NC Hardtop wiring harness for demister??? How to connect???

Luke · Postby **Luke** » Sun Aug 15, 2021 4:39 pm

Hi All
Anyone out there with a NC with hardtop fitted that has their demister connected?
I am having trouble with the NC wiring harness for the rear demister on my hardtop.
When I say hard top I do not mean the PRHT.
I mean the soft top model with the clip on hardtop.

My NC came with the hardtop when I bought it but was missing the wiring harness for the hardtop.
I bought one earlier this year from MX-5 Parts UK, but have not had the hardtop on the car so never fitted the harness.
It is Mazda Part number NF77-67-SH0A

I put the hardtop back on the car yesterday as clearly there will be no more track days in NSW this year.

The harness connects no problem to the hardtop.
But where do you plug it into the car???
On a NB you just used the existing cable from the soft top demister to connect to the harness.
I thought the NC would be the same.
The NC soft top demister has an inline connector as well. But it is completely different to the one on the harness. It is just a much smaller 2pin connector where as the hardtop one has a multipin connector(only 2 wires though) and an inline connector Velcroed to it as well which I have no idea what it is for.
The soft-top demister cabling goes in behind the plastic in the parcel tray and I know how difficult and time consuming that is to remove as I have done it once before to get to the Bose Amp when it failed. So I am hoping no one tells me it needs to be connected somewhere under there.

I have pictures of the wiring harness and the connector on the hardtop as below.
Sorry did not get one of the soft top. It is just a much smaller white 2 pin connector.

Anyone out there with a NC with hardtop fitted that has their demister connected?

bruce · Postby **bruce** » Sun Aug 15, 2021 7:26 pm

Possibly an option so you have to buy another bit of wiring which somehow connects to the rest of the car?

madmort · Postby **madmort** » Sun Aug 15, 2021 7:49 pm

Hi Luke, I have a removable hard top with demister for my NC, I'll look tomorrow and see what connections I have.
It was not plugged in when I took delivery of the car but it's an OEM unit that was purchased new with the vehicle originally so should have the right connections.
I'll report back.
Cheers

Luke · Postby **Luke** » Sun Aug 15, 2021 8:00 pm

bruce wrote:Possibly an option so you have to buy another bit of wiring which somehow connects to the rest of the car?

That is what that wiring harness pictured is supposed to be for.
When you order the hardtop it comes with a fitting kit.
My car had all the bits installed bar the harness. I even have the original bits that were replaced by the fitting kit.
You can buy the fitting kit separately as well as the harness individually so it seems Mazda put some though into it based on what happens in the real world.
Ie it is easy to lose the harness. Or when someone sells a hardtop quite often they don't remove the fitting kit and leave it in their car.

Google is broken for this as it appears not too many people around the world have NC's with hardtops.
I have found videos of people installing a top but they never connect the demister.
Also seen articles on how to adjust the height at the rear for a better fit.
Have also found links to the official Mazda instructions, but none of the links work.

I have emailed MX5partsUK to see what they know since I bought it from them, in December last year apparently.

madmort wrote:Hi Luke, I have a removable hard top with demister for my NC, I'll look tomorrow and see what connections I have.
It was not plugged in when I took delivery of the car but it's an OEM unit that was purchased new with the vehicle originally so should have the right connections.
I'll report back.
Cheers

Thanks mate.

madmort · Postby **madmort** » Mon Aug 16, 2021 9:50 am

This is my setup with the two pin on the left of picture with the harness going to the block on the panel. Problem is I don't know where that main harness comes from.
Not much help but here is a pic.

IMG_2578.JPG

P.S. On a second look the main harness comes from under the plastic tray/liner.

bruce · Postby **bruce** » Mon Aug 16, 2021 4:10 pm

Is there the extra switch for the demister, like in an NA?

madmort · Postby **madmort** » Mon Aug 16, 2021 5:08 pm

No Bruce I think it's on the heater control dial/push button, but not to sure what the image means. I'll look it up.

P.S. It's definitely on the heater control knob, press for rear defrost.

Luke · Postby **Luke** » Mon Aug 16, 2021 9:44 pm

madmort wrote:This is my setup with the two pin on the left of picture with the harness going to the block on the panel. Problem is I don't know where that main harness comes from.
Not much help but here is a pic.IMG_2578.JPG
P.S. On a second look the main harness comes from under the plastic tray/liner.

That black one right there in your picture is the one.
MX5 parts UK have sent me a picture of exactly the same thing.
I did not notice it when I was digging around in there on the weekend.
Will be a hard top off job to have a look again. Have to wait a few days when Dad and I are not on opposite shifts.
There is a very good chance I buried it under the plastic when I changed the BOSE Amp and fuel filter last year. If so, I am not pulling all that out again. There is a reason a fuel filter change in a NC costs a fortune. It takes many hours to disassemble and reassemble all that plastic.

And now I am seeing the point of the extra inline connector in the new harness I have.
When you unplug the existing connector you plug it into that dummy receptacle so you don't have the unplugged cable just bouncing around in there.

madmort · Postby **madmort** » Sun Aug 22, 2021 3:20 pm

How did you go Luke, manage to find the main harness? Got the hardtop off yet? Mine has a gap between the plastic panel and the floor, maybe it's hiding under the panel and you might be able to get a hand underneath and feel for it.
Just for the record mine was not plugged in all winter (Lazy) and never, once, had a fogging issue.
Cheers

Luke · Postby **Luke** » Mon Aug 23, 2021 4:02 pm

Uh, nope. Totally forgot.
I guess doing 3 12 hour nights does that to ya.
Guess It will be next weekend now.
Coming off dayshifts so the brain should be more engaged.

madmort · Postby **madmort** » Mon Aug 23, 2021 7:40 pm

Get it Luke, did rotating shifts for 10 years.
Cheers

Luke · Postby **Luke** » Sun Aug 29, 2021 11:49 pm

...
Was meant to do it this weekend but Dad did overtime shifts.
I had a feel in there with the very limited space with the hardtop on and soft-top folded down.
I can feel the holes in the plastic where the plug should be clipped to, but I cannot obviously dig under the plastic with the top folded down.

Hopefully can look on Friday. Dad and I are both off on that day.

93_Clubman · Postby **93_Clubman** » Mon Aug 30, 2021 6:15 pm

Luke, if NC HT wiring is anything like NA & NB HT wiring, it fitted for, but not with the HT demister relay. On the NA & NB the relay ,when fitted, lives just behind the rear panel of the boot.