and you’re done—no wiring, no figuring out which wire goes where.

On the other hand, hooking into the factory electrical harness is necessary for the cut-and-splice sequential tail light kits.

That will require a little more work to finish.

However, the outcome is the same for both types; it depends on which method you like.

What Else Can I Do If None Of The Above Worked?

If your LEDs light up with the parking lights or the brake lights but do not sequence or only one or two bulbs sequence, and nothing of the above works, try the test beneath. 

The first test is only for the vehicles manufactured from 1996 to 2004. 

  1. Install the factory halogen bulbs in the sequential tail light harness, either on one side or both. 
  2. If the brake lights do not work properly, move the turn signals or four-way flashes.
  3. Check if you replaced the modified turn signal flasher if they don’t sequence properly.

If the flasher has been replaced and the vehicle fails to sequence or lacks a flasher, the harness is probably faulty.

If the halogen bulbs sequence correctly but not the LED bulbs, move on to the next test.

Bend the LED tabs away from the LED by grabbing them and doing so.

The socket tabs should also be bent inwards towards one another. The tabs are flexible and should be handled carefully and slowly to avoid breaking them. 

Knives or a pair of tiny needle-nose pliers work best for this task, but use caution and ensure the keys are not in the ignition to avoid any potential shock hazards. 

Since LEDs consume much less current, a tighter and better contact is required to transmit the reduced current and enable appropriate bulb sequencing and flashing. 

This ought to fix the sequencing issue.


Hopefully, you’ve found the answer!

If not, please don’t drive without the lights; it could be dangerous.

Instead, take your car to the mechanic and let them worry about the lights.


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