5Series.net - Forums - 2008 535XiT - rear seat warmers not working

Hi guys,

I've got a new to me 2008 BMW 535xi Touring (1st BMW as well) that I'm trying to fully sort. I'll post a separate topic for each issue with the touring specific questions here and the general issues in the E60 discussion forum. Car currently has 3 known issues (steering wheel heater, lane departure malfunction, and the rear seat heaters) - This is specifically about the rear seat heaters:

Symptoms:

Both switches will just light up momentarily and then shut off.

Things done:

New OE battery w/ registration at dealership. (Lead Acid as per VIN)
All fuses good.
Car was idling with a 15 - 15.3V reading.
Found and fixed a 0.4V votlage drop from front battery to front boost connections by cleaning and using dielectric grease on all reachable connections.
Can't find any rear seat heater codes using a C310+ reader.

Questions:

Any recommended diagnostic resources? I've got INPA but awaiting a cable to connect to the car, but I've never used the software and have no idea what if any service or troubleshooting info in might have.
realoem.com shows that there should be a module in the "spare tire" well, and possibly a single relay to check. Was hoping someone may have had a similar issue with a successful resolution before I randomly start trying fixes.
I mentioned the steering wheel heater and lane departure just on the very outside change there was some correlation. :)

Thanks in advance for any and all help! I promise whatever solution I find I'll make sure to update with a resolution.

Rabin