HOME MADE SEQUENTIAL TURN SIGNALS
Written by Rusty
This procedure will work on just about any of the 1994-1999 Mustangs. Some of the wiring colors may be different as this applies to the 1999 Mustang.
Background: Since the introduction of the 1965 Ford Thunderbird, I have always loved the look of the sequential turn signals. Every car I’ve owned since 1982 has had sequential turn signals.
For those of you who don’t know what sequential turn signals are, it consists of 6 lamps, 3 per side which flash one by one from the inboard (near the license plate) to the outside. This makes for a rather unique appearance when one taps on the brakes, or is making a left or right turn. When Ford redesigned the Mustang for 1994, I was a bit disappointed that they choise to go with horizonal rather than vertical lamps, but with modifications, I had my sequntials up and running, although they didn’t really look that good. With the return of the vertical lamps in 1997, I ordered a set of vertical lamps and installed them into my 1995 which made them look MUCH better. I traded off my 1995 Mustang in March of 99 and picked up a new laser red stang. The was about 1 week old when I got the itch to install the sequentials.
Installation: You will need to remove the inner liner inside the trunk to access the tail lamps, as ford, probably for soundproofing reasons, isolated the tail lights from the rest of the car. There are two plastic “nuts” per side which need to be removed to allow you to reach inside and remove the four brass colored nuts per side. Each nut has a rubbery substance applied to the edge of the nut, probaby for sound/water proofing. After the four nuts are removed, disconnet the black electrical connector, then pull the lamp assembly loose, and work the rubber grommet out of the car.
Lay the lamp assembly on something soft so you don’t scratch the lenses and mark the lamps as noted in the pictues. This will be explained later. Twist each lamp from it’s socket, and pop the wire harness stays out which will free the harness from the tail lights.
Cut the lamp marked with the X on it, and pull the lamp out. This lamp is the correct 3157 lamp, but ford decided to use only the parking lamp side of this lamp. (At least with the 1999, if not, purchase 2 extra 3157 bulbs). Make sure you leave some extra wire for splicing when you cut this lamp out. Ford, for a long time has used pretty much the same wire color combonations on it’s lamp harnesses. The lamp socket marked 1 will require no modifications, but for lamp 2, cut the wire colored green with an orange stripe. This is the “hot” wire element which lights the brake/turn signals. Leave enough extra wire for both sides so you can do some splicing. I used quick disconnect connectors for this project. Just in case the electrical flasher stops working, all you will have to do is just connect the connectors back together until you order a new one, or trade your car back in.
Instructions are included for the sequencier. Connect the white wire from the sequencier to the cut green/orange wire in the HARNESS which was disconnected from lamp #2. The white wire provides the power to the other two lamps. Connect the yellow wire on the dynamite stick to the cut green/orange wire of lamp #2. Connect the red wire on the dynamite stick to the BRAKE/TURN wire of your NEW 3157 lamp socket. Connect the BROWN wire of the lamp harness to the PARKING lamp wire of the NEW 3157 lamp socket. The brown wire provides the power for the parking lamp. Now connect the blue wire of the dynamite stick, ground wire of the NEW 3157 lamp socket to the remaining BLACK wire of the lamp harness bundle. This is the ground wire for the lamp socket as well as the ground for the sequencier. Once this is done, your completed wire harness should look something like this when assembled back into the tail lights. Lamp marked #1 should be inboard, with #2 next to it, and the new 3157 socket on the outside. Note the position of the dynamite stick. This is a tight fit and will not require it to be glued, taped etc.
Reinstall the wire harness connector back through the hole, and resecure the rubber grommet. Remount the tail light assembly and reattach the 4 brass colored nuts. Reconnect the lamp harness to the plug. Before replacing the inner liner, turn on your emergency flashers and make sure all lights light in sequence, from inside to outside. The procedure for the right side tail lamps is the same, EXCEPT for the wire colors. On the right side, the brake/turn wire colors are orange/green. All other wire colors, including the sequencier are the same.
After both sides are done, turn on your emergency flashers to verify that all lamps light in sequence. Turn off your emergency flashers and turn on your parking lights and make sure all 6 lamps work. Reinstall all the inner liners and your finished!
Well, almost............... I’ve had 2 or 3 sets of dynamite sticks, and I guess do to the manufacturing process, some flash quicker than others. If yours has a “delay” between each bulb lighting, you will need to modify the “blinker box” which controls the flash rate. In the old days, this was done by popping out the round silver flasher, poppping off the cover and spreading the contacts to make it flash at a slower rate. Well, this is the computer age, and Ford has an electronic flasher.
I won’t get into the details of the circuit, but anyone with an electronic background will discover that it’s a simple “555” timer circuit which fires a relay. What you will need to do is remove the flasher assembly. On my 1995 Mustang, it was located above the brake pedel. On the 1999 Mustang, it’s located to the left of the radio. (see picture) It’s easy to spot. It’s BRIGHT yellow. You will have to do some work though, it’s mounted using Fords REALLY hard to remove electrical connectors. Once removed, it’s a sealed unit, but if you have access to a dremel tool or something similar, just cut the case off. BE CAREFUL not to damage anything under the cover!!!! Once removed, if you have any background in electronics, you will clearly spot whats inside the cover. Cut the timing RC resistor out and replace it with a different value. It was almost 2 years ago that I modified mine, so the value of the resistor escapes me. You could replace it with a variable resistor if you would like. I did this as a temporary measure. Once the resistor is replaced, remount the flasher, turn on your emergency flashers and adjust it so the rate is slow enough for all 3 lamps on each side to light up. Once done, that’s it! Like I said, if you get a “dynamite” stick sequencier that is fast enough, you may not need to make the modification to the yellow “blinker box”.
Now take your mustang out for a spin, and when your at a traffic light waiting to make a turn, look in the rear view mirror and see how many people point at the back of your car and smile.
For questions about this how-to you can write Rusty at firstname.lastname@example.org