Chrysler Repair: heated seats follow-up, heat element, aluminum block

Question
Hi Roland, it's Greg again:) I looked at the text in the '04 manual you sent you sent me of the seats' operation. Thank you, it shed some more light.  I do not have the bcm circuitry at this point.  All I have are the seats including memory module.  I went to the junk yard and got an appropriate male pigtail for each seat and connected the two color-code correct.  This heated-seats project only has a wire harness from the '96 to work with so far.  Truthfully tho, I have an excellent 700CCA battery with a charger on it energizing this whole setup at 13.5VDC. Eventually the plan is to get the next gen power train (wire harness too, of coarse), since they fit similarly. Younger motor w/less miles, more HP, lighter weight aluminum block...it's all +++.  For now I am still waiting to score the rear-end collision donor vehicle.  

Neither seat is working fully. Passenger: absolutely no LED illumination or heat; motor seat adj and heat-switch illum are fine.  Driver: heat will warm infinitely only to perhaps 80-F AND if you tap any motor adj within 10 seconds (crazy?lol); motor seat adj, heat-switch illum AND motorized seat adj MEMORY all work fine.  Do you still feel the seats' heat will operate without the bcm?  I learned there is a code-reader for the heated portion of the seats, but it's not in the budget.  By disconnecting the power supply to the memory module, do the error codes erase?

I am considering plan B: to just give the seats toggle-switched 12VDC-14.4VDC and a rheostat adjusted to preferred comfort.  But this is not the same as thermistor-intermittent unrestricted voltage.  Do you have an opinion or fact on the effects this alternate may have on the lifespan of the carbon fiber heat element?  If all this steps too far out of your service realm, I understand and appreciate your time one way or the other.  Thanks again, Greg

Answer
Hi Greg,
The nominal operating voltage for the seat heaters is 5V so I would be cautious about starting out with 12.2-14.4V supply that is manually controlled for fear of burning out the heating elements. I do believe that the pci bus wire at the memory module plug could be connected to a diagnostic readout box that is capable of receiving messages about the heated seat system (probably meaning a more sophisticated box than a simple engine/trans fault OBD-II code reader) because the pci bus is the wire that the reader needs to get the coded problem info out of the module. The body diagnostic troubleshoot manual for the '04 LH body does list about a 6 heated seat fault codes which if you could readout would give you a diagnosis of whether the problem with each seat is the switch, the heater circuit, or the thermistor being out of range. But I would suspect that because you have the two seats there to compare you might be well able to figure out what is wrong withe each, without going to the hassle/cost of a diagnostic box and then wiring to it.
Roland
PS Thanks for the rating/nomination. Much appreciated.