Hello, read here
https://www.omegaowners.com/forum/index.php?topic=149084.0
and other places too, that FL front seat "heaters aren't known for their durability"...
So mine are broken, too, 2001 FL (Elegance) Tried to check the wiring a bit...
So, five Connectors, below is what I think?
Yellow=Side Air Bag
White or Light Gray with Brown and Blue wires=Seat Belt Tensioner
Grey with Brown and Red=Electricity to Standard Seat up&down control motor
Green with Black having Yellow stripe and another Black having Green stripe indicates 11kOhm resistance. Is this the 'heating controller' unit (PTC/NTC) resistor TB discussed in link above? Temperature was +10 degrees Celsius.
Black with Black and Brown, resistance here is infinity so if this is the heater units (in series) one of them certainly broken.
If it is as described above:
1. What should be the resistance of the heater unit when ok?
2. How does the control work, is it On/Off according to temp measurement (1-5) or are there resistors somewhere which gives 5 different Voltages?
3. What is typical place to find failure if heater unit is broken?
Sadly, you can't test the seat heater elements like that. There is an electronic control unit in the seat itself - K183 and K184 in the circuit diagrams.
The thin Black/Yellow wire is the main on/off from the dashboard switch.
The Black/Green wire is an analogue resistance from the dashboard switch which presumably controls how hot the element gets.
The thick black wire is the Main Power (12V from fuse F15)
The thick Brown wire is Ground/Chassis/Earth/Whatever you want to call it.
There is one connection from K183/184 to the heater element +ve, and a ground (to the brown wire)
There is one connection from K183/184 to the thermistor, and a ground (to the brown wire)
So to test the element you're going to have to locate K183/184, and unplug them. I'd expect the element resistance to be less than a few ohms.
I suspect K183/184 may look like relays - the terminals on the circuit diagrams are labelled 15 (12 V from Fuse F15), 31 (ground), 86E (dash on/off), P (dash temperature control), T (Thermistor), H (Heat Pad)