Extra wiring harness plugs?
 

So I have a 94 Factory Manual steering and non AC. I have a few unused plugs under the hood and near the battery. I tried to google them but I think I am using the wrong key words. I am assuming that all NA Miatas had the same wiring harness regardless of options. Here are some pics of what I am trying to identify. The single plug wire pic comes across the front of the engine and is chilling near the heat shield. The other plugs are on top of the driver strut bolting area. The ones in the trunk are near the battery.https://www.miataturbo.net/attachmen...ine=1466551660
https://www.miataturbo.net/attachmen...ine=1466551660

https://www.miataturbo.net/attachmen...ine=1466551660

#3 is an AC switch im pretty sure. Do you have AC?

From the factory. No AC, Power steering or ABS.

#1: White one is "probably" cruise control. The blue one is a source of 12VDC for maintenance use (power your timing light, whatever).
#2: Power Antenna
#3: Power Steering Pump Sensor to bump idle speed.

Yes, all US Spec Miatas came with the same harness. Uninstalled options result in unpopulated plugs.

Genius. Now that you call them out they all make perfect sense. I didn't even think about cruise control. I wonder if is worth going through the harness and cutting a lot of this crap out.

I avoid messing with the OEM harness to the greatest extent possible. Good rule to follow.

No to cutting things out. it will only make you hate your life.

They were close, but not identical. For instance, try getting a VSS signal out of a '92 that was made without cruise or an automatic transmission. Exactly one wire is missing from the instrument harness, even though the VSS sensor itself is there. And the worst part is that the wire IS there in the "front" harness (which connects to the ECU, cruise computer, etc), it's only missing from the "instrument" harness. So you think you have the wire when you're hooking up the ECU, but it only goes as far as Common Connector X-17, where the Front harness joins the Instrument harness.

I'm not sure about the later cars, but the 1.6s were filled with fidgity little omissions like that, where a single wire is missing if the car was built without an automatic, or cruise control, or power steering, or ABS, or autonomy from the Queen, etc. And in '93, California cars got their own completely separate set of harnesses, unique in all the world. The early wiring diagrams are full of these little notes:

https://www.miataturbo.net/attachmen...ine=1466557971

https://www.miataturbo.net/attachmen...ine=1466557971

https://www.miataturbo.net/attachmen...ine=1466557971


And so on... Makes no sense to me- it'd be a lot easier to stock a single harness in the factory rather than fifteen different versions of it? But they did. The parts catalog confirms this:

https://www.miataturbo.net/attachmen...ine=1466557971

Fifteen different versions of just the front harness alone, just for the '92 model year.


Gram strategy...


But yeah, everything hornetball said is correct with regard to identifying the connectors. The blue plug was indeed put there by Mazda to power timing lights and other dealer service equipment, since there's no battery under the hood to clip onto.

I confirm the guess about the cruise control actuator.

Huh?!? I was aware of the differences between US and Canadian harnesses, but never imagined they would have so many different harnesses in our market. Maybe auto vs. manual, but changing the harness for a cruise-control or power steering option? It's borderline "German Engineering."