dxrohanx

Thank you @Ubermensch ! I will check it out this weekend. Can I ask where you got that schematic?

Kitc2246

Agree continuity check on the seat connectors and heating element continuity would be a good start. Both not working makes the lack of power a bigger suspect. Depending on how it is wired the switch button not lighting is either the lack of power or an open circuit. If you can easily remove or get to the back of the control switch check to see if it has power.

Be careful turning on the ignition with all the seat plugs disconnected. Suspect the heated seat is a separate connector. My son removed his passenger seat one time on a 987.2 to carry a set of wheels and tires. Caused an error that required a tool to reset. Related to the air bags and seat occupancy sensor.

Ubermensch

Agreed that a single failure causing both seats not to work is likely a power supply issue. The PO suggests he's got a good fuse, so it's worth double-checking power is being supplied to the fuse and getting to the other side of it. That said, the OP doesn't know when the seats stopped working from what I understand. So each may have failed independently. My main point is that this may be the simplest circuit in the car so I'd spend my time tracing the current flow in the circuit and not spending time with coding and code readers.

That's a great point about the airbag light! Powering up with the seats unplugged will generate a code. I'd disconnect the battery before disconnecting the seats.

Ubermensch

3366-987.1 WIRING DIAGRAMS.pdf (planet-9.com)