So today I was driving and smelled a burning smell. I looked in the back driver seat was smoking. Any idea what it could be. Is it the battery?

 

Why not remove the seat bottom and investigate? There are several Youtube videos on how to do it, very easy. Also, plug in the OBD port for codes. If it's an essential system part like the battery, it'll show a code.

 

Sounds like you have an exposed wire.

 

Wouldn’t an exposed wire still smoke if the car is off?

 

No, if there is no power running through it. For instance it could be a wire for the heated seat. Even if the heat switch is on the seat won't heat up if the car is shut off.

 

It seems that the owner isn't familiar with the basics of electrical workings. Not a criticism but an observation. Suggest he have a mechanic look at it.

 

So I found water under the passenger cushion. I’m assuming that may have caused and arc in the wires but I didn’t see any burnt wires. I started it up with the seats out and no smoke. The fuel pump access is the culprit I’m guessing. Anywhere else water may be coming from in that area?

 

It is probably from the sunroof. I am not mistaken, there is sunroof drainage hose on that side. It could be clogged, damaged, disconnected etc.

 

Do you know what area it would be in?

 

I am sorry, I take that back. However there is AC drainage under that seat. There is a picture of the drain visible from underneath - https://www.clublexus.com/forums/ls-...ml#post6415793

 

Unlikely, the fuel pump access is above and protected by the fuel tank. No way for road water to enter. You said the smoke was on the driver side. That ac tube link is for the front of cabin. Any passengers that could have spilled water recently? Leave the seat out for a week or so and check for water after every drive. If you had the seat out and unplugged, it won't make the seat heater smoke. You could have also blown a fuse, no more smoke then either. Several fuse locations in this car including the trunk. Do you have rear seat heater or any options like tilt or massage? Test them to see if they work.

 

I found out the issue!!!!! So the sunroof drain I think is clogged and it was leaking water somehow onto the rear defroster wire. The rear defroster wire is pretty burned up. How do I clean sunroof drain hose?

 

Weed wacker line, you can get a roll for like $5 or so and it is easy to feed through every drain

 

Do I feed it thru the top or bottom?

 

I'm not sure, but I would probably remove it from the wacker first.