Heated seats not working...need troubleshooting help and advice...

[agfours]

Need some help diagnosing a heated seat problem...Vehicle info: 1985 3.2 M491 Cabriolet.

Issue: both seats are not heating, but shop says they have checked all 'switches and electrics' stating that the problem is the heating element.

However, based on my layman's review of the wiring diagram, the seats seem to be on independent circuits. This tells me that they may be wired in parallel...(can anyone confirm?) Assuming this is true, my assumption here is that there is some more systemic failure (central point like a ground, common relay, switch), but again, the shop is suggesting that the 'switches' and electrics have been checked, and it is the element....(in both seats? granted, possible. These have not worked while the car was in my possession, so can't confirm if they failed independently or together.)

First question - are there any other common points of failure for the heating elements not listed here? i.e. common relay?
1. Heated seat relay for each seat...(not common, but let's assume wired in series)
2. Power / Ground
3. Rotory switch
4. fuse

Second question - let's assume all of the above checks out. Are these elements wired in series, wherein one element would cause failure of all 4? (2 per seat).

Third question - can the elements be replaced without ripping the upholstery apart, or is this a seat rebuild?

Fourth question - one suggestion was to have aftermarket heated seats put on the car in place alongside the original equipment, meaning that there would be an additional aftermarket switch placed on the console. Not a fan of this as it would be non-original to the car, and would have questions about properly wiring this due to loads on the electrical, etc. and the possible perception of aftermarket equipment devaluing the car....should I be concerned? It's a daily driver, but I'm not a fan of these kinds of approaches...estimate in the $600 range. valid?

Fifth question - any estimates on how much this would cost to fix if the OE heating element(s) needs to be replaced - (based on an original equipment replacement/fix, not an aftermarket approach).

Thanks!!

[vince_aust]

had the same problem on my 87. removed seats, checked switches and did a continuity check on heater element - found open circuit (simple resistance check with ohm meter). Looked at what was required to access element (to repair) and it appeared the seat needed to be completely removed of its leather. Decided project could be deferred as I live in a mild climate.

Each seat is an independent circuit