Passenger seat issues with heat/cooling on 2011 LX570 (1 Viewer)

[Grumvee]

Hi folks!

Anyone here have experience troubleshooting issues with the front seat heating/cooling system?

I have a new-to-me 2011 LX 570. Driver seat works great.

Passenger seat doesn't: the switch doesn't light up, and neither the heat nor cool (nor ventilation) functions work. The ODB is throwing the following 3 codes:

1. B1421 solar sensor circuit (passenger side)
2. B1424 solar sensor circuit (driver side)
3. B1478 communications malfunction (seat A/C EDU)

Obviously, I'm a little nervous.

Not critical to me that these functions work, but would be great if they did.

Related question: what does it feel like when the system is working? With the driver side, I don't really feel any ventilation/blowing when it's just on ventilation mode. When it's on cool, after 5-10 minutes, the seat definitely feels cooler, but it's not like I can feel any air moving out of it. Is that normal? The prior owner recently had the leather dyed/reconditioned, and I'm wondering if that is somehow interfering with things. The perforations in the seat look normal to me (don't look "plugged" or anything).

Thanks!

 

[radman]

The solar sensor codes are irrelevant if it was dark when you pulled the codes. I’m not sure about the 3rd code...

as far as the other questions, the seats are only vented - no dedicated AC. There’s a little filter and fan down there that grabs air from the compartment and pushes it up through the seat. So if you have the heater on, it will blow warm air up. Can you hear a fan?

Seat climate control switch

Since my passenger side seat climate control (heat/ventilation) wasn't working, I decided to swap the switch with driver side and check if the switch itself is problematic. After opening the panel I realized the passenger side switch is different than the drivers side and the harness is not...

forum.ih8mud.com

 

[tacoduck]

The solar sensor codes are irrelevant if it was dark when you pulled the codes. I’m not sure about the 3rd code...

as far as the other questions, the seats are only vented - no dedicated AC. There’s a little filter and fan down there that grabs air from the compartment and pushes it up through the seat. So if you have the heater on, it will blow warm air up. Can you hear a fan?

Seat climate control switch

Since my passenger side seat climate control (heat/ventilation) wasn't working, I decided to swap the switch with driver side and check if the switch itself is problematic. After opening the panel I realized the passenger side switch is different than the drivers side and the harness is not...

forum.ih8mud.com

Interesting. My seat warmers work great. Seat vent appears to not effectively move air through the seat. Fan is on because I can hear it.

 

[LXCruza]

I have the same issue with passenger seat on my 2010 LX. Switch doesn't light up, and none of the ventilating/heating features work. I replaced the switch itself (part# 84751-60140) but it didn't help. I'm guessing the ventilation/heater ECU assembly under the seat needs replacing. Last I checked it was around $800-ish if I'm not mistaken.

 

[Hoosier Daddy]

A. You say the truck is new to you and recently had work done on the seats. Decent chance the seat was removed for that.

B. The code is for communication failure (ie, not connected).

Given A+B, the first thing I'd do is ensure the connector underneath that seat is actually plugged in and seated (no pun intended) correctly. You may need to unbolt the seat to do this.

 

[lx200inAR]

My recently-ish new to me LX also had "leather work" done to it pre purchase. The tech did not plug in the cables going to the back of the seat (from the bottom). Reconnected and started right up. If you have no lights on the switch, then it's definitely not heating or cooling. There is a computer at the front lower part of the seat. This is the main ECU. I agree with checking to make sure that got plugged back in, as well as verifying the 3 plugs going to the rear of the seat are all plugged in. There are connectors that allow you to disconnect the wires to separate the seat parts. My techstream code was for a seat sensor rather the seat ECU all together, but disabled it all the same. I will say that in my research before I figured out the sensor was unplugged, there has been some history to the seat ECU failing in the passenger seat. There are at least 2 threads on MUD about it.

Here's the better one:

Seat Heater Crisis /A Critical Accesory

The seat heater abruptly quit yesterday on our 2015. It's the driver's side and my wife's daily driver...and it's winter, so it's up there on her priority of things for me to fix. First indicator was the orange LED next to the control knob was not lit up like the others. So.... I'm looking for...

forum.ih8mud.com

The LX ECUs are pretty rare and expensive. The LSs from the same time had a very similar system and the ECU looks nearly identical even though parts numbers are different. I toyed with the idea of ordering a LS seat control to replace mine when I thought it was out. They go for $40-$60 rather than $400 on eBay.

Also, it isn't hard to remove/check the seat ecu. Just 4 bolts and you can rock the seat back towards the second row and will have full access to the underside.

 

[highfructose]

The seat ventilation on my lx570 sucks. If you’re sweating you can feel it, but otherwise it’s too subtle.

i liken it to the cameras on the front and side...the tech for air conditioned seats and cameras around the front and sides of the cars, while incredibly popular now, was just edging into the market when these cars were developed...so Toyota went “conservative” on both.

they probably didn’t want to spend too much on the camera systems in case they didn’t end up being a major selling point...and they didn’t want to go too nuts on the seat coolers in case people were irritated by the extra fan noise of a powerful seat cooler.

I put a decent little air conditioned seat cover in my driver seat and don’t even use the stock stuff. It doesn’t look as dignified as the stock seat with no cover...but I view the lx as a land cruiser/utility vehicle first...and a luxury “fah nice” vehicle second.

 

[supercarrera]

@Grumvee were you able to get your seat heater working? I'm having the same problem as you had with yours. This switch light doesn't come on and there's no climate function in the passenger seat.

I hooked up Techstream and it can't connect to the climate ECU either. It can connect to the driver side but not passenger.

 

[lx200inAR]

Sounds like that ECU may be blown. There are a few threads on the ECU having a fault, and I believe they were all for the passenger seat. In one thread the guy took apart the ECU and there were some burn marks on the board I think.

Edit: just realized I had already mentioned this in this thread and provided link above to the thread with the dismantled ecu.

 

[Grumvee]

@supercarrera Nope, I haven't got mine working. My next step was going to replace the switch.

It's been back burner for quite a while, but we head up to the Sierras every other weekend for skiing. My wife is usually in the passenger seat, and that's the only one that's not working. Needless to say, she would really like the heat in the seat for these winter excursions

Maybe I'll try Techstream to see if I get the same results you do.

 

[Grumvee]

Problem solved!

Again, big shout out to @turbotwo for his awesome writeup and fix.

 

[Igoteyedeas]

Bought a ’08 LX570 recently, and the front passenger see wasn’t working, including no light when you turn on the switch. This was the first thing I tried and it was a success! Used an LS unit from eBay.

The board I swapped out looked totally fine, so not sure if I might be able to recover it as a backup. Either way, inclined to buy another unit to keep on hand.

Thanks Mud, you saved me a ton of head scratching!