Driver’s side heated seat not working, light in switch illuminates but neither base nor backrest pad heats up.
Can anyone suggest where I should start to look?
Thanks.
Jerry
Is there an occupation sensor to only switch the element on when someone is sitting there.
If not a multimeter to check voltage to the connector under the seat.
No occupation sensor.
I’ll try to borrow a multimeter.
The heated seat elements are controlled by relays. On mine you can hear them activate when the switch is pressed.
Going by the sound, the relays are located under the dashboard by the drivers right knee.
Try swapping them over. That’ll check if one relay has a fault. Even with the switch illuminated, if the relay is faulty there will be no power out to the seat heating elements.
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Thanks.
They are both ‘clicking’, but I’ll swop them over when get the chance.
If both relays are clicking you’ll probably find both are functioning.
I’ve never had to look under my drivers seat, but I would assume there must be a connector in the wiring for the heater elements.
I would try to probe the connector for 12V when the switch is pressed.
Best of luck.
There are two obvious connectors, one under the front of the seat and one under the back.
There are 12 volts at both of these when switch is on and none when switch is off.
Are the connectors two pin? If so the earth return will be through the connector.
If you are getting a switched 12V to the connector then the relay is functioning.
I would next try a continuity test through the connectors on the wiring running up into the seat. Depending on the element resistance, I would expect a reading of 10 to 20 ohms would confirm an intact element.
An open circuit reading will indicate a broken heating element.
Best of luck.
It may well eath through the seatbelt coupling and that only works when the seatbelt is connected to the coupling check tht the earth lead does indeed connect to earth.
Thanks guys.
Yep, two pin connectors.
Getting a bit complicated for an electrical dummy like me but I’ll try.
(Bear in mind I don’t really know how to use a multimeter).
I can’t access the connector on the front, but the one on the back gives no reading.
The rear connector on the working seat gives 1 ohm.
The reading on the working seat of 1 ohm means a current of 12A from the 12V battery when the seats are being heated.
That could be about right, it would also mean a 12W heating element, or a 6W one in the seat and another 6W one in the backrest connected in series.
If you have your multi meter set to resistance or ohms and you get a reading of flashing zeros when you probe the non functional seat connector, then you have an open circuit, hence a broken seat element.
If the base and backrest heater elements are connected in series, then when one element is damaged,the other will not function either.
Looks like your problem is with one of the heating elements inside the seat. It’ll only be the one, it’s highly unlikely the other element would go open circuit at the same time. It’s now just a question of finding which one, base or backrest.
Hopefully someone on here has stripped the seat down and can advise you further.
Best of luck.
I’m sure there’s a post somewhere about someone fixing an element in the seat. From memory it involved removing the seat cover. Once that was done the break was immediately apparent as there was some discolouration due to heat at the break. A small section of wire was soldered in place and the problem cured. I have no idea where the post is, you’ll have to search if you want to find it. Good luck with the repair.
Thanks guys, brilliant help all round.
Connected in series seems likely.
As long as I fix it before next winter I should be OK with the wife!
Your maths is a little out, 12A on a 12V system is 144W not 12W.
Also two 6W heaters in PARALLEL would give you 12W
Of course it does. W = IV
That’s what I get for posting with brain disengaged.
Well corrected.
Found the guide.
http://www.mx5oc.co.uk/forum/yaf_postst78170_Fixed-seat-heater-----with-photos.aspx
Need to resurrect this thread. Help!
My mk2.5 sport has had a dodgy drivers heated seat since I got it. The passenger one always worked, switched on, warmed up (only slightly) and telltale light came on. Drivers side: never worked, telltale stayed off, no clicking from relay.
So after pulling both the seats and testing them, turns out they both show a solid 2 ohms so no breaks in the seats themselves, roughly 6 A must go through them which is probably right on a circuit fused at 20A. Fuse is fine by the way.
Tried swapping relays over and the drivers seat seemed to work and warm up on the other relay. Great, just get another one off eBay and then will have a working pair. The weird thing is I now have two relays that seem to work when places one way around, but not the other ie the telltale light won’t come on with them switched around. Surely either both are working or one, or none. They can’t be position Dependent? does this mean the switch itself is knackered?
i now have two superficially working relays, and a superficially working switch with two working tell tale lights. The seats warm up very slowly and feebly if at all! What is going on?
One last thing - when connected the relays the wrong way (giving one working Light) the Other relay got really hot, and the working one was warm. Now I’ve got both relays swapped round they are both warm. Should they get warm at all?
Hello,
I have a 2002 MX-5 NBFL Sport. Its driver’s side heated seat has just stopped working.
It’s currently in for its annual service at a Mazda dealer who advised that the two heater pads - ND55-88-11X and NC84-88-122 are no longer available from Mazda U.K., Europe or Japan.
I’ve seen some after market kits available from MX-5 parts. I want to use the original dash switches and phoned MX-5 parts but they don’t know if it’s possible.
Does anyone have any idea if it’s possible and an auto electrician to trust to job to?
Cheers!