I just bought a 95 Max SE with heated seats. The driver side button is definitely broken but the passenger button looks ok and lights up when you turn it on. But the passenger seat doesn't get warm. Could this be because the driver side button is broken or is it something internal in the seat?

 

I have a related question. Both my heated seats work great, but the bulbs don't light up. And is there supposed to be some sort of illumination for them while they are off too?

 

The actual elements in the seats can be burned out. Aftermarket ones can be bought and installed. Check all connections under the seat, you might get lucky.

When they are off, there is no illumination.

 

As he said above, check all the connectors. Otherwise something is broken with the actual seats. The light for my driver seat doesn't turn on, but both seats work well. Also... keep in mind, im pretty sure, u have to be sitting on the seat before it gets warm (correct me if im wrong) I think they dont heat up if there is no weight on the seat... also my seat takes a good 5-10 minutes to warm up when sitting on them. So sit down in the seat and give it some time, if you have not done so already.

 

^^^No you don't have to be sitting on the seat LOL.

And personally my switch was bad when I had this issue, which is VERY uncommon. I was more naieve when it happened and didn't try to take it apart.
check for power first both into the switch, and out when its turned on with a test light/multimeter, also you can check the wiring to the seat itself.