Hi im Matt, I have a 1987 RX7 all stock non turbo. Im trying to put a universal ignition in but it is onlya four post, battery , Iignition 1, acc, and starter. The factory switch is five wires, differece is it has ignition 2. Im trying to the factory plugs so im not choping up a good wiring harness. Should i have another switch? My question is how do I wire this so it works properly?

 

Looking at the stock plugs there is a plug which features a Black wire and a wire that is Black/White. The Black wire is from the main fuse (battery) while the other wire powers the IG1 fuses (these are fuses used to start the car only). Another plug also has two wires where one is Blue and the other wire is Black/Red. The Blue wire is for ACC while the other wire, B/R, is for IG2 which is for fuses that are not directly used to start the car such as wipers etc. There is then a plug with just one Black/Red wire and it is used for the starting circuit (starter). You'll then in your case have to decide if you want to combine IG1 and IG2 together. The reason why they are differentiated is because it takes a fair amount of the battery power to start the car thus fuses to power accessories not needed to start the car are left for IG2. Now if you had the fuses powered by IG2 in the off position such as rear wiper, wipers, cooling fan and sun roof then they won't bring down the voltage and the voltage present could be used to start the car. Of course one would say these items aren't in operation when starting the car which is true so by combining IG1 and IG2 on one terminal it should not cause any problems.