so im digging through the mess that is my factory wiring harness and will be running a haltec (maybe) with this build. i think i remember a write up (possibly by hypertec) about this but cant find it.

emissions are gone and this will be a bridged n/a build.

what do i ultimately need to keep out of the factory harness?

necessary lighting
wiper controls
fuse panel?
trans connections
brake master fluid level?

am i missing any more?

 

Just leave the body harness alone. You could go nuts and take out things like the adjustable suspension harness (on every car regardless if it had it), fuel resistor wiring, diagnostic connectors, AC/PS wiring. It is a lot of work. But if you have OCD and time it is doable.

 

maybe ill give it a 2nd look over this afternoon. its defiantly something i wouldnt mind doing... after all... my car has been off the street for something like 3 years. i really dont think a couple more months/years would hurt anything.

 

Having just made a EM harness for my car. It is allot of work.
As I removed the harness I labeled the stuff that I had plugged in and then started cutting out the rest. From there I made pig tails out of the factory connectors I couldn't replace. soldered in The lengths of wire I needed then used the oem ecu connectors. Sounds easy enough.but it's no easy task deff worth it tho

 

While the Mazda harness is in fact loaded with unnecessary features (every option is able to be plugged in, whether you actually have it or not), that's not the biggest problem.
After all, it's only a few extra ounces of wire and the attendant mess of unplugged connectors.

No, the biggest issue you'll face is the interconnectivity in the harness...nothing stands alone and a (apparently) simple mod to one circuit can have cascading effects throughout the whole system.

When I did the harness in my FD (needed because of an engine swap) it ultimately became obvious that it would be simpler to start from scratch than to work around the stock components.

Such an approach requires extensive study of the stock wiring (you can't change things if you don't understand what they're doing) but can result in a much more logical and smaller harness (why is the stock fuel pump relay by the headlights?).

Once you strip the interior to expose the body harness you can see the results of decisions Mazda made that were undoubtedly logical to them but may be a problem for you.
Case in point is the fusebox in the driver's footwell.
No matter where a circuit starts and ends, it's wiring has to homerun to the footwell so it can be fused.
Not only is the footwell a totally crap location in terms of accessibility but this means there is a ton of wiring crammed into a small space.
I split the fusing into three locations- all readily accessible- and discarded the stock fusebox assembly altogether.

The FC was built during the dawn of the Japanese love affair with computers and our CPU reflects that...formerly simple components (like turn signals) were integrated into a circuit board.
That's all well and good but when one circuit fails- even a minor one- you have to replace the entire unit to regain functionality.
I replaced the CPU with simple/cheap "mechanical" flasher units and ditched the luxury add-ons (like door ajar chimes, key illumination, etc.).
Now if something fails- say, the hazard flasher- two minutes and a $5 part fixes it.

Working with our electrical system is a big job- whether you're pruning out unused systems or completely redoing the whole thing- but is well worth the effort, IMO.

 

there are 2 relays up by the front pass headlight... anyone know what they are for?

 

On a S5 NA that's the fuel pump resister relay.

 

but the same on an S4?

 

if you are talking engine harness only, just make one. It will be a lot easier and nicer in the long run.

 

Anyone iknows about what i need to keep fron the harness of a rx7 into a starlet??