Both front seat heaters quit working?

Hello chevy1999tahoe

Try unplugging the connector use a volt meter on it, if there is voltage at the connector, the heating element is No good.

Hello chevy1999tahoe

Lets start from the beginning.
My understanding of the first post was that the driver side heated seat is not working and you have power going to it.
What happens when you push on the button (switch) for the driver heated seat?
The driver and passenger side heated elements share the fuse 20A in the fuse box. If only the driver side is not working, then the fuse is o.K. You can try to unplug the connector to the heated element under the driver seat and while activating it (pushing on the button) check with test light if there is power at the connector.
If there is no power, the problem is with the switch or the wire from the switch to the connector is broken.
If there is power, the heated element is defective and will need to be replaced.

Disconnect the body harness to seat harness connectors at the rear of the front seats. Check for heat damage, or otherwise a poor connection. At this point a wiring repair will be needed, with new terminals and connector body. If you find nothing at the seat to body connectors, and it has drivers memory seat, check the connections at the memory seat module.

Hello chevy1999tahoe _
good job

Remove the connector to the switch with engine off, check continuity on the switch(where the black and purple wire connect)
if you get infinite resistance, replace the switch.

The fact that it is experiencing concern with both seats, I would suspect a connection issue at either the driver/passenger seat to body harness connector, or the seat module. There is no relay, nor an independent seat heater module. Both seats share a common power, and a common ground through the memory seat module. The way the system works, is the heated seat switches are wired to the respective door modules, and the door modules send bus messages to the seat module for operation. Open/high resistance elements, could cause this concern. But you would have to have at least one on each seat.

Hello _

Tell me everything you have done then I will know what need to be done.

You need a new heater element on the driver side. If there is power to the element but it does not work.
Replacing the element will solve the problem.

Yes, replace them and that should take care of the problem

Check the circuit breaker...