Heated seat retrofit with pictures

[cooluserid]

Great thread. I have three questions:

1. Where did you get matching OEM connectors? What are the part numbers?
2. Your test with potentiometer showed >6kOhm thermistor resistance to start heating. Was it with high or low settings (two or one LED on the control switch)? Did you measure the other one?
3. Why did you choose 50K and 10Kor 30K?

50KOhm thermistor will be at 6KOhm at 75C or 167F
30KOhm thermistor will be at 6KOhm at 60C or 140F
10KOhm thermistor will be at 6KOhm at 38C or 100F

[nigwhyrito]

Hi cool
okay answers
1. part numbers and parts check this 2 page thread read it all....http://www.xoutpost.com/bmw-sav-foru...-8-owners.html
2. I think that was on high all leds lit.
3. to be honest I hated math so tons of googling found people that used that thermistor on bmws.
Also i was trying to match or stay near bmw reccomended temperatures.
i dont have it on this pc but if you go to the wds site and look up rear seat heating it will show you the temps the elements are supposed to be at for stage 1 and stage 2. rear seats are dual stage. front seats are 3 stages.

hope that answers your question if not i will post the wds guide i used.

1 other thing cool remember thermistor is only needed if you have old heating elements that are 1.. only 1 stage meaning get hot or turn off.
2. only 2 wires.

Most newer elements are 3 wires and already have the themistor in them.

[aimtimes100]

ok this was only done for the rear seats, does anyone happen to know how the process would be if you wanted to add heated seats to the driver and passengers seat?

[bmwman528e]

It would 100x easier just to run the aftermarket heaters on their own wiring and circuits and then just use the Factory X5 Heated Seat button and get it to work with the new wiring.

[nigwhyrito]

Originally Posted by bmwman528e

It would 100x easier just to run the aftermarket heaters on their own wiring and circuits and then just use the Factory X5 Heated Seat button and get it to work with the new wiring.

hmmm bmwman528e - Curious were you talking to me. Reason I ask is because thats what I did. My aftermarkets were single stage heaters. The bmw switch and electronics are for a dual stage heater. So without the thermistor the BMW switch would not work. My aftermarket kit was for kia sorento that I crashed a long time ago. So when you say 100x easier you must have meant for me to buy another aftermarket kit. That 1 already was dual stage heaters. 2 Made for bmw 3. spend money that I didnt have to spend ? Just confused by the last post thats all.

[nigwhyrito]

Originally Posted by aimtimes100

ok this was only done for the rear seats, does anyone happen to know how the process would be if you wanted to add heated seats to the driver and passengers seat?

Aimtimes are you still looking for an answer to this question if so I can give you tons of DIY articles for this. The front seats is documented even with video all over the net. The rear seats hardly any documentation.you have to buy the then switch console with the heated seat buttons.you have to jumper 2 wires, you have to add relays. you have to remove the leather and affix the sensor..let me know if you need a guide for the front seats google turned up so many searches when i was starting.

[cooluserid]

bmwman528e
OEM system is safer then retrofit:
It shuts down when thermistor is too hot or disconnected,
It regulates heating by using thermistor signal VS klixon in majority of retrofits;
Most of all it looks better. It is much easier to install then retrofit. Extra cost is $100-$150 (OEM switches and connectors). It is approximately 15 minutes to install OEM switches in the center console and relay in the trunk.

nigwhyrito: I repeated test that was described in post #25 and found that threshold is 4.5kOm for LOW (one LED on) and 3.5kOm for HIGH (two LED).

I selected 10kOm thermistor from DigiKey. It regulates heaters at 100F (LOW) and 110F HIGH. My heating pads (Carbon mesh from EBay) have build in klixons set for 140F.

nigwhyrito:I think your 100kOm thermistor will not regulate. Your heater is regulated by klixon (thermal protection switch). It is good to keep klixon for protection and not to use continuously. Klixons do fail and then heater will be running continuously without regulation.

[nigwhyrito]

Thanks cool for the concern but I actually removed the klixons or as my dad called temp switches. I didnt like the fact the seats were not as hot. It kept kicking in to fast. My thermistor in the seat lements are working fine. I tested with a temp probe 3 distinct different temps 0ff high and low.. crap I forgot what they were but they were the same as what bmw posted. Also you said 100kΩ, i thought I purchased 2: 50kΩ.
50kΩ per circuit. I thought the seat heaters left and right were considered 2 different circuits. So are you combining total resistance when both are on at same time?

[aimtimes100]

Originally Posted by nigwhyrito

Aimtimes are you still looking for an answer to this question if so I can give you tons of DIY articles for this. The front seats is documented even with video all over the net. The rear seats hardly any documentation.you have to buy the then switch console with the heated seat buttons.you have to jumper 2 wires, you have to add relays. you have to remove the leather and affix the sensor..let me know if you need a guide for the front seats google turned up so many searches when i was starting.

thank you for the feedback, but after seeing a few DIYs all requireing the removal of the seat and seat cover, i dont think ill be doing this one

[Helmuth]

Originally Posted by nigwhyrito

Aimtimes are you still looking for an answer to this question if so I can give you tons of DIY articles for this. The front seats is documented even with video all over the net. The rear seats hardly any documentation.you have to buy the then switch console with the heated seat buttons.you have to jumper 2 wires, you have to add relays. you have to remove the leather and affix the sensor..let me know if you need a guide for the front seats google turned up so many searches when i was starting.

Hi nigwhyrito,

would be VERY interested in a guide for dummies for heated rear seats. I already have the console with the 2 switches, I have the heated backseat with the original plugs coming out of the seat but I have no cabling below the seat and maybe no relay (no idea where that has to be).

Thank you

Helmuth