So on my 2007 gt, I bought it used and it already had a set of sequentials installed. They have worked fine for over a year, but now I've noticed that on the right side, the far left of the 3 lights doesn't flash. i.e: when i use my right turn signal, only 2 of the series go off. Yet, the tail light itself is fine. I have no experience with these, where does it sound like this problem is coming from? Thanks!

 

Sounds like the sequencer board that is wired into the harness. I had the same problem with one of mine. I bought mine at WebElectric which came with a lifetime warranty. They replaced it no problem. However, since you bought your's used I don't know that there is much you can do but buy a new set. Are you sure that all the bulbs are good and seated well?

 

Have you checked the bulb? When I installed my sequentials I had 3 bulbs go out within a week. those bulbs have 2 elements in them. One for the tail light and one for the Brake/turn signals. It's possible for only one to go out so you could have all 3 tail lights working on one side but only 2 brake/turnsignal lights on that side. Bulbs are cheap. If you don't want to buy a set of bulb,s just swap that bulb with another on the same side to see if the problem moves with the bulb.

 

If the bulb is good, do this before replacing anything:

Remove the tailight so you can access the harness connectors. Disconect the connectors, spray both halves with contact cleaner and immediately wipe the contacts by plugging and unplugging a few times. You may need to repeat the spray and plug/unplug a few times. That has solved a few instances of persnickety sequentail functionality.

 

Most lights have a reset sequence, see what Webelectrics offers and duplicate it. It may work.

 

^^ This. You need a new tail light bulb if that brake light still works.

I've had this happen a couple times now with my sequentials...it's a very easy fix.