$28 seat heat pad replacement DIY

[Turbo_Bimmer]

Originally Posted by stewey

Nice write up! I'm planning to do this myself. Just curious, how did you determine the specs for the factory warmers? Or the dorman ones for that matter (I don't see them on their site).

Thanks,
I measured the resistance of the bottom heater of the passenger seat (working one). Since the Dorman one has lower resistance, I had to add the power resistor to reduce the voltage at the heater.

Just a note on the value of the resistor. With the 0.47R the heating was too much. I then switched to a 0.68R resistor. In my case the pad is directly under the leather, maybe if someone installs it under the insulation the 0.47R would be ok. Anyways, changing the resistor is not a big jog.

Search for 641-203 in EBay and you will find a vendor.
Good luck.