69 THUNDERBIRD turn signal

Hopfully someone out there can answer my question, my turn signals are sequential, and it dosnt work right. the turn signals only the inner lights come on, and same as on brakes. now i disconnected the sequeintial box and they do the same thing. i dont think that there is anything wrong with the electrical because they work at all. now i was thinking that it could be a ground or the sequential box. i am running out of ideas and hope. there is also a third brake light that i was thinking might be part of the problem so i was going to disconnect that. the sequential box is fried because it looks like rats or something pee'd on it and well its no good. so that is bad with no questions. so we will be getting a new one here in not too long, but if there is anyone out there that has a problem like this, PLEASE HELP. also if anyone knows where i can find a wiring diagram i would like to see one. thanks for any and all help.

To troubleshoot go here: http://www.thuntek.net/cougars_unlimited/69seqts.htm
This is the home page:
http://www.thuntek.net/cougars_unlimited/default.htm
Do a Google search for 1969 Thunderbird shop manual to find places to buy manuals.