Hmmm. This is interesting. So we took the M on a road trip to Philly the other day and about an hour into the drive we smelled a kind of popcorn/waxy smell. I had turned her seat heater on about 15 minutes before in a attempt to stave off a request "to at least turn the temperature up if I'm going to drive this way". We both noticed the smell at the same time - it hit quickly - and I immediately turned off the seat heater and apologized for farting. The smell dissipated and I wrote (in invisible ink) a mental note to take a look at the bottom of the passenger seat. While I had hopped maybe she had farted and was trying to play it off, or maybe her new cardigan fluffy sweater was melting with the seat heat, I am betting I know what I'll see.

While it's very much in my nature to completely identify an issue without actual investigation, in this case it's still like 40 degrees out and I'm only one beer into the afternoon. Lemme grab my wrench and take a look...

satown210 wrote: ↑

Fri Jan 03, 2020 11:34 pm

mrnix wrote: ↑

Thu Jan 02, 2020 11:11 am

As a follow up and heads up to anyone performing this repair, mine shorted out a second time. It seems that the first time, only one wire scorched and melted the connector terminal. It was the 2nd wire from the side as shown in my post above to which I added a fuse. The first wire from the side proceeded to melt (similar to Crrraig's picture) so I had to perform the repair a 2nd time so if you're doing it, add fuses to both of the wires just in case. It seems all right now since I fixed it a 2nd time a few weeks ago. Good luck to anyone that does this, but it's well worth giving it a shot if your heated/cooled driver's seat has shorted out like many apparently have. I can only imagine this is a $2000+ repair at the dealership since they would likely replace the entire harness and module - only to probably have it short out again due to poor design.

You've clearly got something wrong and I doubt it is the wiring. You are fixing the symptoms but not the cause. WHY is it shorting and melting wires? You have a fire risk developing.

That's why I added the fuses where Nissan originally should have. Based on my research online, it seems this is a common issue with Nissan's wiring for ventilated seat modules.

I was really hoping that I would have found some cooked plastics under the passenger seat, but everything looks fine. Now I need to check her sweater for singeing.

Of course passenger seats see a lot less occupancy, but I was surprised at the seat filter discoloration. I was expecting to find a almost new filter and instead I found enough to be able to change the color by cleaning. While I am thinking of it, I probably should swap seat filters... or I guess I could cough up the $15 for a new filter on amazon (they are Motorcraft FS100 filters it seems). I'm so surprised with the filter condition as the seat looks perfectly new. No lard a** has been sitting in that chair for 100% of the miles. Conversely, the drivers seat totally confirms that a Fat Bastard has been behind the wheel of this beast for its entire life.

Wife is one of those lighter models and I'm guessing previous owners passenger was of normal/light weight too as it seems the seat was occupied quite a bit (filter condition). I was hoping a burned up connector may rule out the thought of crushed passageways (other threads suggest) restricting flow and overheating the motor causing increased current draw.

Since I need to go back under the drivers seat to replace the 15amp fuse with a 10, and evidently add another fuse to the ground side (I did buy two fuse holders - Sagan's 'Contact' taught me to always buy two, and yes, I have a spare M sitting in my spare house's garage as we speak - shhh! don't tell the wife or the spare wife, please), I think I may whip up a current monitor with a raspberry pi and let that grab some numbers for a while. It would be interesting to see how that Peltier plate warms up - betting huge spikes at first when you put it on position 3 from freezing cold base temps. I'll do this right after I get the oil to stop leaking out of all these damn BMWs.

Now I'm terrified to use my seat heater. First, I'd better take a peek at my seat heater connectors.

I wouldn't be, I've been using the heck out of mine, brazenly putting it on "3" when the car has been sitting out in the teens all night. Just checked the connector the other day and it looks absolutely fine.

I still haven't looked into why my passenger seat made the smell it did, but I'm betting someone spilt their cafe-mocca-frappa-chino and didn't tell me. I haven't been in the M much this week as the dealer I bought that used high millage BMW E90 from has now taken pity on me because it turns out they can NOT stop the oil leaking out of that excellent purchase (I still have not taken possession of the car that I bought Dec 7th!). They have loaned me a new A4 until they have this 'worked out'. The A4 is very techy, big digital dash and all that, but not as nice to drive as the M. Being a basic optioned A4, the seats leave a lot to be desired. 0-60 using the paddles is nice, but engine tone is not. It seems a VW overall.

So, to recap, you can get (use of) a new Audi A4 simply by buying a well-used BMW from a Audi Dealer and negotiating to get them to "stop the oil leaks"!

Sorry, I get distracted easily. I did get in all the bits to start data logging the seat heater power draw - just need to assemble everything, write some code, and have a few cold mornings again.

I've had issues with my climate seats on the driver side since I got the car at around 69k miles (now at 80). At first they would blink the light on the switch and then after a few blinks go out and after replacing the filters they seemed to work for about a week. After that week I would not get any blinks at all so figured it was time to check the plug and I'm glad I did. Everything looked fine at first but I was unable to remove the plug. I even tried pliers to no avail - ended up using a heat gun just to soften up the plug as it seemed welded to the control case.

Below is what I found

Outside doesn't look too bad but notice the connector has a melted section


From inside of the control unit you can see that it cracked the housing.


Another view from inside.


Connector removed.




Control board removed.


Backside of control board.


Solder joints of connector


I've already ordered a new connector and pins - hopefully resoldering the joints will help the control board and it's still usable because it looks like a $250 part.

Wow. Those are amazing pictures. Good stuff!

The board looks in good shape. No visible damage, apart from some localized blackening around the surface mounted (SMD) resistors nearest those 2 melted pins. So. if the board's high current devices are OK, that leaves arcing as the main cause for the burns. Arcing within the connector itself (like momentary sparking of contacts within a switch). That means the issue is most likely caused by loose connections for those 2 burnt pins (V++ and GND). Perhaps the socket itself needs to grip a bit tighter around those 2 pins? (eg, replacement socket)

did anyone find a more permanent solution to this issue? I'm back 2 years later doing it a third time. I'm sadly a pro at it by now.

When climate seat controllers burn up more than once it usually means a problem with either the Peltier plates (Nissan calls them TED's for Thermo-Electric Device) or the airflow. Peltiers work by producing cold on one side and heat on the other when DC current is applied, and which side is which depends on direction of the current. When the hot side isn't sinked sufficiently by airflow, the current it demands rises. That loads up the FET's in the controller and gets them hot, and eventually heats the controller's ground pin to where the plating is compromised. Then the ground pin becomes a resistor, and you can see the ultimate result in the pics. So there are four common things that all need to be right to keep the system healthy: Good plates, a good filter, a good fan, and no blockages. The plates are easy enough to check with an ammeter. There isn't exactly a spec for them, but they don't fail very often so comparison will spot a bad one that's drawing much more current than its companions. For the airflow, the volume of air from the ejection port is what matters, and a comparative feel test will generally spot a slow fan or an obstruction.

How do you test the plates? I assume a standard multimeter would suffice?

VStar650CL wrote: ↑

Sat Mar 26, 2022 1:35 pm

When climate seat controllers burn up more than once it usually means a problem with either the Peltier plates (Nissan calls them TED's for Thermo-Electric Device) or the airflow. Peltiers work by producing cold on one side and heat on the other when DC current is applied, and which side is which depends on direction of the current. When the hot side isn't sinked sufficiently by airflow, the current it demands rises. That loads up the FET's in the controller and gets them hot, and eventually heats the controller's ground pin to where the plating is compromised. Then the ground pin becomes a resistor, and you can see the ultimate result in the pics. So there are four common things that all need to be right to keep the system healthy: Good plates, a good filter, a good fan, and no blockages. The plates are easy enough to check with an ammeter. There isn't exactly a spec for them, but they don't fail very often so comparison will spot a bad one that's drawing much more current than its companions. For the airflow, the volume of air from the ejection port is what matters, and a comparative feel test will generally spot a slow fan or an obstruction.

An inductive clamp ammeter around one of the wires is what we usually use. Since most people don't own one of those and un-pinning the control unit connector can be a PITA, you can get the elements good and hot (say, 10 minutes running time on Max Cold) and then ohm the element. Problem children will read much lower ohms than healthy ones. The WD to identify the right wires for your M is here on SE-25:
https://www.nicoclub.com/service-manual ... 2%2FSE.pdf