The passenger's side works fine and on the driver's side it does not. I checked the fuse and it's okay. The Left button lights on but no heat, please what else can I check ??? And my lighter too...

 

heater or wiring

 

Quick test of switch/power to switch: With car running, turn off radio and climate control (needs to be quiet). Press the switch for the heated seats. You should hear a "click" when you depress the swtich - it's the relay in the dash. If you hear the click, something after the switch (relay, actual heater, wiring to the seat, etc) is fockedup. If you don't hear the click, something before the switch is messed up. Given the switch lights up, it's probably something after.