Seat heat fades out (1 Viewer)

[pdot]

My seat heaters get warm when first starting the car, but inevitably fade out within 10-30 min. But maybe another 30 min later, they'll resume warming.

Most of my testing is with the driver seat obviously, but both exhibit the fade. It's not the switches since I've replaced those.

I've been driving around with a multimeter connected in place of the switch. When the heat fades, the current goes from around 2.5 amps to 0. I've stopped the car in this state and measured the resistance through the "HI" path to ground and it's open! But when I keep checking it, it eventually returns to a normal ~5 ohms after 10-15 min.

Is there a component of the circuit (like a thermistor or temp sensor) which would cause this? Or is this simply a symptom of a failing heater element?

 

[novamarc]

Curious about this myself as I experience the same thing in my 06 LX. I always just figured it was a safety feature considering my 20 Tacoma did the same thing since day 1 until I sold it last year.

 

[Exiled]

This is interesting, and will watch your progress in root-causing this. I have two 1999s and one exhibits the exact same symptoms you describe, and the other one just keeps getting hotter until you have to turn it off or burn your thighs!