Guidance on Heated Seat Retrofit

[jrgatfh]

Hey Guys,

I've slowly been doing research and acquiring parts to retrofit heated seats to my 2005 coupe.

So far I've sourced the following:

1. Center control panel with heated seat buttons (eBay)
2. Wiring Harness from seats to dash Part # 61-11-6-930-656
3. Wiring Harness from dash to fuse panel
   1. I have Part # 61-11-6-902-951, but I'm not sure if this is the correct harness because my research also shows me Part # 61-11-6-930-660. Part # 61-11-6-930-660 is still available and relatively cheap so i might just buy it just in case.
4. The hardest parts to source have been the heating element themselves which are sewn into the seat covers and not available individually. It appears my options are as follows and I wanted to get your opinions on this:
   1. Buy used seats from a junk yard and cut the heated seat elements out of them and re-use them.
      1. Will heating elements from a sedan or non-M car work?
      2. If they do I'm a little nervous to go through all the work of having used heating elements sewn into my existing seat covers only to fail soon after. Am I overthinking this?
   2. It seems like E39 heating elements might be a possibility, and they can still be purchased new at the moment. I've seen several threads mention this possibility but none of them state clear if they work or whether they're plug-and-play or need to be modified.
      1. I like the idea of new heating elements but rather not have to modify anything.
      2. It seems like the E39 only has heating elements for the seat bottom and not the seat back. I'm pretty sure the E46 has heating elements on the seat back and seat bottom.

I appreciate any advice/insight/guidance you guys can give. Hopefully it helps other forum members as well.

Cheers.

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Update 1/11/22:

In case anyone else wanted to go down this road the E39 does have heat elements on the seat back and the Part #’s for the E39 heating elements are as follows:

Heating Element for Seat Bottom: 52108203258 - Currently available from TMS for $99.11/ea
Heating Element for Seat Back: 52108253116 - Currently available from TMS for $77.30/ea

[dl.m3]

From my experience fitting heated seats into my Recaros. Cutting out stock heating elements is a huge huge pain and very likely you'll tear something.

E39 elements can fit with some modification of the harness (or you can cut and solder). But the issue is how you can insert the heater element over the stitched cushions in the stock seats. When the stock seats are made the heater elements are inserted first and then everything gets stitched together.

E39 elements have a backrest portion as well, I dont have the part# handy but its on realOEM.

Your best bet is to source stock heated seats and avoid all this headache. Good luck.

Sent from my HD1905 using Tapatalk

[jrgatfh]

From my experience fitting heated seats into my Recaros. Cutting out stock heating elements is a huge huge pain and very likely you'll tear something.

E39 elements can fit with some modification of the harness (or you can cut and solder). But the issue is how you can insert the heater element over the stitched cushions in the stock seats. When the stock seats are made the heater elements are inserted first and then everything gets stitched together.

E39 elements have a backrest portion as well, I dont have the part# handy but its on realOEM.

Your best bet is to source stock heated seats and avoid all this headache. Good luck.

Sent from my HD1905 using Tapatalk

Thanks for the insight. I have an interior guy I’ve worked with before on other cars who I trust so I’m not worried about stitching in the heating element. I just dont know if I should go with used E46 elements or the E39 units.

Edit: added E39 heating element part #’s to the OP.

[old///MFanatic]

I'm pretty sure the E46 has heating elements on the seat back and seat bottom.

Correct, factory E46 M3 seats have heated bottoms and back.

[nextelbuddy]

i have retrofitted he elements into a few cars including my own. i always found junk e46 heated seats and carefully used a razor blade and cut out (using a razor to cut the thread to separate the pads from the covers.) the seat elements from the old seats and then gave the to an upholster with my seat covers and had them sew them together.

the e39 seat elements while they can be purchased separately, they do have the same connectors that slip into the yellow seat harness under the seat. the main difference is that the e39 bottom seat elements do not have the THIGH support portion of heated seat elements like the e46 and e53 seats do. they closer to the e46 comfort heated set pads that do not have thigh support pads.

you dont really need to wire anything from the switch center to the fuse box, if you have a switch center then it is already wired to the fuse box, you just have to wire from the heated seats to the switch center and then ground each heated seat to a grounding block in the chassis under the carpet near each seat.

you can get away with heated seat pads from e46 non M Sport seats since they have the thigh support but the back seat pads have a slightly different shape for the M3 seat covers compared to the sport seat pads. its not terrible and you wont even notice when the heat is working. its just where the seams match up on the elements to the seat covers really but once they are sewn on its fine.

[Brian129]

i have retrofitted he elements into a few cars including my own. i always found junk e46 heated seats and carefully used a razor blade and cut out (using a razor to cut the thread to separate the pads from the covers.) the seat elements from the old seats and then gave the to an upholster with my seat covers and had them sew them together.

the e39 seat elements while they can be purchased separately, they do have the same connectors that slip into the yellow seat harness under the seat. the main difference is that the e39 bottom seat elements do not have the THIGH support portion of heated seat elements like the e46 and e53 seats do. they closer to the e46 comfort heated set pads that do not have thigh support pads.

you dont really need to wire anything from the switch center to the fuse box, if you have a switch center then it is already wired to the fuse box, you just have to wire from the heated seats to the switch center and then ground each heated seat to a grounding block in the chassis under the carpet near each seat.

you can get away with heated seat pads from e46 non M Sport seats since they have the thigh support but the back seat pads have a slightly different shape for the M3 seat covers compared to the sport seat pads. its not terrible and you wont even notice when the heat is working. its just where the seams match up on the elements to the seat covers really but once they are sewn on its fine.

Hey Shawn,

I'm swapping the seats in my M3, and actually found a set with heated seats from the factory.
I picked up the center switch with heated buttons on, and have a set of cut connectors from the center switch and each seat.
I found I was only missing 4 wires at the center switch( pin 1,13,20,and 21) so I have added them in, I also see there are three wires at each seat, seemingly power, ground, and a signal.

in this post ( https://www.e46fanatics.com/threads/...rofit.1271283/ ) it shows there are two runs to the fuse box, that’s what you are saying I won’t need. Can I leave the KCan line out too? Or do I need to feed that back to KCan?

[nextelbuddy]

Hey Shawn,

I'm swapping the seats in my M3, and actually found a set with heated seats from the factory.
I picked up the center switch with heated buttons on, and have a set of cut connectors from the center switch and each seat.
I found I was only missing 4 wires at the center switch( pin 1,13,20,and 21) so I have added them in, I also see there are three wires at each seat, seemingly power, ground, and a signal.

in this post ( https://www.e46fanatics.com/threads/...rofit.1271283/ ) it shows there are two runs to the fuse box, that’s what you are saying I won’t need. Can I leave the KCan line out too? Or do I need to feed that back to KCan?

If your car already had a switch center then you don't have to run anything to the fuse box or K line. That diy on E46 fanatics was showing what you have to do if you don't have a switch center and just have the large single buttons instead.

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[Leafsrule531]

Thanks so much for all the information everyone has provided here. I’m looking to the tackle the same job in my m3 and was wondering if anyone could help or provide more info on the wiring. I already have the switch center so based on my understanding, I’m just swapping out my current switch center with the one I bought which has the heated seats buttons and I won’t have to tap into the fuse box. I know there’s a guide on e46fanatics but it doesn’t help with the wiring for someone who already had a switch center. Would really appreciate any help or advice if anyone could help with the wiring from the seat harness to the new switch center!

[nextelbuddy]

Not sure which retrofit guide you're looking at on E46 fanatics but the one I followed which is this one

https://www.e46fanatics.com/threads/diy-non-heated-to-heated-seat-retrofit-lots-of-pics.341242/

Work for me just fine.

Yes, it does include instructions for people who do not have a switch center, but if you already have a switch center then you just skip that portion and you move on to the portion where he shows how to wire the seats to the switch center.

It's pretty detailed and should have everything you need. If you're not understanding it, go back and read through it a little bit more slowly. It doesn't get more cut and dry than that one

[Leafsrule531]

Thanks. You were right - reading it slowly and looking at the actual wires made a lot more sense especially now that I know that I can ignore the whole fuse box section.

Appreciate the guidance!