I have a 2001 CLK 320 Cabrio and have been doing some research on converting stock CLK seats to heated. For the past several months, on and off, I have been speaking to mechanics at dealerships and Indy shops and have come to a dead end. Furthermore, there has been some misinformation and some truths, but to no end.

First, the CLK 320 does not have the heating elements in the passenger side of a non-heated seat as many have said. I pulled my seat and what they think is a heating element is actually a sensor pad for children that turns the airbag off on that side. Secondly, I did find two extra plugs on the wiring harness behind the climate control bezel that were taped back; they plug into the switches for the heated seats and the head light washer switch. I actually found a heated switch gang with head light washer on ebay for around $65; it included the laminated wood bezel. After installing the switches the two heated seat switches illuminated properly; down once for one LED down a second time for two LED. Done in the reverse and it turns off. If I would leave it on two LED the timing function would shut it down to one LED after a period of time. That much works.

I did pull the sills from the door and looked through the loom and found a few unused plugs, but don't know what to pull off to power the elements. On that topic, I did find out that the MB elements do get nice and hot, but have been known to fail, crack and burn out. There are aftermarket elements that are made of carbon fiber and although they do not get as hot they will not fail if random areas break over time.

Back to the loom that runs under the sills. If someone can point me in the right direction and or post some photos of what there loom looks like under their sills (those of you with heated factory seats) I think I can get this to work with the factory switches. I doubt there is anything else other than connecting the heating elements to the loom under the sills. The four pronged plug that I connected to the heated seat switches had three small gauge wires (approx. 16) and one large gauge (approx. 12). That tells me that that plug does regulate the current for the element.

Any help would be appreciated and if I do get it working I would be happy to post a full tutorial on doing this. I know it would be used by many and the parts are cheap. Aftermarket carbon fiber elements are about $90 a seat and the bezel and switches are only $65 on eBay.

SirSwift93

 

its very easy to do so here is the list of what you need:

1. the woodgrain piece that goes around the ac control unit
2. the seat heater switches
3. the heating pads

this is how you do it:

1. take off the woodgrain and replace it with the new one that has the 7 holes on the top.
2. when you take your switches out you will notice that they are sitting on a plastic bracket, pull them out of that and put them on the new brackect that came with the heated seat switces, they will plug right in.
3. the connect the wires to them.
4. look for a black socket with 4 think wires connected to it, just look back there it is there, mercedes pre ran all the wires weather the car came with that option or not so the wires are back there
5. once you located the black socket with the thicker wires plug it to the side of the heated switches you will see it there on the side of the heated seat switch racket.
6. put everything back in its place.

7. now you have to take the bottom seat cover off and put the heating pads inbetween the foam part and the cover and run the wire from inside the foam where all the other wires (airbag sensor, motor wire) are ran to the bottom of the seats.

8. put the seat cover back
9. plug the heater pad wiresocket to the socket under the seat.

10. sit on the seat, click the switches and enjoy a warm bottom.

p.s. in my experience the relay and the fuses are also preinstalled on the sam unite in the fuse box inside the hood.

hope this helped.

 

oh wow i had no idea you can just do it like that, i always wanted heated seats!

 

very simple to do. i should really start charging for all these DIY. haha

 

lol u should.. btw do i just order heating mats from the dealer?

 

Relay? Which? Maybe the relay is the problem in my car, because elements and fuse 25/41 is confirmed ok. And switches light up as they should.

 

VIP

I completed the steps you lusted up through step 8. I have been trying to get past that step for some time now and hope I didn't just overlook the the ports under the seats. I looked under the seats and saw where the airbag sensor plugs in but did not see an open port that a heat mat could be plugged in. Is the plug in the loom beneath the sill plate? Is it under the rug beneath the seat?

If anyone has purchased an aftermarket heat mat can you please tell me where you purchased it and if your happy with your choice?

Thanks

 

Wow ur alrdy going it at? Good luck man I wish u the best of luck. Hope u will be able to provide us with pics after ur done I'm sure ash(VIP) will get back to u soon to help complete the project. He's helped me thru numerous DIY projects and his knowledge for our cars is insane

 

the cable that you are looking for is underneath the carpet inside the plastic wire tunnel.

 

Thanks VIP. Do I have to remove the seat to get at it? Is there a plug that connects directly to the oem heat pad? If not I just might get the carbon fiber mat. Is there a heat mat on the back of our chairs too or just the bottom?

Any tips on getting the seat cover off?

Thanks

SirSwift93

 

its easier if you take the seat off, its really easy just four torx screws. as for the pads i belive they are only on the bottom but i dont know exactly so someone with more experiese perhaps should chime in.

 

Does anyone happen to know if the w209 CLK is a similar job (MY 2004, CLK500)?