BMW Repair: 2001 325i seat heater, cold weather package, electrical diagrams

Question
QUESTION: I have a 2001 325i with a cold weather package.  My driver's side seat heater is not functioning correctly.  It seems to work only when the car is fully warmed up.  When it is not functioning it will turn on briefly (~<1 sec to 5 sec) and then shut off.  The passenger side works fine.  Any thoughts?

ANSWER: Nothing in the system should be impacted if the car is warmed up or not

You say it seems to work when it is warmed up.  What does it do when it is and isn't warmed up?

You say it turns on briefly then shuts off.  How do you tell it goes on/off that quickly?  Lighted switch?



---------- FOLLOW-UP ----------

QUESTION: I didn't think that being warmed up or not would effect it but that seems to be the case.  

Like I said if I press the button for the heated seats there are 3 lights that light up(it has a low, med., and high setting).  They will illuminate briefly and then shut off again.  I was thinking that there was some sort of cut-off in the line (i.e. overheat shut-off) but I am not sure.  I don't have access to any electrical diagrams.

Answer
No overheat sensor or circuit breaker on these.  The heating module in the seat base is a weak link...it's essentially a long filament that gets bent every time you sit on it.

There is a connector under the seat for the heater.  I'd suggest (if you have the capability) you check at the seat side of the connector for continuity (and if good, have someone sit in the seat and try it again), and on the car side of the connector for power.  If there's no power going to it, then check switches, etc.