Ok, here is something challenging (for me at least):
I’m trying to figure out why my stop lights wont work. And my horn for that matter.
The image attached is a scan from the 1986 RX7 workshop manual. According to my observations and tests, there has to be something wrong with the CPU unit. I tested the fuses (60 and 20 Amp) and they are fine. I’m also sure that the switch (red color on the picture) is working fine, since when I step on the brake pedal it cancels my cruise control. This leaves me thinking it has to do something with the CPU (I put a ? mark next to it on the picture). Now there’s a drawing of the actual circuit inside the cpu and that’s the part where I am left without a clue. Do you think that the CPU causes all my lights not to work ? (of course I checked the light bulbs). When I press on the horn, it doesn’t work either. One more clue I got from the other circuit drawings : Anythin that doesn’t go thru the CPU works (like the backing up light, turn signals …).
So what do you all think? Thanks for any suggestions.

 

Sounds like you need to consider 'the cpu resolder'. I did it a few months ago when I lost my high beams, key & lights-on chime, and the alarm wouldn't arm. After a long day of resoldering every joint, testing and then re-resoldering a few definate week points, everything went back to normal.

I got my instructions from:
http://www.teamfc3s.org/faq/FAQ.html#S2

 

thanks for the link. i went to check it out and the instructions are really good. I will give it a try this weekend.

 

yes from my guess n experience with the 2nd gen rx7...the cpu should be the problem.....how do i know ? cuz i have the same problem....my horn n warning lights dont work....u should take it apart n re solder some of the circuits together.....there is a site that teaches u ...its fairly easy.....