In trying to diagnose my irrational oil pressure readings. I found a mystery wire hooked to nothing.

it’s black with white stripe and red dashes and a spade connector. What is it?

 

Hard to say but if you go to Foxed.ca - Mazda RX-7 Manuals, the manuals online can probably help some.

 

The oil pressure connector is a clear/white connector with a slot on one side that slides over the mushroom shaped sensor under-to-the left-of the oil filter.

 

My 85 GS has a wire coming out of the harness on the driver side that was just coiled up and not attached to anything. It was either bundled up on the steering gearbox, or on the clip under the beehive oil cooler, I can't remember which. But my car runs fine without it out connected, and there isn't a clear place to connect it to so...

 

That MAY be for the cold start assist thermoswitch in the oil pan. It's next to the oil level switch.

 

If it was coiled up on the chassis side near the gearbox, that may have been for the variable assist unit for power steering equipped cars.

Mazda used the same wiring harness in all cars. Periodically you'll see someone say "I connected two wires at the shifter and now my dash lights don't work." The PRNDL light for automatic cars used a male and female bullet connector, and they just dangle there for manual cars, connect them and you short the lighting circuit. Fortunately, the fuse is protected by the dimmer module burning up first.

 

That's what I figured. I have neither power steering, nor cold start assist, so i think i'm good!

 

I just spent some time looking at all the wires in that area of my '85, and I'm looking at this differently.
As KansasCityREPU pointed out, it's not the oil pressure sensor line. It's also not the temp sensor line, or the radio frequency thingy either, both of which are bullet connectors and come over the engine from the pass. side.

Your wire looks like it's coming from the driver side fender but I'm wondering if it goes back to the front/top/ left of engine, from harness behind the alternator. The picture doesn't show enough to be sure, but... On my 12A car there are 2 wires there that go down to the front left oil pan. One fat one with a white connector goes to the low-oil level sensor and the other thin wire, with a spade connector, goes to some mystery probe right behind it in the pan.


Follow that wire back and see if we're looking at the same thing. My stock '85 12A has it, but my new '85 13B does not....


So Ottoman5000, have I identified your mystery wire, and if so, what do I win?

Everyone else - what the heck is this probe? And why doesn't the GSL-SE 13B have it? Now I'm gonna have the same dangling mystery wire when I swap engines.

EDIT - just saw Peejay's post #5. We're talking about the same thing, and thank you Peejay for telling me what it is. When I put the GSL-SE based 13B in I'll just tuck that wire back into the harness (I don't have the cold-start tank anymore).

 

You guys are amazing.

I spent sometime looking at the fox wiring diagram and found a black with white stripe that is connected to the ignition system some how, but don’t think this wire is long enough to reach any of that.

you my friend have won a place in my rotary heart and step up in the wankel platform system. Thank you so much guys

 

........and the 64 dollar question is: So what was it?

 

AC? There is a relay up on the driver fender near firewall on AC cars...guessing harness points pre-wired, AC or not-

Stu A
80GS
AZ

 

I had considered it was the AC wire too.