- My model of MX-5 is 20th Anniversary 2010
- I’m based near: Essex
- I’m looking for technical help or recommendations on: non-standard leather seats which were fitted before I purchased the vehicle. I can’t locate a switch anywhere to turn off the passenger hearted seat.
Pictures would help, sounds a strange one.
How does the drivers seat operate heater wise?
Odd one, I don’t think the 20th anniversary model came with heated seats but it may have been possible to order when new. The switches are normally to the right of the 12v power point.
So are these non standard seats actually from a MX5 and if so which model (as MickAP says, a photo may help).
How far have you traced the wiring? Any sign of non standard fuse’s?
The normal fuse is number 4 in the internal fuse box on the passenger side kick panel, is there a fuse fitted there?
Coconino you are correct, they came with cloth seats so not heated.
Still a strange one one that a retro fit of leather seats (NC standard) and the passenger one is heated, working I presume. It can’t be possible without switches.
As i say pictures to determine what you have. You can get under the seat (seat out of the car) and pull the wire from the block under there, it must be live though
Still a strange one unless the previous owner has been playing electrical whizz and failed.
Thank you MickAP and Coconino for your responses. I have attached photos. The driver seat doesn’t seem to be switched on. I haven’t had a go at tracing wiring yet. I’m wondering whether I can simply pull a fuse, but don’t want to make matter worse for myself! I’ve spoken to an auto electrician who quoted me £60 try to solve the problem.
That wiring looks aftermarket to me, maybe a previous owner wired the seats to be on permanently and the driver’s side one has failed.
Just disconnect the heater plugs under the seat and tape up the car side plug. Alternatively if there is no on/off switch you could connect a MultiMeter or 12v light bulb acroos the connector and work your way through the fuses until you find which circuit was used for the supply.
I have retro fitted Front Fog lights to my car and found that the supply harness was pre-installed on the wiring loom, just taped up and made redundant at the factory. Maybe the Heated seats are similar ?
Fuse 4, the yellow 20 amp in the upper half of the fuse box is only listed as “seat warmer”, on the off chance that the previous owner has picked up a live feed there (maybe from original wiring). Remove the fuse and see if that does the trick.
So assume no on/off switches fitted?
Someone correct me if I’m wrong, is the wiring all there in the loom to connect up heated seats, just the switch panel required to be installed under the heater controls?
Looks as Robbie suggests the previous owner had there own ideas about wiring them up.
There should have been a multi connection block under each seat for heated seats, air bag and seat belt warning wiring (sensor)
Perhaps the previous owner just swapped the seats out and connected the loom under the seat but never actually finished the job. Hence why you have no switches. 
If that’s the case then seems pretty daft.
Just an opinion.
I think the wiring is all there it just needs the necessary connections under the seats and the switches under the heater control panel. My non heated seat SE certainly has the seat warmer fuse in place and I think I remember a couple of unused switch connector blocks where the switches would be. I wonder if the previous owner has connected the supply to the seat at this point, rather than fitting the switches?
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Makes me wonder that, easier perhaps to source some NC1 switches.?
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All of your comments/suggestions gratefully received. I will keep you posted how I get on.
The wiring diagrams in the American 2008 MX-5 Workshop Manual show connectors on the coloured wires. This is useful.
But bear in mind the L-R transposition of the dash panel, seat, etc, and some control legends on the drawings. Most of it is about right for us so it can be a very useful initial guide. Dive into it and you can soon see the significant differences.
Good luck.
I think the heated seat switches are in the same position on both rhd and lhd so the wiring should be the same on both? The wire colour coding should also be common.
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Hmm, maybe not quite. It is very easy to be confused here.
Here is a pic from under the drivers seat of UK 2008 NC with seat heaters and side airbags.
The Brown/White and Blue/Red pair of airbag wires (my guess) appear to match USA driver’s side, but the other wires are not quite the same.
The Green and Black/Blue could be seat heater. Green and Black in USA.
But what are Pink and Black? More about the seat heater? Wrong colours for the ‘Buckle switch’ mentioned for USA. (Grey and Yellow/Green)
Are Black/Blue and Pink actually across the thermostat, and only Green and Black the actual heater feeds from elsewhere?
I remember seeing something about them from a few years ago, but just what it was has floated out the open windows in my mind.
I’m sorry not to be more helpful. But this does illustrate how the USA wiring has similarities to UK, and yet also significant differences.
Could the pink / black wires be for the occupant weight sensor.? I don’t think the early seats had any thermostatic control other than maybe an overheat switch / sensor built into the pads.?
The US wiring diagrams are not terribly clear and UK ones seem difficult to come by.
Not on driver’s seat, and again wrong colours (USA passenger seat; Red/Blue, Black/White, Black/Yellow).
Thanks again everyone for your posts. I have discovered both seats have a discreet rocker control switch. which I missed. I won’t lie, I feel a bit embarrassed!
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At least you sorted it and brought a smile to my face. 