View Full Version : Heated recaro seats(not RS5) wiring
Hi all
I have some new recaro sportster CS seats but haven't installed them yet.
Is there a way to wire the heated seats so that they are still controlled by the center console button which is a 4 position switch bassically.
Not really getting a clear answer from recaro.
Thx
Smac770
09-15-2022, 12:53 PM
The wiring for the heated seats is four wires. Power and ground for the grid, and the two wires for the temp thermistor. The Recaro seats would need to have the same wiring connections and same manner of thermistor (so that the same temp at the seat conveys the same resistance on the circuit so the J519 interprets the electrical characteristics as the correct temp).
Recaro, best I can tell from their website, is an elitist company that thinks end customers shouldn't attempt doing anything themselves. There's no documentation whatsoever of anything. So who knows.
The wiring for the heated seats is four wires. Power and ground for the grid, and the two wires for the temp thermistor. The Recaro seats would need to have the same wiring connections and same manner of thermistor (so that the same temp at the seat conveys the same resistance on the circuit so the J519 interprets the electrical characteristics as the correct temp).
Recaro, best I can tell from their website, is an elitist company that thinks end customers shouldn't attempt doing anything themselves. There's no documentation whatsoever of anything. So who knows.
LoL yeah you're right about recaro. They are not very helpful.
Yet I would assume it to be possible to get the stock controls to work with these seats.
Smac770
09-15-2022, 04:43 PM
How is the Recaro heating controlled out of the box? Do they have their own controls?
How is the Recaro heating controlled out of the box? Do they have their own controls?
Switch on the side. But it's just on/off.
But I figured if somehow it can be wired up so that the seat switch just remains in the on position and the OEM controls do the real controlling.
Smac770
09-15-2022, 06:30 PM
What you'd have to do is figure out if that toggle switch is actually in the path of the actual main power flow, or just a control line to a relay or such. Then backtrack how the seat is getting the power and ground to the heater grid and whether or not it's already plugging into the 6-pin green socket in the floor board, or using some other path. If some other path, you'd have to reroute it back to the green plug on the pins the original seat used. And then you'd have to figure out how to fool the thermistor on the J519 on the two other pins of the 6-pin green socket. I don't know if it'll operate with an open circuit. I forget which way the resistance changes (increase with temp or decrease with temp) with that thermistor. Shunting it rather than locating one into the seat (hell, there may already be one there wired to a relay in the path of the main power; you'd have to ask Recaro if the seat heating has a thermal safety cutoff in case the switch is left on and no one is in the seat) risks what I just referred to, if the heater is on and no one is in the seat. It can all be done; it's very simple electrics, but one cannot commit anything without actual eyes and hands on the actual whatever.
I did get a schematic from recaro.
282294
Smac770
09-17-2022, 05:44 AM
If we reorganize that diagram into the following:
282385
We see that you connect it to term 15 (ignition on) and term 31 (ground) from the car. That connection could very well be inside the seat, pulling from the power and ground connections already made between the seat and the car (if it's a power adjustments seat), or that's a connection you have to make yourself. No idea.
Within the heater circuit, there's a PTC thermistor / thermal fuse (starts low resistance, increases resistance as temperature rises) I presume as a protection mechanism as the circuit seems to otherwise lack fusing on the power source.
There's an NTC thermistor (starts high resistance, decreases resistance as temperature rises) integrated into the seat cushion. I assume this functions by allowing increasing current flow as the resistance decreases until there's sufficient current flow to trip a cutoff relay inside the control module. I don't remember if the thermistor in the Audi heater pad is PTC or NTC. I did measure that stuff once, but I can't find the log these days.
The other complication is the NTC thermistor is connected to the heater grid ground line inside the pad. Audi has 4 pins on the green plug, power and ground to the grid, and the two wires to the thermistor. So there's no second wire from the NTC to connect to the second control line on the green seat plug.
If we reorganize that diagram into the following:
282385
We see that you connect it to term 15 (ignition on) and term 31 (ground) from the car. That connection could very well be inside the seat, pulling from the power and ground connections already made between the seat and the car (if it's a power adjustments seat), or that's a connection you have to make yourself. No idea.
Within the heater circuit, there's a PTC thermistor / thermal fuse (starts low resistance, increases resistance as temperature rises) I presume as a protection mechanism as the circuit seems to otherwise lack fusing on the power source.
There's an NTC thermistor (starts high resistance, decreases resistance as temperature rises) integrated into the seat cushion. I assume this functions by allowing increasing current flow as the resistance decreases until there's sufficient current flow to trip a cutoff relay inside the control module. I don't remember if the thermistor in the Audi heater pad is PTC or NTC. I did measure that stuff once, but I can't find the log these days.
The other complication is the NTC thermistor is connected to the heater grid ground line inside the pad. Audi has 4 pins on the green plug, power and ground to the grid, and the two wires to the thermistor. So there's no second wire from the NTC to connect to the second control line on the green seat plug.
I'll have a look this week when I have some time pull out a seat.
OEM RS5's would have probably made more sense, but wiring those up would probably also be some work since those have more options most of the time.
And the weight reduction would not really be there either.
s vier
09-18-2022, 11:15 AM
If you go from RS5 North American "Sport Seats" to European RS5 Recaros there is fairly direct plug and play for most controls though you actually LOSE one option: the seat memory. You can pull it out from the door and source a blank or non memory unit. The heaters work as they should, upper and lower bolsters are electric and work as well. The only issue is airbag light related. "Passenger Air Bag OFF" and the "AIRBAG" dummy light in the cluster. Both are fixable. The 2 Recaro seats shed 56lbs off collectively from the Sport Seats if I remember correctly. They are essentially Recaro Sportster CS seats with more padding and features. I sat in both before pulling the trigger.
If you go from RS5 North American "Sport Seats" to European RS5 Recaros there is fairly direct plug and play for most controls though you actually LOSE one option: the seat memory. You can pull it out from the door and source a blank or non memory unit. The heaters work as they should, upper and lower bolsters are electric and work as well. The only issue is airbag light related. "Passenger Air Bag OFF" and the "AIRBAG" dummy light in the cluster. Both are fixable. The 2 Recaro seats shed 56lbs off collectively from the Sport Seats if I remember correctly. They are essentially Recaro Sportster CS seats with more padding and features. I sat in both before pulling the trigger.
Those are hard to find these days.
But I have these Recaro's laying around still in the box for a while.