1990 Miata Engine and Chassis Harness Separation Help.
 

So guys, I need help separating the two and removing the engine harness. I have the factory wiring harness, but it seems as if a lot of things are tied together. Hell, I only need the lights to work. Everything else can GTFO. Can anyone give me some links to help me or offer any advice? I'm starting to get stumped. And if you are wondering why I am doing this, there is another power plant going in it.

I found this diagram and the only thing questionable was the brake light, and that raises throttle, so it can be ditched. I guess what I am asking is can I simply trace all of these wires and get rid of them?

Bump?

You'd be better off building a new body harness scratch, trying to separate the two is a major pain in the ass. If all you plan on keeping is the lights just make a new one, less wires, less cutting and soldering, not twenty years of road grime and sticky electrical tape.

Is there a tutorial anywhere? I found out the NA cars have a complex box for turn signals. It would be nice to at least reuse the fuse box, relays, and flasher unit to cut costs.

I recently did this on my 91. Mainly to scratch build a MS3X harness and get rid of the mound of wiring that isn't needed. I ended up using my own fuse box and tucking and Mil-spec'ing the entire harness in the process. Basically I just studied the wiring diagram and cut out what wasn't need then cut/extended/spliced as needed. I will tell you now it is easier to just cut all the grounds out in the beginning and rerun them when you are done. They are so intertwined in the harness it is impossible to sort it all out.

Probably not, given that jobs of this nature tend to each be unique.

The best tool is simply a copy of the wiring diagrams from the factory service manual, and some patience. Here is the manual:

http://boostedmiata.com/servicemanua...vicemanual.pdf

Right-click, Save As.

As you will find, there is very little segregation of the various harnesses by function. The several harnesses join one another at the "Common Connectors", which are the ones denoted by an X, and are described in pages 1178-1180.

Here is a link to where you can find just the wiring diagrams.

Yeah guys, I have the diagrams and I am growing tired of this stuff. I ordered a universal chassis harness from keepitclean.com.