Heated Seats Retrofit

Faheem

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I bought sport seats for the car several months ago and swapped the wiring over from my old seats to get the up/down and forward/backward functions to work.

However as they're heated i thought it's time to buy the adapters from BMW and put the original connectors back on to the seat.

I received the connectors yesterday and am tackling this today. It seems straight forward but Im a little confused as I'm unsure why both looms for the seat have a section chopped off, I've attached a picture of all the connectors on the drivers side loom followed by an image of the chopped of wires.

Any ideas what should be there?
IMG_20171007_145445.jpg

IMG_20171007_145440.jpg

IMG_20171007_145449.jpg

IMG_20171007_145453.jpg

IMG_20171007_145533.jpg

As you can see wires seem to be cut off, can't imagine it being like that from factory?

Cheers.
 

Faheem

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Also want to know what this wire is for

IMG_20171007_173349.jpg

IMG_20171007_173345.jpg


Came with the seats but I can't find where it goes unfortunately.
 

GazHyde

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Hmmm, that looks a bit of a mess. The loom adapter should sort that out but you may well have to find the wiring diagrams and splice them together.

The last picture could be the seat occupancy sensor connector? Usually seen attached to the seat...
 

Faheem

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@GazHyde thanks, all the wires are there but some had been cut at some point - and hidden in the seat - assuming that previous owner of the seats had done the same thing (fit the seats in a pre facelift car by swapping the connectors from an existing pre facelift seat into a facelift seat)... and to remove the connectors he would have had to cut a couple of wires.

All soldered back in, now just need to find where this clip sits!

IMG_20171007_205154.jpg
 

Sean d

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Don't connect the seat occupancy sensor mate as the airbag light will come on.
 

Faheem

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@Sean d Cheers mate, is this the connector for the seat occupancy sensor?

It's the only connector that I can't plug into anything so I'm thinking it must be...

IMG_20171007_225427.jpg
 

Dino D

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I believe it is only passenger side seat that has an occupancy sensor. If you have no passenger side airbag then there is nothing to plug it into anyway. I think early cars didn't have them at all.
 

Dino D

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@GazHyde thanks, all the wires are there but some had been cut at some point - and hidden in the seat - assuming that previous owner of the seats had done the same thing (fit the seats in a pre facelift car by swapping the connectors from an existing pre facelift seat into a facelift seat)... and to remove the connectors he would have had to cut a couple of wires.

All soldered back in, now just need to find where this clip sits!

View attachment 67035
That clip looks the one tha goes around the seatbelt pretensioner firing device thing to run the cable neatly to stop it getting run over in the runner. They usually don't held very well so a trust cable tie will help here.
It is a tube shape bolted to the side of the seat under the seatbelt clip.
 

Faheem

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Cheers @Dino D

Got everything in to the car and plugged it in but the heated seats wouldn't work, was missing the relay in the fuse box so used the horn relay (same P/N) to test.

Passenger side works brilliantly. Drivers side didn't work at all. So had to remove it from the car unplug everything and start dismantling the seats (which I hate doing because I can never get it back to the way it was) sure enough burnt out wire...

IMG_20171008_142636.jpg

Part of the foam had also collapsed so some duct tape
IMG_20171008_154906.jpg


Unfortunately I can't put the hog rings back on :( I spent the best part of 10 minutes trying to put it back on but it refuses to stay on. Is there any harm to not putting the rings back on?

Also I absolutely hate the little clips that you have to hook the fabric of the seats onto, can't find the existing hole so end up making new ones!!

And I thought this would be a simple Saturday morning job.... :whistle:
 

Sean d

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The hog rings are a must mate and are a piece of cake with long nose pliers, are you going to replace the heat pad.
 

Faheem

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What's the purpose of the hog rings? @Sean d the standard seats I had didn't have them, so I'm assuming they're responsible for the heating element?

I wasn't planning to replace the heat pads... I wouldn't know where to get a replacement from! I just cut the burnt wire out and replaced it with a new piece which I've soldered on.
 

Dino D

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I used strong cable ties in place of hog rings.
Easy to work with and does the same job.
I love a cable tie...
I'm going to write a book...5001 things to do with a cable tie..
 

Faheem

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I love cable ties. I'd much prefer a cable tie than a hog ring
 

Dickymint

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yep used cable ties as well, was able to pull the leather back into shape easier as well, I used upholstery glue to glue the foam where it had split before using the tape to reinforce it :)
 

Ianmc

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Hog rings are easy, if you have the special plyers.
 

Faheem

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Well went back to do the hog rings and found that the old wire - what was left of it had burnt in another place close to the original damaged section so was was in the process of replacing that today.

Out of interest has anyone replaced the heater pads and if so what did you use?

My main issue at the moment is that I can't get the seats to heat up by supplying power to the two wires coming out the heater pads, I would have thought that if I were to supply power to the two wires the seats would heat up and allow me to test that they work before reassembling the seats and fitting them to the car.
IMG_20171010_220632.jpg


I've tried a thin wire and a thick one as I thought after trying the thick wire perhaps the thickness will affect the amount of time it takes for the pads to warm up?

My knowledge of electronics unfortunately is worse than my knowledge of mechanics- so pretty damn poor!!

I'd like to go with a thick wire as there's less chance of it breaking even with it being buried in the sponge.

However I know little about wire gauges but know enough that mixing and matching could cause other problems! Can anyone advise? :thumbsup:

Blue and brown wires are the ones I've tested, used a multimeter to check and looks okay but just can't get hear.

That soldering job is temporary but wanted to know if they'd heat up before finalising things and putting the cover back on.

IMG_20171010_220730.jpg
 

mrscalex

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Are the hog rings reuseable after removal? Or do you need a new supply - if so what size, assuming they come in different sizes?

I'm getting myself some proper pliers. They are under £10 for some Sealeys.
 

Faheem

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I think they are reusable unless they've been bent one too many times in which case they break in the middle. I still prefer using zip ties as it seems a lot easier. What's the tool if you don't mind me asking?
 
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