Sequential Turn Signals

For All 1983-88 Cougars / Thunderbirds

Page Revised: 10 May 2019


Sequential Turn Signals

Article by
Eric Dess

The 1967-73 Cougar (or a 1964-73 Thunderbird) had one of the coolest and most unique features: the sequential taillamps, where the turn signals flash in sequence in the taillights. At the time it was called "gimmicky" but now this cool mod is enjoying a comeback. In fact, Ford brought back the feature for the 2010-up Mustang. The best thing is that it's part of the Cougar's history—you need not feel like it's a passing fad; it's here to stay. Now until a few years ago, you either had to try and splice in a system from the original Cougar (VERY problematic, and difficult to do), or try to find someone who could build a solid-state control box with Radio Shack parts. Well, thanks to newer companies, you can simply buy the pre-built kit and install it yourself in just a few hours.

We are not aware of any "plug-and-play" kits for our cars, so that means you'll need a universal-style kit to retrofit your car. Below is a list of known, quality vendors that sell sequential kits:

  • Cougars Unlimited has created one of the first mass-produced, modern era kits. This is the kit we used because it was the best available at the time. Please check their website for current price information.
  • Web Electric Products sells a universal, low-cost sequential kit that is popular with hot rodders and car enthusiasts of all kinds.


There are a few things you need to know before you buy the kit and begin installation. The kit you purchase will need to work with any vehicle that has 3 brake light/turn signal combo bulbs per side (except those specifically designated as a 2-bulb system). All 1983-88 Cougars and most Thunderbirds have 3 bulbs per side, but one of the bulbs is for marker lights only, not for brake lamps. Which leads to the next point: there is some rewiring and modification to the taillamp wiring harness in order for the 3-light sequencer kit to work. We've figured out a way to significantly reduce the need to hack up your stock harness, and those pointers will be made below.

What comes in the kit?
The kit consists of a control box, wiring harnesses, mounting screws, a new heavy duty flasher, and instructions.

How does the kit work?
In a nutshell, the control box acts as a central brain or junction box for the brake signals and turn signals that go to the rear taillights. With this system the box controls everything automatically; this is why you need to do the rewiring. Also, you will replace the stock flasher with the special heavy duty unit supplied by the kit.

What do I need to start?
Basic hand tools (wiring strippers, screwdrivers, sockets), electrical tape, butt splice connectors, and 6 additional taillight bulb sockets (if bypassing the stock harness). A test light is also very handy to use here.

The following photos are a step-by-step tour of installing the Cougars Unlimited sequential turn signal system. It may or may not be similar to other kits. This section is only meant as a supplement to the instructions that come with the kit. You assume responsibility for any actions herein.

NOTE: All photos are taken from a 1986 Cougar. Your car's setup may vary from the car shown.


Sequential Turn Signal Installation

Remove the trunk liner (if applicable). This is the stock wiring harness, driver's side, for a 1985-86 Cougars. Sockets from left to right: backup lamp, lights-on marker (inner), turn signal/brake lamp (middle), turn signal/brake lamp (outer). Your bulb order may vary, but you do have the same kind of sockets regardless.

Sequential Turn Signal Installation

This is the stock wiring harness, passenger's side, for 1985-86 Cougars. Sockets from left to right: turn signal/brake lamp (outer), turn signal/brake lamp (middle), lights-on marker (inner), backup lamp.

Sequential Turn Signal Installation

This is the Cougars Unlimited kit: both wiring harnesses, signal box and flasher. You should mount the box somewhere out of the way where no wiring will rub against metal, and also where it will be protected from water.

Sequential Turn Signal Installation

This box was mounted behind the driver's side trunk liner panel, on top of the wheel well. Since most of the stock taillamp wiring is on this side, it's a logical choice and out of the way of objects in the trunk. The box is being held down by simple zip ties. It's okay to make a custom mount for the box, if you wish. All wiring was tucked into wiring loom after the install.

Sequential Turn Signal Installation

In order for the kit to work, you need 3 brake lamp/turn signal sockets on each side of the car. For 1983-84 Cougars, you have to convert the outer marker lamp over. For 1985-88 Cougars/T-Birds, you have to convert the inner marker lamp over (next to the backup lamp). The hole above can easily be cut with a Dremel tool or sharp knife. The trick is to get the hole to look like the hole next to it...

Sequential Turn Signal Installation

...just like this one, so obviously you have to make the other hole bigger. Neatness does count for the most part, although it's possible to be a little off. So long as the bulb socket goes in, turns, and locks, you are good to go.

Sequential Turn Signal Installation

This is step 1 for the taillight socket hole. It's simply rounded out with a Dremel tool and sanding disk.

Sequential Turn Signal Installation

After cutting up the rest with a utility knife, this is what the hole more or less will look like. Make sure to double check the bulb so that it doesn't pop out accidentally. If you do take too much out, you'll have to fill the area with JB Weld and try again.

Sequential Turn Signal Installation

Instead of hacking up the stock taillight harness for the wires, you have a better option: buying new Ford taillamp sockets, as shown here, and splicing them into the wiring for the control box instead. You'll need 6 total, 3 for each side, and it doesn't matter if the sockets are for the 1157 or 2458 bulbs—your call there. This way you can preserve your stock wiring harness in case you ever need it again. You will still need to use the stock wiring harness for the backup lamps (and side markers on 1987-88 cars); the other sockets will simply need the bulbs removed. There is enough room at the bottom of the trunk well and behind the taillight panel cover of the trunk liner to let the wiring just hang.


1) Disconnect the battery before attempting to install this kit.

2) When connecting wires, use butt splices or solder all connections. The principle behind this box is that it bypasses the stock wiring for the turn signals and brake lamps. In other words, all faith is put into this box. Therefore all wiring MUST be secure and permanent or else you run the risk of losing your brake lamps and/or turn signals as you drive. And make sure that no wiring will get in the way of moving parts (i.e. brake pedal).

3) There are two wiring harnesses associated with the box: one is for power input, the other is for power output. The input harness is where you should start first. For that, you will need to get a pure brake signal, and a pure turn signal for both left and right signals. NO CHEATING HERE. If you own a 1986-up vehicle, the brake signal can come directly from the third brake lamp in the rear window. For all pre-1986 cars, you MUST run a wire all the way up to the brake switch on top of the brake pedal (green wire), as there is no other place in the car to get this signal.

4) For the turn signals, all cars must get the signals from the switches on the steering column. You don't have to strip the wires on the column or for the brake lamp; you can use a simple Scotch-Lok connector to piggyback those wires. Wiring may vary from car to car so you'll have to get the signal yourself. To get the signals you will need a test light. Remove the steering column cover. Temporarily connect the car's battery and carefully turn the key forward, but do not start the car. Put the driver's side turn signal on, and test the wires in the turn signal harness on the column. You should find that one wire flashes the test light—that's the wire you will need to hook up to the box. Repeat the same for the passenger side signal, then disconnect the battery again. Piggyback the wires and run them to the box. It's easiest to run the wires underneath the carpeting along the driver's side of the car.

5) Once all the input signals are taken care of on the box, go to the other harness for the lamps. Each socket will have 3 wires going to it: one for the brake/turn signal, one for the lamps on, and one for the ground. It's helpful to chain all the grounds together, then to one master ground (either a ground wire or bolted to metal). You will also need to chain all the lights-on wires, tapping power from one such wire from the main taillight harness. Take your time and follow the instructions carefully. Once you have all the output wires situated, plug both harnesses into the box.

6) Before you reconnect the battery, you must change the flasher under the dash to the new heavy duty unit. This is because you've added more sockets to share the signals. If you were to use the stock flasher, the sequencer would work too fast and you'd lose the effect. The provided heavy duty flasher slows down the signal to the box and lets it sequence perfectly. After changing the flasher, reconnect the battery—it's time to test the turn signals and brakes. A helping hand is good here.

7) Hopefully you'll get the sequence in the first shot. If not, you'll be checking the wiring extensively. Be patient! Once you're working fine, double check all of your connections, then properly secure all wiring away from metal and out of the way.