LX570 Passenger Seat Heater ECU - Possible Solution

[turbotwo]

I purchased a 2010 LX earlier this year, and noticed fairly quickly the passenger side seat heater didn't work. My first assumption was that it would either be a fuse or a switch, but after finding a handful of threads I learned, that the most likely culprit was the seat heater ECU, which is quite expensive. In one of those threads, @lx200inAR speculated that the ECU from an LS could potentially be used instead since the plugs are the same. Since this seems to be a recurring issue for some owners, I wanted to figure it out. So instead of buying a new LX ECU for around USD $400, I bought a used LS ECU for about USD $19. The case for the LS part has different mounting points, so I simply pulled out both circuit boards and swapped housings. Here's the side by side photo (left side LX, right side LS):

They're not identical, but they're very similar! Also upon inspection, my ECU has signs of damage in the exact same spot as images posted by @Cruisin911 in one of the other threads (top right side in the photo below):

Anyway, plugged in the new/used ecu mounted in the LX housing, and the switch lights up, the fan turns on, and I have heat!

I'll update this thread over the next couple of weeks if I notice any issues/side effects, but for right now the problem seems to be solved! The part number for the LS ecu that I bought is 85861-50052. According to the eBay seller it came off of a 2007 LS460.

 

[lx200inAR]

I purchased a 2010 LX earlier this year, and noticed fairly quickly the passenger side seat heater didn't work. My first assumption was that it would either be a fuse or a switch, but after finding a handful of threads I learned, that the most likely culprit was the seat heater ECU, which is quite expensive. In one of those threads, @lx200inAR speculated that the ECU from an LS could potentially be used instead since the plugs are the same. Since this seems to be a recurring issue for some owners, I wanted to figure it out. So instead of buying a new LX ECU for around USD $400, I bought a used LS ECU for about USD $19. The case for the LS part has different mounting points, so I simply pulled out both circuit boards and swapped housings. Here's the side by side photo (left side LX, right side LS):

View attachment 3180967

They're not identical, but they're very similar! Also upon inspection, my ECU has signs of damage in the exact same spot as images posted by @Cruisin911 in one of the other threads (top right side in the photo below):

View attachment 3180970

Anyway, plugged in the new/used ecu mounted in the LX housing, and the switch lights up, the fan turns on, and I have heat!

I'll update this thread over the next couple of weeks if I notice any issues/side effects, but for right now the problem seems to be solved! The part number for the LS ecu that I bought is 85861-50052. According to the eBay seller it came off of a 2007 LS460.

That's awesome....but now there's going to be a run on those LS ECUs and the price of those will surely go up....it will be a race to Ebay. Haha

 

[turbotwo]

Haha good point, I should buy a couple more to get ahead of it!

 

[Bryanmc]

Very interesting! My driver seat one has stopped working, but I haven't done any troubleshooting. I just picked up an LS model from eBay for $36. I figure it's worth the chance!

 

[RunTheDistance]

Awesome! I bought one of those LS units recently with the same plan. It's sitting on my bench right now. 24 degrees here right now so maybe good installation to knock out this project.

 

[turbotwo]

Awesome! I bought one of those LS units recently with the same plan. It's sitting on my bench right now. 24 degrees here right now so maybe good installation to knock out this project.

Nice, hopefully it works out for you as well! If you can, report back here with the part number of the ECU you have, and let us know how it works out.

 

[NYC570]

Anyway, plugged in the new/used ecu mounted in the LX housing, and the switch lights up, the fan turns on, and I have heat!

Your fan turns on when you turn on the heated seat?

 

[turbotwo]

Your fan turns on when you turn on the heated seat?

No sorry, it turns on when I turn the knob to the left, the "cooled" seat side.

Also now after using it for a couple of days, it seems that the passenger seat is only being heated from the lower back portion. The heat doesn't seem to be coming from the seat cushion itself like it does on the driver's side. Since this vehicle is new to me, I don't know if this is a separate issue, or attributable to the LS ECU.

Either way I'm still satisfied at this point, however it will be interesting to hear from anyone else who tries it to see what their results are.

 

[Bryanmc]

Does the seat cushion typically heat throughout the entire bottom? Both my passenger and driver seats have always only heated from the front part of the bottom cushion. I don’t know if that’s normal or if the heater has been partly broken since I got the truck.

 

[lx200inAR]

i ordered a front and rear passenger side ECU. Mine works fine, but figure it's precautionary and maybe can do some research with Techstream to see if it shows up any different to the truck. Also, my seats work, so a good test base. It would be a real boon if the rear ECUs work. They go for less than $15 w/ shipping. (The rear seats in the LS have full heating/cooling and the same knob that the LX controllers use).

You might double check all your connections underneath your seat, make sure you didn't miss reconnecting something. If nothing else, if you could identify which wires off the ecu are for the seat heaters, you can check to see if there is voltage to them when the heater is turned on.. That's probably difficult though, it's probably not easy to have the seat ecu plugged in and leads testing cables.

 

[bloc]

This is great tech, thanks for posting

 

[LXstatic]

Well, I have a 2015 LX and I noticed today that the light is staying on, on the switch. It still seems to function properly. Just kinda weird the light stays on. Anyone had this? Also, noticed the front passenger door handle has stopped unlocking when you touch it… gremlins rearing their heads?!

 

[STLandcruiser]

I’ve got a 2013 LC and Neither front seats heat/cool work properly. Driver’s side won’t shut off and the passenger side doesn’t engage at all. Would this ECU work for a 200 series?

 

[LXCruza]

That is awesome. Off to eBay I go...

 

[LXinOBX]

Posted somewhere in here is my identical saga ('10 LX) passenger seat kept going out, replaced ECUs several times. They would work fine for about a month or two, then "no light".

Finally we dug into the passenger side kick panel and cleaned up connectors, the suspicion now being maybe a clogged sunroof drain port had contaminated the area. Anyway, we cleaned it all out, including the connectors - and (knock wood) it's still working.

The jist of it all was that perhaps the corrosion (back up due to clogged sunroof drain) on the assy connectors in the kick panel may have increased the impedance to a point that after a while the ECU just burnt up

 

[Mr45]

I purchased a 2010 LX earlier this year, and noticed fairly quickly the passenger side seat heater didn't work. My first assumption was that it would either be a fuse or a switch, but after finding a handful of threads I learned, that the most likely culprit was the seat heater ECU, which is quite expensive. In one of those threads, @lx200inAR speculated that the ECU from an LS could potentially be used instead since the plugs are the same. Since this seems to be a recurring issue for some owners, I wanted to figure it out. So instead of buying a new LX ECU for around USD $400, I bought a used LS ECU for about USD $19. The case for the LS part has different mounting points, so I simply pulled out both circuit boards and swapped housings. Here's the side by side photo (left side LX, right side LS):

View attachment 3180967

They're not identical, but they're very similar! Also upon inspection, my ECU has signs of damage in the exact same spot as images posted by @Cruisin911 in one of the other threads (top right side in the photo below):

View attachment 3180970

Anyway, plugged in the new/used ecu mounted in the LX housing, and the switch lights up, the fan turns on, and I have heat!

I'll update this thread over the next couple of weeks if I notice any issues/side effects, but for right now the problem seems to be solved! The part number for the LS ecu that I bought is 85861-50052. According to the eBay seller it came off of a 2007 LS460.

Just ordered one for my inop pax seat. Where is the ECU located?

 

[lx200inAR]

Just ordered one for my inop pax seat. Where is the ECU located?

On the underside near the front. You can remove the 4 seat bolts into the floor and then rock the seat back. There are three connectors to disconnect I believe, 2 for seat controls and one for airbag. but it’s been a while since I’ve done it. The airbag one is tricky, has a double release system.

There are also 2-3 connectors from seat v bottom to seat back. Make sure those are all connected before you go too far down rabbit hole of replacing ECU.

 

[Leaky2014]

Well, I have a 2015 LX and I noticed today that the light is staying on, on the switch. It still seems to function properly. Just kinda weird the light stays on. Anyone had this? Also, noticed the front passenger door handle has stopped unlocking when you touch it… gremlins rearing their heads?!

You got a water leak.

 

[Everlong]

Any idea on drivers seat simply not heating? knob works in cooling and is lighted?

 

[mzhu]

My driver-side seat won't heat or vent. The control knob lights up but nothing happens. Following what others did, I got an LS driver-side ECU from eBay and did the swap, but the seat climate functions still don't work.

Next, I checked all the fuse boxes in the engine bay, driver's side, and the passenger side... all were good.

What else am I missing here?