LX570 Passenger Seat Heater ECU - Possible Solution

[Omsok]

Problem solved!

After consulting with another LX owner on an LX570 Facebook group, he figured it out. We both had exact same troubleshooting steps: checking all the fuses, under-seat connectors, switching out ECU and the only thing that was missing was a plug that was located behind the seat-back area. See pics below:

This is what it looks like after you remove the back cover of the seat. It's a relatively straight forward process. Loosen two bungee straps on the bottom, remove two screws in the mid-section, then pull the backing downward to remove.
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After taking off the back cover, there's one white plug that's right next to the vent. Upon a closer look, the wires attached to the bottom portion of that plug had somehow broken clean off.
View attachment 3260518

To fix this issue, I had to break off the last hanging wire, re-pin the entire plug with new wiring and then solder the new wires onto the existing wiring harness.

View attachment 3260522
To remember which colored cable goes where, I marked the original locations with G (grey), Gr (green), B (blue), and R (red).

View attachment 3260524
I added some solder to the pins to ensure the connections are secure.

Now solder them to the existing wiring harness.
View attachment 3260529

Once that was done, I plugged it back in, and Voilà! The heat/vent both work now. I hope this helps those who are still struggling with their broken seat climate issues.

Any tips on getting the seat back off without breaking stuff?

I am good at breaking connectors and plastic trim pieces.

 

[Omsok]

Finally got it done. Ordered a 2008 LEXUS LS460 FRONT LEFT SEAT CLIMATE CONTROL MODULE OEM 85861-50112.

I had previously tried swapping my driver's side ECU to my passenger side. This got the seat heat/fan switch to illuminate,e but did not get the seat fan to turn, or for the seat to heat up.

After ordering one for a 2008 LX, it seems as long as the connector plugs look the same they all work for front, left, right, rear as long as they are in the similar age group, at least for my 2008 LX570.

After swapping the aluminum case and PCboard so th new to me ECU woudl mount under my seat in the original ECU box/case, I had the same issue. The heat/fan switch would illuminate,e but the seat woudl not do anything in the HVAC department.

Remembering seeing another member's post about a little wire behind the shoulder area of the fort seat, I removed the seat back, and lo and behold a snapped thin wire. Instead of following what th either poster did, a better job, I just ran a jumper wire and used a solder connector and shrink wrap and taped it in place.

Fan immediately started working with Start / stop switch on, and no need for weight on the seat (I was unsure) See attached photos. Let me know if you need any details. Happy to have this little niggle fixed. Now for the cruise control switch that doe snot respond accurately, and sometimes not at all.