Tough to say. The element might be burned out.
I am in the process of installing some. The butt heater in the cadillac seats have a temp sensor built in. None of the others do.
If you locate the connectors we can check and compare resistance. I'm sure they are close enough to do comparisions.
If the bonne ones are like the caddy there are 4 elements. Under lower thigh, butt, lower back and upper back. Each is plugged in under the seat to a single relay pack. That is fed hi/low and ignition on from a switch, seperately it is fed fused constant power and ground.
00 Regal GS: All kinds of cool stuff.